Welcome to the 55th Ohio State University International Symposium

Welcome to the 55th Ohio State University International Symposium on Molecular Spectroscopy On behalf of the Executive Committee, Frank DeLucia, Eric Herbst, Weldon Mathews, Russell Pitzer, and myself, I wish to extend to all our Symposium guests a heartfelt welcome to Ohio State and Columbus. Once again this June spectroscopists from around the world have gathered at this Symposium to report their latest work and learn about recent advances by others. Whether it is one of our plenary lectures or the first talk of a student, each contains new information and is important. As the organizers of the Symposium, we are pleased to be able to facilitate this process. The essence of the meeting remains the scientific exchanges and the personal experiences of the conferees this week, independent of the number of times that you have attended this meeting. If we can help in any manner, please do not hesitate to ask. Terry A. Miller Symposium Chair

Contents SCHEDULE OF TALKS ABSTRACTS Monday (M)....................1 Monday (M).................72 Tuesday (T)...................15 Tuesday (T)................103 Wednesday (W).............34 Wednesday (W)..........152 Thursday (R).................48 Thursday (R)..............184 Friday (F)......................65 Friday (F)...................226 AUTHOR INDEX...............239

55th OHIO STATE UNIVERSITY INTERNATIONAL SYMPOSIUM ON MOLECULAR SPECTROSCOPY JUNE 12-16, 2000

International Advisory Committee Executive Committee Phil Bunker (NRCC) Chair* Terry A. Miller, Chair Takayoshi Amano (Ibaraki U.) Frank C. DeLucia, Eric Herbst Peter Botschwina (U. G¨ottingen) C. Weldon Mathews, Russell M. Pitzer Michael A. Duncan (U. Georgia)* Please send correspondence to: Michael C. L. Gerry (U. British Columbia)* Terry A. Miller William R. M. Graham (TCU) International Symposium on Edward Grant (Purdue U.) Molecular Spectroscopy Michel Herman (U. Libre de Bruxelles) Department of Chemistry Yen-Chu Hsu (Academia Sinica) 120 West 18th Avenue *steering committee member Columbus, Ohio 43210 USA e-mail: [email protected] http://molspect.mps.ohio-state.edu/symposium/

International Advisory Committee Robert Kuczkowski (U. Michigan) Jaan Laane (Texas A&M U.) John P. Maier (U. Basel) A. Robert McKellar (NRC)* Agnes Perrin (Universit´e Paris Sud) Eric Rohlfing (OBES, DOE)* David Dale Skatrud (ARO) Richard D. Suenram (NIST) Keiichi Tanaka (Kyushu U.) *steering committee member 614-292-2569 (phone),-1948 (FAX)

Special Sessions Several special mini-symposia are planned for this year’s meeting. Wolfgang Ernst, Penn State University, has organized a session entitled, “Vibronic Interactions” which covers the classical Jahn-Teller and Renner-Teller effects as well as other vibronic interactions. Invited speakers are Horst Koeppel, University of Heidelberg, Anthony Merer, University of British Columbia, and Timothy Barckholtz, JILA. A second mini-symposium was organized by Michael Duncan, University of Georgia, on the subject of “Metal Complexes” from diatomics to moderately large clusters. Invited speakers for this mini-symposium are Paul Dagdigian, Johns Hopkins University and Gert von Helden, University of Nijmegen. A third mini-symposium has been organized by John Maier, University of Basel on “Negative Ions.” The symposium will cover both experiments and theory involving negative ions. Invited speakers are Carl Lineberger, University of Colorado, and Jack Simons, University of Utah. A session on theory has been organized by Russell Pitzer, Ohio State University, featuring a talk by Michael Robb, King’s College London.

Picnic The Symposium picnic is on Wednesday evening, June 14, at the Fawcett Center. The cost of the picnic is included in your registration (at below cost to students), so that all may attend the event. The Coblentz Society is the host for refreshments at 6:30pm before the picnic at 7:30pm at the Fawcett Center.

Sponsorship We are pleased to announce that the Army Office of Research is continuing its long sponsorship of the Symposium. We are also receiving support from The Ohio State University through the Chemistry and Physics Departments and the College of Mathematical and Physical Sciences. Our Corporate sponsors are Coherent Inc., Parker Hannifin Corp.-The General Valve Operation and Spectra Physics. As in the past, Coherent will sponsor the coffee and doughnuts. The support of Parker Hannifin Corp.-The General Valve Operation subsidizes the cost of printing the abstract book. The support of Spectra Physics allows us to reduce the cost of the picnic for students. We are pleased to acknowledge Lambda Physik as a Contributing sponsor. Lambda Physik sponsors a reception honoring our invited speakers and session chairs. In addition to our Corporate and Contributing sponsors, ABB BOMEM, Bruker USA, Laser Analytics and Ontar will have exhibits at the Symposium. Academic Press supports a review lecture in one of the mini-symposia each year. Our sponsors will have exhibits at the Symposium and we encourage you to visit their displays as well as those of our other exhibitors.

Rao Prize The three Rao Prizes for the most outstanding student talks at the 1999 meeting will be presented. The winners are R. Timothy Bonn, University of Pennsylvania; Sachiko Itono, Ochanomizu University; and Sabine F. Deppe, Universit¨at G¨ottingen. The Rao Prize was created by a group of spectroscopists who, as graduate students, benefited from the emphasis on graduate student participation, which has been a unique characteristic of the Symposium. This coming June three more Rao Prizes will be awarded. The award is administered by a Prize Committee chaired by Arlan Mantz, Connecticut College, and comprised of Michael Heaven, Emory University; Angela R. Hight Walker, NIST; Kevin Lehmann, Princeton University; John Muenter, University of Rochester; and Deanne Snavely, Bowling Green State University. Any questions or suggestions about the Prize should be addressed to the Committee. Anyone (especially post-docs) willing to serve on a panel of judges should contact Arlan Mantz (e-mail: [email protected]).

Information ACCOMMODATIONS: The check-in for dormitory accommodations is located in Drackett Tower (F) on Curl Drive. Drackett Tower will open at 10:00a.m. Sunday, June 11, and remain open 24 hours a day through the Symposium. The dorm dining room will be open. Meal plans may be purchased upon registration. Inquire upon check-in. Other hotels close to campus include: Fawcett Center, 2400 Olentangy River Rd., 292-3238; Holiday Inn on the Lane, 328 W. Lane Ave., 294-4848; Red Roof Inn, State Route 315 & Ackerman Rd., 267-9941; University Plaza Hotel, 3110 Olentangy River Rd., 267-7461; Best Western University Inn, 3232 Olentangy River Rd., 261-7141. NOTE: When making reservations with the Holiday Inn on the Lane or the University Plaza Hotel, mention that you are with the Molecular Spectroscopy Symposium and you will be given the OSU discount, if available. MAIL: As in recent years, computer facilities for email will be available. Address your regular mail for delivery during the Symposium to: c/o MOLECULAR SPECTROSCOPY SYMPOSIUM, Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, Ohio, 43210, U.S.A. FAX number - (614) 292-1948, Telephone number - (614) 292-2569.

PARKING: Parking permits, for the week, are available only from the check-in desk at Drackett Tower. These permits allow you to park in any “C” parking space on campus. The permit must be displayed on the front windshield of your car. Please follow all traffic rules to avoid the issuance of tickets. REGISTRATION: The Registration Desk will be located in Room 1011B, Physics Laboratory. It will be kept open between 4:00-6:00 p.m. Sunday, and 8:15a.m. - 4:30p.m., Monday through Friday. Those who have prepaid their registration and who are staying in the dorms will receive their registration packet at dormitory check-in. If you have prepaid your registration but are not staying at the dorms, pick up your packet at the Registration Desk. NOTE: If the dates of your stay change after Friday, June 2, please settle your dorm account with Drackett Tower directly. LIABILITY: The Symposium fees DO NOT include provisions for the insurance of participants against personal injuries, sickness, theft or property damage. Participants and companions are advised to take whatever insurance they consider necessary. Neither the Symposium organizing committee, its sponsors, nor individual committee members assume any responsibility for loss, injury, sickness, or damages to persons or belongings, however caused. AUDIO/VIDEO INFORMATION: Overhead projectors will be available for each session. Since use of slide projectors has been essentially non-existent in recent years, they are no longer available routinely. Anyone needing a slide projector, or any other special audio/video equipment, should contact the Symposium office at least two weeks (May 29) before the meeting. ACKNOWLEDGEMENTS: The Symposium Chair wishes to acknowledge the hard work of numerous people who make this meeting possible. Key among these people are Becky Gregory, who solves everyone’s problems and keeps the meeting running smoothly; Susan Murnane-Hughes who keeps track of the dollars; and my student assistant, Keith Edwards, who ensures the lights go on and other essentials appear. We wish to acknowledge the hospitality of the Physics Department in tolerating our invasion each year. Sergey Panov wrote the majority of the script for the electronic aspects of the Symposium; Computer Support in Chemistry helps us keep it and other aspects of our services operational. Finally, all the students in my group play vital roles in helping make sure nothing falls through the cracks.

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MA. PLENARY MONDAY, JUNE 12, 2000 – 8:45 AM Room: AUDITORIUM INDEPENDENCE HALL Chair: WILLIAM SAAM, The Ohio State University, Columbus, OH Welcome C. Bradley Moore, Vice President for Research The Ohio State University

8:45

MA01 40 min 9:00 THE STRANGELY FAMILIAR WORLD OF UNFAMILIAR ION-PAIR RYDBERG STATES: EXOTIC ATOMS MADE FROM MOLECULES JOHN W. HEPBURN, Dep’t of Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1, CANADA. MA02 40 min 9:45 MOLECULAR PHYSICS STUDIES WITH FREE ELECTRON LASERS AND MOLECULAR DECELERATORS GERARD MEIJER, FOM Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3430 BE Nieuwegein, The Netherlands, http://www.rijnh.nl, and Department of Molecular and Laser Physics, University of Nijmegen, Toernooiveld 1, NL-6525 ED Nijmegen, The Netherlands.

Intermission TRIBUTE TO K. NARAHARI RAO and RAO AWARDS Presentation of Awards by Arlan Mantz, Connecticut College

10:45

1999 Rao Award Winners R. Timothy Bonn, University of Pennsylvania Sachiko Itono, Ochanomizu University Sabine F. Deppe, Universit¨at G¨ottingen COBLENTZ AWARD Presentation of Award by John Hellgeth, Coblentz Society Chair

MA03

Coblentz Society Award Lecture

40 min

11:20

VIBRATIONAL DYNAMICS FROM SMALL MOLECULES TO PROTEINS MARTIN GRUEBELE, Departments of Chemistry and Biophysics, and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Illinois 61801.

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ME. INFRARED MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1153 SMITH LAB Chair: JEAN VANDER AUWERA, Universit´e Libr´e de Bruxelles, Brussels, Belgium ME01 NEW EXPANSIONS OF POTENTIAL ENERGY FOR DIATOMIC MOLECULES

15 min

1:30

M. MOLSKI and J. KONARSKI, Theoretical Chemistry Department, A. Mickiewicz University, ul. Grunwaldzka 6, PL 60-780 Pozna´n, Poland.. ME02 A THEORETICAL INVESTIGATION OF THE SILICON-CARBON CHAIN MOLECULE SiC8

10 min

1:47

P. BOTSCHWINA, B. SCHULZ, R. OSWALD, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany; H. STOLL, Institut f¨ur Theoretische Chemie, Universita¨ t Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany. ME03 15 min 1:59 NC6 N AND NC5 NC: COUPLED CLUSTER CALCULATIONS AND IMPROVED ASSIGNMENTS OF IR AND RAMAN SPECTRA P. BOTSCHWINA, R. OSWALD, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany. ME04 15 min 2:16 AB INITIO CALCULATION OF CONFORMATIONS AND INFRARED SPECTRA OF MESO AND RACEMIC 2,4PENTANEDIOL D. L. REYNOLDS, N. MINA-CAMILDE, and C. E. MANZANARES, Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798; A. J. HERNANDEZ, and M. C. SALAZAR, Department of Chemistry, Simon Bolivar University, Caracas 1080A,Venezuela. ME05 15 min 2:33 PHASE SHIFT CAVITY RING DOWN MEASUREMENT OF VIBRATIONAL OVERTONE ABSORPTIONS E. K. LEWIS, X. Li, and C. E. MANZANARES, Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798; A. J. HERNANDEZ, and M. C. SALAZAR, Department of Chemistry, Simon Bolivar University, Caracas 1080A, Venezuela.

Intermission ME06 LEAD SALT SEMICONDUCTOR LASER EMISSION LINESHAPE ANALYSIS

15 min

3:10

B. AOAEH, Y. ABEBE, A. W. MANTZ, Department of Physics, Astronomy and Geophysics, Connecticut College, New London, CT 06320; C. D. BALL and F. C. DeLUCIA, Department of Physics, The Ohio State University, 174 W. 18th Ave., Columbus, Ohio 43210-1106; D. CHRIS BENNER, Department of Physics, College of William and Mary, Box 8795, Williamsburg, VA 23187; M. A. H. SMITH, Atmospheric Sciences Division, MS 401A, NASA Langley Research Center, Hampton, VA 23618-2199.

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ME07 15 min 3:27 MEASUREMENTS OF 1-0 BAND OF CARBON MONOXIDE AT TEMPERATURES BETWEEN 11 AND 296 KELVINS B. AOAEH, N. KOLODZIEJSKI, A. W. MANTZ, Department of Physics, Astronomy and Geophysics, Connecticut College, New London, CT 06320; D. CHRIS BENNER, V. MALATHY DEVI, Department of Physics, College of William and Mary, Box 8795, Williamsburg, VA 23187-8795; M. A. H. SMITH, Atmospheric Sciences Division, MS401A, NASA Langley Research Center, Hampton, VA 23618-2199; C. D. BALL and F. C. DeLUCIA, Department of Physics, The Ohio State University, 174 W. 18th Ave., Columbus, Ohio 43210-1106.

ME08 15 min 3:44 SUB-DOPPLER SPECTROSCOPY OF THE C–O STRETCHING FUNDAMENTAL BAND OF METHANOL BY USING MICROWAVE SIDEBANDS OF CO2 LASER LINES Z. D. SUN,F. MATSUSHIMA, S. TSUNEKAWA, AND K. TAKAGI, Department of Physics, Toyama University, Toyama 930-8555,Japan.

ME09 15 min 4:01 OBSERVATION OF DRESSED MOLECULES IN NEAR INFRARED-RF DOUBLE RESONANCE SPECTROSCOPY OF CH3 I CHIKAKO ISHIBASHI, RYUJI SANETO, and HIROYUKI SASADA, Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan.

ME10 15 min 4:18 VIBRATION-ROTATION FLUORESCENCE SPECTRA OF WATER IN THE GROUND ELECTRONIC STATE MARIA SAARINEN, DMITRI PERMOGOROV, Laboratory of Physical Chemistry, P.O. Box 55 (A. I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland; LAURI HALONEN, JILA, University of Colorado, Campus Box 440, Boulder, Colorado 80309.

ME11 NEW INFRARED EMISSION MEASUREMENTS ON HNC

10 min

4:35

ARTHUR MAKI, 15012 24th Ave. S.E., Mill Creek, WA 98012; GEORG MELLAU, Physikalisch-Chemisches Institut, Justus-Liebig-Universit¨at, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany.

ME12 PRECISE TRANSITION FREQUENCY MEASUREMENTS OF CH4 IN THE 1.66 m REGION

15 min

4:47

CHIKAKO ISHIBASHI, KOTARO SUZUMURA, and HIROYUKI SASADA, Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan; MOTONOBU KOUROGI, KAZUHIRO IMAI, and BAMBANG WIDIYATMOKO, Graduate School at Nagatsuta, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan; ATSUSHI ONAE, National Research Laboratory of Metrology, 1-1-4, Umezono, Tsukuba 305-8563, Japan.

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ME13 15 min 5:04 CHARACTERIZATION OF ADSORPTION EFFECTS ON METALLIC SURFACES OF POLAR MOLECULES IN THE GAS PHASE BY FT-IR SPECTROSCOPY E. H. DOWDYE, and C. HARIDASS, Laser Spectroscopy Laboratory, Department of Physics & Astronomy and Center for the Study of Terrestrial & Extraterrestrial Atmospheres, Howard University, Washington, DC 20059; P. MISRAa , NASA Goddard Space Flight Center, Laser & Electro-Optics Branch, Code 554, Greenbelt, MD 20771. a 1999-2000

NASA Administrator’s Faculty Fellow at Goddard Space Flight Center

ME14 DIMENSIONAL EFFECT ON IR ABSORBTION BAND CONTOUR OF BENZENE E. N. SHERMATOV, Samarkand State University, Univ. bulv 15, 703004 Samarkand, Uzbekistan.

15 min

5:21

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MF. JET AND BEAM MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1009 SMITH LAB Chair: TIMOTHY G. WRIGHT, University of Sussex, Brighton, United Kingdom MF01 15 min 1:30 HELIUM AND HYDROGEN INDUCED ROTATIONAL RELAXATION OF H2 CO OBSERVED AT TEMPERATURES OF THE INTERSTELLAR MEDIUM MARKUS MENGEL and FRANK C. DE LUCIA, Department of Physics, The Ohio State University, 174 West 18th Ave., Columbus OH 43210, USA. MF02 15 min 1:47 INFRARED SPECTROSCOPY OF THE HCN-(H2 /D2 )n CLUSTERS IN THE SUPERFLUID HELIUM DROPLETS MASAZUMI ISHIGURO, ROGER E. MILLER, Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599. MF03 15 min 2:04 HIGH RESOLUTION INFRARED SPECTROSCOPY OF THE HCN-(o-H2 ) AND HCN-(p-D2 ) CLUSTERS IN THE GAS PHASE MASAZUMI ISHIGURO, ROGER E. MILLER, Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599. MF04 MILLIMETER-WAVE SPECTROSCOPY OF THE HCN-H2 CLUSTER

10 min

2:21

M. ISHIGURO and T. TANAKA, Department of Chemistry, Faculty of Science, Kyushu University 33, Hakozaki, Higashiku, Fukuoka 812-8581, Japan; C. J. WHITHAM, K. HARADA and K. TANAKA, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan. MF05

10 min

2:33

DIRECT OBSERVATION OF THE 2 3 u STATE OF Rb2 IN A PULSED MOLECULAR BEAM: ROTATIONAL+ BRANCH INTENSITY ANOMALIES IN THE 2 3 u (1u ) X 1 + g (0g ) BANDS Y. LEE,Y. YOON, S. J. BAEK, D-L JOO, J-S RYU and B. KIM, Department of Chemistry, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea. MF06 10 min 2:45 POLARIZATION QUAMTUM BEAT SPECTROSCOPY OF NO2 : HYPERFINE LEVEL STRUCTURE IN THE YELLOW REGION(16000-19250 CM 1 ) JU XIN AND SCOTT A. REID, Department of Chemistry, Marquette University, Milwaukee, WI 53201-1881.

Intermission

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MF07 15 min 3:15 VRT-SPECTROSCOPY IN THE TRANSLATIONAL AND LIBRATIONAL BAND REGION OF LIQUID WATER: HYDROGEN BOND TUNNELING DYNAMICS IN WATER CLUSTERS F. N. KEUTSCH, R. S. FELLERS, P. B. PETERSEN, M. R. VIANT, M. G. BROWN, and R. J. SAYKALLY, Department of Chemistry, University of California Berkeley, Berkeley, CA 94720. MF08 15 min 3:32 THE DEPENDENCE OF INTERMOLECULAR INTERACTIONS UPON VALENCE COORDINATE EXCITATION: THE vHF =4 LEVELS OF ArHF CHENG-CHI CHUANG, and WILLIAM KLEMPERER, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138. MF09 15 min 3:49 AN AB INITIO STUDY ON THE EXPLICIT rXF DEPENDENCE OF THE INTERMOLECULAR POTENTIALS OF ArHF AND ArClF: WHEN DOES Ar-X REPULSION BEGIN TO SHOW? KELLY J. HIGGINS, and WILLIAM KLEMPERER, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138. MF10 15 min 4:06 A SUB-DOPPLER RESOLUTION DOUBLE RESONANCE MOLECULAR BEAM INFRARED SPECTROMETER OPERATING AT 2eV: INVESTIGATION OF HCN AND HCCH HEMANT SRIVASTAVA, ANDRE´ CONJUSTEAU, KEVIN K. LEHMANN, and GIACINTO SCOLES, Department Of Chemistry, Princeton University, Princeton NJ 08544; HIDEO MABUCHI, Department Of Physics, California Institute Of Technology, Pasadena, CA 91125; ANDREA CALLEGARI, Laboratoire ´ De Chimie Physique Mol´eculaire (LCPM), Ecole Polytechnique F´ed´erale De Lausanne, CH-1015 Lausanne, Switzerland. MF11 15 min 4:23 MILLIMETER WAVE SPECTROSCOPY OF THE VAN DER WAALS BENDING BAND OF He-HCN WITH A MULTIREFLECTION JET CELL KENSUKE HARADA, CHRISTOPHER JAMES WHITHAM, AND KEIICHI TANAKA, Institute for Molecular Science, Okazaki, 444-8585, Japan. MF12 INFRARED SPECTRUM OF THE CO-NH3 COMPLEX

15 min

4:40

CHANGHONG XIA and A.R.W. McKELLAR, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada. MF13 15 min 4:57 IR SPECTRUM OF THE CO-N2 COMPLEX: ASSIGNMENTS FOR CO-paraN2 AND OBSERVATION OF A BENDING STATE FOR CO-orthoN2 CHANGHONG XIA, A.R.W. McKELLAR, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada; YUNJIE XU, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada.

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MF14 15 min 5:14 JET SPECTROSCOPY OF THE H-F OUT-OF-PLANE LIBRATIONAL FUNDAMENTAL BAND OF HYDROGEN FLUORIDE PENTAMER IN THE 741 cm 1 REGION THOMAS A. BLAKE, Pacific Northwest National Laboratory, P. O. Box 999, Mail Stop K8-88, 3020 Q Avenue, Richland, WA 99352 (PNNL is operated for the US Department of Energy by the Battelle Memorial Institute under contract DE-AC06-76RLO 1830).

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MG. NEGATIVE IONS MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1000 McPHERSON LAB Chair: JOHN MAIER, University of Basel, Basel, Switzerland MG01

Journal of Molecular Spectroscopy Special Review Lecture

30 min

1:30

SPECTROSCOPY AND DYNAMICS OF CLUSTER ANIONS W. CARL LINEBERGER, JILA and Department of Chemistry, University of Colorado, Boulder, CO 80309. MG02

15 min

2:05

FEMTOSECOND STIMULATED EMISSION PUMPING OF BARE AND CLUSTERED I2 ALISON V. DAVIS, MARTIN T. ZANNI, CHRISTIAN FRISCHKORN, Department of Chemistry, University of California, Berkeley, CA 94720; MOHAMMED ELHANINE, Laboratoire de Photophysique Mol´eculaire du CNRS, Bˆatiment 210, Universit´e Paris Sud, 91405 Orsay, France; and DANIEL M. NEUMARK, Department of Chemistry, University of California, Berkeley, CA 94720. MG03 STRUCTURE OF Sin CLUSTER ANIONS: COMPARISON OF THEORY AND EXPERIMENT

15 min

2:22

¨ Universit¨at Konstanz, 78457 Konstanz, Germany; B. LIU and K. HO, ¨ J. MULLER and G. GANTEFOR, Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames Iowa 50011; A.A. SHVARTSBURG and K.W.M. SIU, Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J1P3; S. OGUT and J.R. CHELIKOWSKY, Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455. MG04 SPECTROSCOPIC STUDY OF THE STEPWISE SOLVATION OF CN


(H2 O)n VIA IR-VPS

10 min

2:39

C. K. WONG, J. D. LOBO, M. OKUMURA, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125. MG05 NEGATIVE ION PHOTOELECTRON SPECTROSCOPY OF SOLVENT-STABILIZED ANIONS

15 min

2:51

SHOUJUN XU, JOHN MICHAEL NILLES, WEIJUN ZHENG and KIT H. BOWEN, Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218. MG06 15 min A PHOTOELECTRON STUDY OF ANION-AROMATIC INTERACTIONS: A PROGRESS REPORT

3:08

JOHN MICHAEL NILLES, SHOUJUN XU, OWEN THOMAS, WEIJUN ZHENG and KIT H. BOWEN, Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218.

Intermission

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MG07 AUTODETACHMENT LIFETIMES OF SMALL DIANIONS

15 min

3:40

THOMAS SOMMERFELD, Theoretische Chemie, Universita¨ t Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany; FRANCESCO TARANTELLI, Dipartimento di Chimica, Universita` di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy. MG08

15 min

3:57

THE HF2 -H2 O COMPLEX: A THEORETICAL STUDY I.P. HAMILTON, BRANDON REINHART and G.P. LI, Department of Chemistry, Wilfrid Laurier University, Waterloo, Canada N2L 3C5. MG09 15 min 4:14 USING PHOTOELECTRON AND ABSORPTION SPECTRA OF HYDRATED ELECTRON CLUSTERS TOGETHER TO BETTER UNDERSTAND THE ELECTRONIC PROPERTIES OF BULK WATER JAMES V. COE, Department of Chemistry, The Ohio State University, Columbus, OH 43210-1173. MG10 15 min 4:31 THE CHANGE OF THE ELECTRONIC STRUCTURE OF METAL CLUSTERS UPON HYDROGEN CHEMISORPTION ¨ Fakult¨at f¨ur Physik, University ¨ S. BURKART, N. BLESSING, B. KLIPP, J. MULLER and G. GANTEFOR, of Konstanz, D-78457 Konstanz, Germany. MG11 15 min 4:48 THEORETICAL STUDY OF THE SPECTROSCOPY AND DYNAMICS OF THE VINYLIDENE-ACETYLENE ISOMERIZATION ¨ RAINER SCHORK, Theoretical Chemistry, University of Heidelberg, INF 229, D-69120 HORST KOPPEL, Heidelberg, Germany.

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MH. MICROWAVE MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1015 McPHERSON LAB Chair: WOLFGANG JAEGER, University of Alberta, Edmonton, Canada

MH01 15 min 1:30 FOURIER TRANSFORM MICROWAVE DETECTION OF FREE RADICALS RELEVANT TO COMBUSTIONAND ATMOSPHERIC CHEMISTRY ¨ N. HANSEN, H. MADER, and F. TEMPS, Institut f¨ur Physikalische Chemie, Christian-Albrechts-Universita¨ t Kiel, Olshausenstr. 40, D-24098 Kiel, Germany.

MH02 15 min 1:47 NEW RESULTS FROM THE ROTATIONAL SPECTRA OF THE HALOGEN MONOXIDES. INTERATOMIC POTENTIALS, FINE AND HYPERFINE INTERACTIONS. B. J. DROUIN, E. A. COHEN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099; C. E. MILLER, Department of Chemistry, Haverford College, Haverford, PA 19041-1392; and ¨ H. S. P. MULLER, I. Physikalisches Institut, Universit¨at zu K¨oln, Z¨ulpicher Str. 77, D-50937, K¨oln, Germany.

MH03

15 min

2:04

THE ROTATIONAL SPECTRA OF THE X1 2 1=2 and X2 2 3=2 STATES OF BiO EDWARD A. COHEN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109-8099; DAMIAN M. GOODRIDGE and KENTAROU KAWAGUCHIa , Nobeyama Radio Observatory, Minamimaki, Minamisaku, Nagano 384-1305, Japan. a Present

address: Okayama University, Faculty of Science, Tsushimanaka 3-1-1, Okayama, 700-8530, Japan.

MH04 15 min 2:21 ELECTRIC DISCHARGE VS. EXCIMER LASER PHOTOLYSIS: A COMPARISON OF TWO METHODS USED TO PREPARE UNSTABLE MOLECULES FOR FOURIER TRANSFORM MICROWAVE SPECTROSCOPIC STUDY ´ ERIC ´ BETHANY BRUPBACHER-GATEHOUSE and FRED MERKT, Laboratorium f¨ur Physikalische Chemie, Eidgen¨ossische Technische Hochschule, ETH-Zentrum, CH-8092 Zu¨ rich, Switzerland.

MH05 MILLIMETER WAVE SPECTRA OF CHLORINE NITRATE

15 min

2:38

REBECCA A.H. BUTLER, Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, OH 43210; PAUL HELMINGER, Department of Physics and Chemistry, University of South Alabama, Mobile, AL 36688; FRANK C. DE LUCIA, Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, OH 43210.

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MH06 MILLIMETER WAVE, INFRARED AND AB INITIO STUDY OF FPS

15 min

2:55

¨ HELMUT BECKERS, HANS BURGER, PETER PAPLEWSKI, Anorganische Chemie, FB 9, Universit¨at¨ GH, D-42097, Wuppertal, Germany; JURGEN BREIDUNG, WALTER THIEL, Max-Planck-Institut f¨ur Kohlenforschung, D-45470 M¨ulheim an der Ruhr, Germany; MARCEL BOGEY, PASCAL DREAN and ADAM D. WALTERS, Physique des Lasers, Atomes et Mol´ecules, Centre d’Etudes et de Recherches Lasers et Applications, Universit´e des Sciences et Technologies de Lille, F-59655 Villeneuve d’Ascq, France.

Intermission MH07 15 min 3:30 FEMTO-SECOND DEMODULATION AS A HIGH SPECTRAL PURITY SOURCE FOR THZ SPECTROSCOPY J. R. DEMERS, Department of Physics, The Ohio State University, 174 W. 18th Ave, Columbus, Ohio 432101106; T. M. GOYETTE, University of Massachusetts, Submillimeter Technology Lab, 175 Cabot Street, Lowell, Massachusetts, 01854; B. D. GUENTHER, Physics Department, Duke University, Durham, North Carolina, 27708-0305; F. C. DE LUCIA, Department of Physics, The Ohio State University, 174 W. 18th Ave, Columbus, Ohio 43210-1106.

MH08 15 min 3:47 QUASI-MICROWAVE SPECTROSCOPY OF NON-POLAR DIATOMIC MOLECULE BY USING OPTICAL PHASELOCKED LASERS. MOTOHIRO KUMAGAI, HIDETO KANAMORI, Tokyo Institute of Technology, Department of Applied Physics, Ohokayama, Meguro-ku, Tokyo, Japan; MICHIO MATSUSHITA, TATSUHISA KATO, Institute for Molecular Science, Okazaki, Japan.

MH09 THE RADIO SPECTRA OF SICCH, SICN AND SiNC

15 min

4:04

A. J. APPONI, M. C. MCCARTHY, C. A. GOTTLIEB, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138..

MH10 LABORATORY DETECTION OF HC6 N

15 min

4:21

V. D. GORDON, M. C. McCARTHY, A. J. APPONI, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 and Division of Engineering & Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138.

MH11 10 min MILLIMETER-WAVE SPECTROSCOPY AND COUPLED CLUSTER CALCULATIONS FOR NCCP

4:38

L. BIZZOCCHI, C. D. ESPOSTI, Dipartimento di Chimica “D. Ciamician”, Universit`a di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy; P. BOTSCHWINA and B. SCHULZ, Institut f¨ur Physikalische Chemie, Universit¨at G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany.

12

MH12 LABORATORY DETECTION OF TWELVE CARBON-SULFUR CHAINS

15 min

4:50

V. D. GORDON, M. C. McCARTHY, A. J. APPONI, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 and Division of Engineering & Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138. MH13 Post-deadline Abstract 10 min 5:07 THE CHARACTERIZATION OF HYPERFINE EFFECTS IN YTTERBIUM HALIDE DIATOMIC MOLECULES USING MWFT SPECTROSCOPY CAMERON S. DICKINSON, Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, CANADA; NICHOLAS R. WALKER, Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, CANADA; JOHN A. COXON, Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, CANADA; MICHAEL C. L. GERRY, Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, CANADA.

13

MI. ELECTRONIC (LARGE) MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1005 SMITH LAB Chair: MARTIN GRUEBELE, University of Illinois, Urbana, IL MI01 15 min DETERMINATION OF EXCITED STATE DIPOLE MOMENTS OF GAS PHASE MOLECULES. PART I a

1:30

TIMOTHY M. KORTER, CHRISTOPHER J. BUTLER, DAVID R. BORST, and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260. a Work

supported by NSF.

MI02 15 min DETERMINATION OF EXCITED STATE DIPOLE MOMENTS OF GAS PHASE MOLECULES. PART II a

1:47

TIMOTHY M. KORTER and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260. a Work

supported by NSF.

MI03 15 min 2:04 DIRECT DETERMINATION OF MOLECULAR CONSTANTS FROM ROVIBRONIC SPECTRA WITH GENETIC ALGORITHMS W. LEO MEERTS, Department of Molecular and Laser Physics, University of Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands; J. A. HAGEMAN, R. WEHRENS, L. M. C. BUYDENS, Laboratory of Analytical Chemistry, University of Nijmegen; and R. DE GELDER, Department of Inorganic Chemistry, University of Nijmegen. MI04 15 min 2:21 A NEW LOOK AT A CHIRAL PROTOTYPE: ROTATIONALLY RESOLVED MW AND UV SPECTRA OF JETCOOLED 1,1’-BI-2-HYDROXYNAPHTHALENE S. DAVIS, D. F. PLUSQUELLIC and R. D. SUENRAM, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899. MI05 15 min 2:38 OPTICAL-OPTICAL DOUBLE RESONANCE AND CAVITY RING-DOWN STUDIES ON THIOPHOSGENE DAVID C. MOULE, Department of Chemistry, Brock University, St Catharines, ON, L2S3A1; EDWARD C. LIM and HAISHENG LIU, Department of Chemistry, Knight Chemical Laboratory, University of Akron, Akron, OH, 44325-3601; and RICHARD H. JUDGE, Department of Chemistry, University of Wisconsin-Parkside, Kenosha, WI 53141-2000. MI06 15 min 2:55 FRANCK–CONDON SPECTRAL CALCULATION ON TRANS–HYDROQUIONE USING CORRELATION FUNCTION APPROACH SANJAY WATEGAONKAR, G. NARESH PATWARI, Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India 400 004.; M. DURGA PRASAD, School of Chemistry, University of Hyderabad, Hyderabad, India 500 046..

14

Intermission MI07 SPECTROSCOPIC INVESTIGATION AND HYDROXYCOUMARIN DYE IN SOLGEL

PREDICTION

OF

LASER

ACTION

15 min 3:30 PROPERTIES OF 4-

ASMA SOHAIL FAROOQUI and Z. H. ZAIDI, Department of Physics, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025 India. MI08 HIGH RESOLUTION STUDY OF THE CONFORMERS OF 3-AMINOPHENOL. a

15 min

3:47

JENNIFER A. BARTELS, BRIAN BLASIOLE, TIMOTHY M. KORTER, and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. a Work

supported by NSF.

MI09 15 min 4:04 ROTATIONALLY RESOLVED FLUORESCENCE EXCITATION SPECTROSCOPY OF BENZYL ALCOHOL .a ALEXEI NIKOLAEV and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. a Work

supported by NSF

MI10 15 min 4:21 THE EFFECT OF KINEMATIC FACTORS ON ROTATIONALLY AND ROVIBRATIONALLY INELASTIC SCATTERING OF GLYOXAL MARIANA D. DUCA, CHARLES S. PARMENTER, Indiana University Department of Chemistry, Bloomington, Indiana 47405; SAMUEL M. CLEGG, Department of Geophysical Sciences, The University of Chicago, Chicago, Illinois 60637. MI11 15 min 4:38 ABSOLUTE CROSS SECTIONS FOR VIBRATIONAL ENERGY TRANSFER IN THE QUASI-CONTINUUM OF PARA-DIFLUOROBENZENE. UROS S. TASIC, TODD A. STONE, and CHARLES S. PARMENTER, Indiana University Department of Chemistry, Bloomington, Indiana 47405. MI12 STUDYING THE DYNAMICS OF THE RING-OPENING REACTION OF 1; 3

15 min CYCLOHEXADIENE

4:55

RAY DUDEK, CONOR EVANS, PETER WEBER, Department of Chemistry, Brown University, Providence, RI 02906. MI13 Post-deadline Abstract 15 min 5:12 TEMPERATURE DEPENDENCE OF THE RADIATIVE LIFETIME OF J-AGGREGATES WITH DAVYDOV SPLITTING OF THE EXCITATION BAND I. G. SCHEBLYKIN, M. M. BATAIEV and A. G. VITUKHNOVSKY, Lebedev Physical Institute, RAS, Leninsky pr.,53, 117924 Moscow, Russian Federation; M. VAN DER AUWERAER, Laboratory for molecular Dynamics and Spectroscopy, K.U.Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.

15

TA. ELECTRONIC (SMALL) TUESDAY, JUNE 13, 2000 – 8:30 AM Room: 1153 SMITH LAB Chair: CHRIS BALL, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA TA01 15 min 8:30 TERM ENERGIES, LINE POSITIONS, AND SPECTROSCOPIC CONSTANTS FOR THE OH MEINEL BAND SYSTEM P. C. COSBY, T. G. SLANGER, D. L. HUESTIS, Molecular Physics Laboratory, SRI International, Menlo Park, CA 94025; D. E. OSTERBROCK, University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064. TA02 LINEAR RYDBERG STATES OF WATER

15 min

8:47

10 min

9:04

W. L. GLAB and T. THOMPSON, Texas Tech University, Lubbock, TX, 79409. TA03 DISPERSED FLUORESCENCE SPECTRA OF SIMPLE CARBENES

BOR-CHEN CHANG, Department of Chemistry, National Central University, Chung-Li 32054, Taiwan; ANDREW J. BEZANT and TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210. TA04 15 min NEAR-INFRARED LASER SPECTROSCOPY OF BROMOMETHYLENE IN A SLIT JET EXPANSION

9:16

BOR-CHEN CHANG, Department of Chemistry, National Central University, Chung-Li 32054, Taiwan; MATHEW COSTEN, ANDREW J. MARR, GRANT RITCHIE, GREGORY E. HALL and TREVOR J. SEARS, Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000. TA05 15 min VIBRATIONALLY EXCITED BROMOMETHYLENE-MAPPING THE BENDING POTENTIAL SURFACE

9:33

TREVOR J. SEARS, ANDREW J. MARR, Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000; NILS HANSEN, Physical Chemistry Department, Christian-AlbrechtsUniversitaet Kiel, Olshausenstrasse 40-60, 24106 Kiel. TA06 BROMINE-CONTAINING RADICALS FORMED ON PHOTOLYSIS OF CHBr3

15 min

9:50

NILS HANSEN, Physical Chemistry Department, Christian-Albrechts-Universitaet Kiel, Olshausenstrasse 40-60, 24106 Kiel; ANDREW J. MARR and TREVOR J. SEARS, Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000.

Intermission

16

TA07 SINGLET TRANSITIONS OF METHYLENE AT 890 nm

15 min

10:20

KAORI KOBAYASHI, Department of Chemistry, Brookhaven National Laboratory, Upton, New York 119735000; LEAH D. PRIDE, ERULF Student at the Department of Chemistry, Brookhaven National Laboratory. Present address: Department of Chemical Technology, New York City Technical College, Brooklyn, NY 11201; and TREVOR J. SEARS , Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000. TA08

15 min

10:37

˜ 3 i STATE VIBRONIC STRUCTURE OF THE CCS RADICAL IN THE A MASAKAZU NAKAJIMA, YOSHIHIRO SUMIYOSHI and YASUKI ENDO, Depertment of Pure and Applied Sciences, College of Art and Sciences, The University of Tokyo, 153-8902, Tokyo, Japan. TA09 SEP SPECTROSCOPY OF THE HCCS RADICAL

15 min

10:54

TOMOKO ISHIBASHI, YOSHIHIRO SUMIYOSHI and YASUKI ENDO, Department of Basic Sciences, Graduate School of Arts and Sciences, University of Tokyo. TA10 10 min 11:11 SPECTROSCOPIC DETECTION AND CHARACTERIZATION OF THE SELENOKETENYL (HCCSe) RADICAL DAVID A. HOSTUTLER, AND DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055. TA11 15 min 11:23 JET AND LASER OPTOGALVANIC STUDIES OF THE ELECTRONIC SPECTRA OF GeH2 AND GeD2 AND AN IMPROVED STRUCTURE FOR GERMYLENE TONY C. SMITH, DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; WEI SHA and ALLAN G. ADAM, Department of Chemistry, University of New Brunswick, Fredericton, NB, Canada E3B 6E2. TA12 15 min 11:40 INVESTIGATION OF OPTOGALVANIC WAVEFORMS OF NEON AND ARGON UV TRANSITIONS FOR IDENTIFICATION OF THE PRIMARY ELECTRON COLLISIONAL IONIZATION PROCESS IN A HOLLOW CATHODE DISCHARGE H. E. MAJOR, and C. HARIDASS, Laser Spectroscopy Laboratory, Department of Physics and Astronomy and Center for the Study of Terrestrial and Extraterrestrial Atmospheres, Howard University, Washington, DC 20059; P. MISRAa , NASA Goddard Space Flight Center, Laser & Electro-Optics Branch, Code 554, Greenbelt, MD 20771. a 1999-2000

NASA Administrator’s Faculty Fellow at Goddard Space Flight Center

17

TB. CONDENSED PHASE TUESDAY, JUNE 13, 2000 – 8:30 AM Room: 1009 SMITH LAB Chair: MARILYN JACOX, NIST, Gaithersburg, MD TB01

15 min 8:30 4 MOLECULAR ROTATION IN SUPERFLUID He NANODROPLETS: THE VALIDITY OF A HYDRODYNAMIC MODEL CARLO CALLEGARI, ANDRE´ CONJUSTEAU, IRENE REINHARD, KEVIN K. LEHMANN, and GIACINTO SCOLES, Department of Chemistry, Princeton University, Princeton NJ 08544; FRANCO DALFOVO, Dipartimento di Matematica e Fisica, Universit`a Cattolica del Sacro Cuore, I-25121 Brescia (Italy). TB02

15 min

8:47

MICROWAVE SPECTROSCOPY OF ISOTOPICALLY SUBSTITUTED MOLECULES IN 4 He NANODROPLETS: A TEST OF THE ADIABATIC FOLLOWING APPROXIMATION ANDRE´ CONJUSTEAU, CARLO CALLEGARI, IRENE REINHARD, KEVIN K. LEHMANN, and GIACINTO SCOLES, Department Of Chemistry, Princeton University, Princeton NJ 08544. TB03 15 min SPECTROSCOPY OF RUBIDIUM ATOMS AND MOLECULES ON COLD HELIUM NANODROPLETS

9:04

WOLFGANG E. ERNST, FRANK RUEDIGER BRUEHL AND RADU ALEX MIRON, Departments of Physics and Chemistry, Penn State University, 104 Davey Laboratory, University Park, PA 16802. TB04 SPECTROSCOPY OF Mg ATOM-DOPED HELIUM NANODROPLETS

15 min

9:21

J. REHO, U. MERKER, MATTHEW R. RADCLIFF, K. K. LEHMANN, and G. SCOLES, Dept. of Chemistry, Princeton University, Princeton, NJ 08544. TB05 SPECTROSCOPY OF Al ATOMS SOLVATED IN HELIUM NANODROPLETS

10 min

9:38

J. REHO, U. MERKER, MATTHEW R. RADCLIFF, K. K. LEHMANN, and G. SCOLES, Dept. of Chemistry, Princeton University, Princeton, NJ 08544. TB06 X-RAY SPECTROSCOPY OF THE LIQUID WATER SURFACE

15 min

9:50

K. R. WILSON, B. S. RUDE, T. CATALANO, R. D. SCHALLER, J. G. TOBIN, and R. J. SAYKALLY, Department of Chemistry, University of California Berkeley, Berkeley, CA 94720.

Intermission

18

TB07 15 min 10:30 HIGH RESOLUTION INFRARED ABSORPTION SPECTROSCOPY OF THE FIRST OVERTONE PURE VIBRATIONAL TRANSITION Q2 (0) OF SOLID PARAHYDROGEN HIROYUKI KATSUKI and TAKAMASA MOMOSE, Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, JAPAN. TB08 15 min 10:47 STUDY OF STRUCTURAL FLUCTUATIONS IN AQUEOUS SOLUTIONS OF ACETIC ACID BY LIGHT SCATTERING METHODS B.S. OSMANOV, Department of Physics, The Ohio State University, Columbus OH 43210; F.H. TUKHVATULLIN, A. JUMABOEV, U. N. TASHKENBAEV, Samarkand State University, 703004 Samarkand, Uzbekistan. TB09 10 min 11:04 DIFFERENT POLARIZED COMPONENTS SHAPE OF RAMAN 1343 CM-1 BAND FOR NITRO-BENZENE AND ITS SOLUTIONS F. H. TUKHVATULLIN, A. JUMABOEV, U.N. TASHKENBAEV, S.A. OSMANOV, Z. MAMATOV, H. A. HUSHVAKTOV, Samarkand State University, 703004 Samarkand, Uzbekistan. TB10 15 min 11:16 INFRARED SPECTRA OF ACETONITRILE AND RELATED COMPOUNDS ADSORBED ON ALKALI HALIDE FILMS DENISE MAHALIDGE, N. SATISH CHANDRA, CANDICE TAYLOR, AND C. A. BAUMANN, Department of Chemistry, University of Scranton, Scranton, PA 18510-4626. TB11 15 min 11:33 THE PHOTOLUMINESCENCE FROM HYDROGEN-RELATED SPECIES IN COMPOSITES OF SiO2 NANOPARTICLES YURI D. GLINKA, SHENG-HSIEN LIN AND YIT-TSONG CHEN, Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, and Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan. TB12 10 min 11:50 ISOMERIC STRUCTURAL STUDY OF DIAMINES IN LIQUID STATE AND ITS INTERACTIONS WITH ALCOHOLS THROUGH DIELECTRIC SPECTROSCOPIC METHOD N.M.MORE,, Department of Physics, Dr B.A..M University, Aurangabad, PIN-431004, Mharashtra (India); S.C.MEHROTRA, Department of Electronics and Computer Science, Dr.B.A.M. Univesity, Aurangabad, PIN431004, Maharashtra (India).

19

TC. NEGATIVE IONS TUESDAY, JUNE 13, 2000 – 8:30 AM Room: 1000 McPHERSON LAB Chair: W. CARL LINEBERGER, University of Colorado, Boulder, CO TC01 Invited Talk 30 min 8:30 UNUSUAL NEGATIVE MOLECULAR IONS AND DIANIONS AND CHEMICAL BONDS INVOLVING RYDBERG ORBITALS JACK SIMONS, Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, Utah 84112. TC02 15 min 9:05 CARBON CHAIN ANIONS OF ASTROPHYSICAL INTEREST: PHOTODETACHMENT SPECTROSCOPY AND THEORETICAL CALCULATIONS ¨ NICHOLAS M. LAKIN, M. TULEJ, M. PACHKOV, F. GUTHE AND J.P. MAIER, Institut f¨ur Physikalische Chemie, Universit¨at Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.. TC03

15 min

9:22

GROUND STATE POTENTIAL ENERGY SURFACE AND ROVIBRATIONAL STRUCTURE OF C3 H NICHOLAS M. LAKIN, Institut f¨ur Physikalische Chemie, Universita¨ t Basel, Klingelbergstrasse 80, CH4056 Basel, Switzerland; M. HOCHLAF AND P. ROSMUS, Theoretical Chemistry Group, Universit´e de Marne-La-Vale´e, F-77454 Champs sur Marne, France. TC04 15 min AN EFFICIENT MECHANISM LEADING TO THE FORMATION OF NEGATIVE IONS IN SPACE

9:39

RADOSLAVA V. TERZIEVA and ERIC HERBST, Departments of Physics and Astronomy, and Chemical Physics Program, The Ohio State University, Columbus, OH 43210. TC05

15 min

9:56

TIME RESOLVED DYNAMICS OF ELECTRONIC EXCITATIONS IN C3 ¨ H.J. MUNZER, ¨ ¨ S. MINEMOTO, J. MULLER, R. FROMHERZ, G. GANTEFOR, J. BONEBERG, and P. LEIDERER, Universit¨at Konstanz, 78457 Konstanz, Germany. TC06

10 min

10:13

COUPLED CLUSTER CALCULATIONS FOR C4 H , AN ANION OF INTEREST TO ASTROCHEMISTRY P. BOTSCHWINA, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany.

Intermission

20

TC07

10 min

OBSERVATION OF METASTABLE AUTODETACHING STATES OF METHIDE, CH3

10:40

a

STEPHEN E. MITCHELL and JOHN W. FARLEY, Department of Physics, University of Nevada, Las Vegas, NV 89154. a Supported

by DOE/EPSCoR

TC08 THRESHOLD ION-PAIR PRODUCTION SPECTROSCOPY (TIPPS) of H2 S

15 min

10:52

Q. J. HU, X. K. HU, R. C. SHIELL, and J. W. HEPBURN, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. TC09 15 min VIBRATIONAL SPECTROSCOPY OF NEGATIVE IONS BY STIMULATED RAMAN PUMPING

11:09

MICHAEL R. FURLANETTO, NICHOLAS L. PIVONKA, and DANIEL M. NEUMARK, Department of Chemistry, University of California, Berkeley, CA 94720. TC10 10 min 11:26 TWO-ELECTRON WAVEFUNCTIONS FOR THE GROUND AND EXCITED STATES OF ALKALI NEGATIVE IONS S. MAGNIER, Laboratoire de Physique Mol´eculaire et des Collisions, Technopoˆ le 2000, 1 Bd Arago, F-57078 Metz Cedex 3. TC11 15 min 11:38 RESONANCES IN SN 2 REACTIONS: TWO-DIMENSIONAL QUANTUM CALCULATIONS ON A NEW POTENTIAL ENERGY SURFACE FOR CL + CH3 CL J. HAUSCHILDT, R. SCHINKE, Max-Planck-Institut f¨ur Str¨omungsforschung, Bunsenstr. 10, D-37073 G¨ottingen, Germany; P. BOTSCHWINA and S. SCHMATZ, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstr. 6, D-37077 G¨ottingen, Germany.

21

TD. JET AND BEAM TUESDAY, JUNE 13, 2000 – 8:30 AM Room: 1015 McPHERSON Chair: JOHN MUENTER, University of Rochester, Rochester, NY TD01 ROTATIONAL SPECTRUM OF DIMETHYL METHYLPHOSPHONATE

15 min

8:30

R. D. SUENRAM, F. J. LOVAS, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD., 208998441; A. LESARRI, Departamento de Qu´ımica F´ısica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid, Spain; J. O. JENSEN, and A. C. SAMUELS, Passive Standoff Detection Group, Edgewood Chemical and Biological Center, Edgewood Area, Aberdeen, MD 210105424. TD02 GROUP THEORY OF DIMETHYL METHYL PHOSPHONATE

15 min

8:47

JON T. HOUGEN, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441; NOBUKIMI OHASHI, Department of Physics, Faculty of Science, Kanazawa University Kakuma, Kanazawa 920-1192, Japan. TD03 VIBRATIONAL SPECTROSCOPY AND A POTENTIAL SURFACE FOR THIOPHOSGENE

15 min

9:04

BRENT STRICKLER and MARTIN GRUEBELE, Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801. TD04 15 min 9:21 TOLUENE INTERNAL ROTATION: REFINED BARRIER HEIGHT IN S1 , SIGN OF V6 , AND MOTION ALONG THE TORSIONAL COORDINATE.a DAVID R. BORST and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. a Work

supported by NSF

TD05 15 min 9:38 DESIGN AND PREFORMANCE CHARACTERISTICS OF A CONTINUOUS SLIT EXPANSION-FTIR SPECTROMETER SYSTEM ROBERT L. SAMS, ROBIN S. MCDOWELL , THOMAS A. BLAKE and STEVEN W. SHARPE, Pacific Northwest National Laboratory, P. O. Box 999, Mail Stop K8-88, Richland, WA 99352 (PNNL is operated for the US Department of Energy by the Battelle Memorial Institute under contract DE-AC06-76RLO 1830). TD06 A SLIT-JET INFRARED SPECTRUM OF 1,3-BUTADIENE

15 min

9:55

MARJO HALONEN, DAVID NESBITT, AND MICHAL FARNIK, JILA, University of Colorado, Campus Box 440, Boulder, Colorado 80309.

22

Intermission TD07 HIGH RESOLUTION INFRARED SPECTRA OF 2-METHYL-1-BUTEN-3-YNE

10 min

10:30

JOHN KESKE and B. H. PATE, Department of Chemistry, University of Virginia, McCormick Rd.,P.O. BOX 400319 Charlottesville, VA 22904. TD08 15 min 10:42 FEMTOSECOND PUMP/PROBE STUDY OF VIBRATIONAL LIFETIMES OF THE FUNDAMENTAL ACETYLENIC C-H STRETCH IN DILUTE SOLUTIONS HYUN S. YOO and BROOKS H. PATE, Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904. TD09 15 min 10:59 MODE-SPECIFICITY AND NON-RRKM KINETICS IN THE CONFORMATIONAL ISOMERIZATION OF 4CHLOROBUT-1-YNE JOHN KESKE and B. H. PATE, Department of Chemistry, University of Virginia, McCormick Rd., P.O. BOX 400319 Charlottesville, VA 22904. TD10 15 min 11:16 ROTATIONAL ANALYSIS OF CYCLOHEXYL METHYLPHOSPHONOFLUORIDATE (CYCLOHEXYL SARIN (GF)) R. D. SUENRAM, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 208998441; J. O. JENSEN, A. C. SAMUELS, M. W. ELLZY, and J. M. LOCHNER, Passive Standoff Detection, Edgewood Area, Aberdeen Proving Ground, MD 210105424. TD11 CONFORMATIONAL ANALYSIS OF MUSTARD GAS HYDROLYSIS PRODUCTS

15 min

11:33

R. D. SUENRAM, D. F. PLUSQUELLIC, B. MATE´ , and A. R. HIGHT WALKER, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 208998441; J. O. JENSEN and A. C. SAMUELS, Passive Standoff Detection, Edgewood Chemical and Biological Center, Edgewood Area, Aberdeen Proving Ground, MD 210105424. TD12 OVERTONE SPECTROSCOPY AND DYNAMICS OF HCFC COMPOUNDS

10 min

11:50

X. CHEN, (Present address: Department of Chemistry, UC Berkeley, Berkeley 94720-1460, California, USA); A. MELCHIOR, Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; I. BAR, The Institutes for Applied Research, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; and S. ROSENWAKS, Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.

23

TE. INFRARED TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1153 SMITH LAB Chair: ROBERT McKELLAR, National Research Council of Canada, Ottawa, Canada TE01

15 min 10 THE INFRARED SPECTRUM OF THE B2 H6 BANDS IN THE BRIDGE B-H STRETCHING REGION

1:30

W. J. LAFFERTY, Optical Technology Division, NIST, Gaithersburg, MD 20899, USA; J.-M. FLAUD, Laboratoire de Photophysique Mol´eculaire, CNRS, Universit´e Paris-Sud, 91405, Orsay, Cedex, France; ¨ H. BURGER and G. PAWELKE, Anorganische Chemie, FB 9, Universita¨ t-GH, D-42097, Wuppertal, Germany. TE02 10 min 1:47 12 CD OH MOLECULE: A GOOD LASER SOURCE OF FAR-INFRARED RADIATION IN THE SPECTRAL RANGE 3 22 TO 3030 MICRONS E. C. C. VASCONCELLOS, Instituto de F´ısica ”Gleb Wataghin,” Departamento de Eletrˆonica Quˆantica, Universidade Estadual de Campinas (UNICAMP), 13083-970 Campinas, SP, Brazil; M. JACKSON, Department of Physics, University of Wisconson, LaCrosse, WI 54601; M. D. ALLEN and K. M. EVENSON, Time and Frequency Division, National Institute of Standards and Technology, Boulder, CO 80303-3328. TE03 15 min INDUCED ABSORPTION SPECTRA OF THE FUNDAMENTAL BAND OF D2 IN D2 -CO AND D2 -N2

1:59

G. VARGHESE, C. STAMP, and S. PADDI REDDY, Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John’s, Newfoundland, A1B 3X7, Canada. TE04 15 min 2:16 HELIUM DROPLET SPECTROSCOPY AS A TOOL FOR EXPLORING MOLECULAR AGGREGATION: VAN DER WAALS COMPLEXES OF HF WITH MULTIPLE H2 MOLECULES, PURE ORTHO-, PURE PARA- AND MIXED COMPLEXES DAVID T. MOORE, ROGER E. MILLER, Department of Chemistry, University of North Carolina, Chapel Hill NC, 27599. TE05 15 min 2:33 THE SPECTROSCOPY OF THE H2 -HF AND D2 -HF BINARY COMPLEXES IN LIQUID HELIUM DROPLETS DAVID T. MOORE, ROGER E. MILLER, Deptartment of Chemistry, University of North Carolina, Chapel Hill NC, 27599. TE06 15 min 2:50 QUANTUM SOLVATION: PATH INTEGRAL MONTE CARLO CALCULATIONS OF THE H2 -HF AND D2 -HF BINARY COMPLEXES IN LIQUID HELIUM DROPLETS DAVID T. MOORE, ROGER E. MILLER, Deptartment of Chemistry, University of North Carolina, Chapel Hill NC, 27599.

24

Intermission TE07 ABSOLUTE INTENSITIES MEASUREMENTS IN THE 4 WALLIS EFFECTS AND FORBIDDEN TRANSITIONS

+

10 min 3:30 12 5 BAND OF C2 H2 : ANALYSIS OF HERMAN-

J. VANDER AUWERA, Laboratoire de Chimie Physique Mol´eculaire C. P. 160/09, Universit´e Libre de Bruxelles, 50 avenue F. D. Roosevelt, B-1050 Brussels, Belgium. TE08 10 min 3:42 PRESSURE BROADENING, PRESSURE SHIFTS AND ABSOLUTE LINE INTENSITIES MEASUREMENTS IN THE 1 + 33 BAND OF 12 C2 H2 F. HERREGODTS, M. HEPP, D. HURTMANS, J. VANDER AUWERA, and M. HERMAN, Laboratoire de Chimie Physique Mol´eculaire C. P. 160/09, Universit´e Libre de Bruxelles, 50 avenue F. D. Roosevelt, B-1050 Brussels, Belgium. TE09 15 min 3:54 FTIR JET SPECTROSCOPY OF THE FUNDAMENTAL PARALLEL BANDS OF PERFLUOROCYCLOBUTANE IN THE MID-INFRARED THOMAS A. BLAKE, ROBERT L. SAMS, and STEVEN W. SHARPE, Pacific Northwest National Laboratory, P. O. Box 999, Mail Stop K8-88, 3020 Q Avenue, Richland, WA 99352 (PNNL is operated for the US Department of Energy by the Battelle Memorial Institute under contract DE-AC06-76RLO 1830). TE10 15 min 4:11 A COMBINED FREQUENCY ANALYSIS OF THE 3 , 9 , AND THE FAR INFRARED TORSIONAL SPECTRA OF ETHANE N. MOAZZEN-AHMADI, Department of Physics and Astronomy, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada, T2N 1N4. TE11 FUNDAMENTAL AND OVERTONE INTENSITIES FOR OH STRETCHING BANDS

15 min

4:28

K. R. LANGE, K. S. PLEGGE, N. P. WELLS, J. A. PHILLIPS, Department of Chemistry, University of Wisconsin - Eau Claire, Eau Claire, WI 54701. TE12 15 min SIMULTANEOUS VIBRATIONAL TRANSITIONS IN ABSORPTION SPECTRA OF BINARY SYSTEMS

4:45

A. AKHMEDJONOV, R. AKHMEDJONOV, and A. RASULOV, Samarkand State University, Samarkand, 703004, Uzbekistan. TE13 15 min 5:02 SIMULTANEOUS TRANSITIONS IN IR ABSORPTION SPECTRA OF SYSTEM CAPABLE TO THE COMPLEX FORMATION A. AKHMEDJONOV, U. RAHMATULLAEV, and I. RUSTAMOV, Samarkand State University, Samarkand, 703004, Uzbekistan.

25

TF. RADICALS AND IONS TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1009 McPHERSON LAB Chair: BOR-CHEN CHANG, National Central University, Chung-Li, Taiwan TF01 LIF EXCITATION SPECTROSCOPY OF 3-PENTOXY AND TERT-PENTOXY RADICALS

15 min

1:30

C.J. WANG, W. DENG, L. G. SHEMESH, M. D. LILIEN, D. R. KATZ and T. S. DIBBLE , Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, NY 13210.. TF02 JET-COOLED VIBRONIC SPECTROSCOPY OF VARIOUS ALKOXY RADICALS

15 min

1:47

JEFFREY R. ATWELL, CHRISTOPHER C. CARTER, SANDHYA GOPALAKRISHNAN, BRIAN E. APPLEGATE, AND TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210. TF03 FLASH PYROLYSIS IR LASER JET SPECTROSCOPY OF KETENE DERIVATIVES

15 min

2:04

R. J. LIVINGSTONE, Z. LIU and P. B. DAVIES, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom; N. R. HORE and D. K. RUSSELL, Department of Chemistry, University of Auckland, Private Bay 92019 Auckland 1, New Zealand. TF04 15 min 2:21 RYDBERG STATES OF ALLYL RADICAL OBSERVED BY ONE- AND TWO-PHOTON RESONANT IONIZATION SPECTROSCOPY JEN-CHIEH WU, RUNHUA LI, JIA-LIN CHANG and YIT-TSONG CHEN, Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, and Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan. TF05 THE ZEKE SPECTRA OF C3 H3 and C3 H5

15 min

2:38

THOMAS GILBERT,INGO FISCHER and PETER CHEN, Laboratorium f. Organische Chemie, ETH Zurich, CH-8092 Zurich, Switzerland..

Intermission TF06 15 min 3:10 ROVIBRONIC INTERACTIONS AND l-UNCOUPLING IN THE HIGH-RYDBERG STATES OF HCO CONVERGING TO THE (010) STATE OF THE CATION ¨ ERIC J. ZUCKERMAN, ROBERT J. FOLTYNOWICZ, JASON D. ROBINSON, HARTMUT G. HEDDERICH, and EDWARD R. GRANT, Department of Chemistry, Purdue University, West Lafayette, Indiana 47906.

26

TF07 15 min 3:27 THE EFFECTS OF INCREASED VIBRATIONAL AMPLITUDE ON ROVIBRONIC INTERACTIONS AND lUNCOUPLING IN THE HIGH-RYDBERG STATES OF HCO ¨ ROBERT J. FOLTYNOWICZ, JASON D. ROBINSON, and EDWARD R. GRANT, ERIC J. ZUCKERMAN, Department of Chemistry, Purdue University, West Lafayette, Indiana 47906. TF08 15 min 3:44 VIBRATIONAL SPECTROSCOPY OF A TRANSIENT SPECIES THROUGH TIME-RESOLVED FOURIER TRANSFORM IR EMISSION SPECTROSCOPY: THE VINYL RADICAL L. LETENDRE, and D.-K. LIU, Department of Chemistry, University of Pennsylvania, Philadelphia PA 19104; C. D. PIBEL , Department of Chemistry, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016; J. B. HALPERN, Department of Chemistry, Howard University, Washington, DC 20059; H.-L. DAI, Department of Chemistry, University of Pennsylvania, Philadelphia PA 19104. TF09 15 min 4:01 DETECTION OF TWO ISOMERS OF THE CYANOVINYL RADICAL: H2 CCCN AND CHCHCN BY FTMW SPECTROSCOPY J. TANG, K. SEIKI, Y. SUMIYOSHI, Y. ENDO, Department of Basic Sciences, The University of Tokyo, Komaba, Tokyo 153-8902, Japan; and Y. OHSHIMA, Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan. TF10 15 min 4:18 OBTAINING INFORMATION ON JAHN-TELLER ACTIVE SYSTEMS THROUGH ASYMMETRIC ISOTOPIC SUBSTITUTION: CASE OF CHD2 O AND CH2 DO METHOXY RADICALS ILIA J. KALINOVSKI, WAI Y. FAN, X. L. CHEN, C. BRADLEY MOORE, Chemical Sciences Division of the Lawrence Berkeley National Laboratory and Department of Chemistry, UC Berkeley, Berkeley 947201460, California, USA. TF11 15 min 4:35 DETECTION AND CHARACTERIZATION OF ALKYL PEROXY RADICALS USING CAVITY RINGDOWN SPECTROSCOPY MICHAEL PUSHKARSKY, SERGEY J. ZALYUBOVSKY, AND TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210. TF12 15 min 4:52 LABORATORY DETECTION OF A MOLECULAR BAND COINCIDENT WITH THE DIFFUSE INTERSTELLAR BAND AT 4428 C. D. BALL, M. C. MCCARTHY, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 and Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138. TF13 VIBRONIC SPECTROSCOPY OF CHLOROBENZYL RADICALS IN THE VISIBLE REGION

15 min

5:09

SANG KUK LEE, SANG YOUL CHAE, Department of Chemistry, Pusan National University, Pusan, 609735, South Korea.

27

TG. ELECTRONIC (SMALL) TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1000 McPHERSON LAB Chair: DONG-SHENG YANG, University of Kentucky, Lexington, KY TG01

15 min

1:30

XUV LASER PHOTOIONIZATION SPECTROSCOPY AT A RESOLUTION OF 0.008 CM 1 U. HOLLENSTEIN, G. C. L. PETRAGLIO, H. PALM, R. SEILER and F. MERKT, Laboratorium f¨ur Physikalische Chemie, Eidgen¨ossische Technische Hochschule, ETH-Zentrum, CH-8092 Zu¨ rich, Switzerland. TG02 15 min 1:47 PERTURBATIONS: THE (MODERATELY) HARD WAY TO OBSERVE CORE-NONPENETRATING RYDBERG STATES JASON O. CLEVENGER, XING JIANG, CHRISTOPHER M. GITTINS, and ROBERT W. FIELD, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139a . a This

research is supported by NSF Grant CHE97-30852.

TG03 RYDBERG STATES OF CALCIUM MONOCHLORIDE

15 min

2:04

JASON O. CLEVENGER, XING JIANG, SERGEY I. PANOV, and ROBERT W. FIELD, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139a . a This

research is supported by NSF Grant CHE97-30852.

TG04 15 min 2:21 NONLINEAR ABSORPTION IN JET-COOLED NO2 BY COMBINING THE CRDS AND LIF TECHNIQUES ´ ´ Grenoble High MagSYLVAIN HEILLIETTE, ANTOINE DELON, REMY JOST and PATRICK DUPRE, netic Field Laboratory, CNRS-MPI, BP 166, 25 Rue des Martyrs 38042 GRENOBLE,Cedex 9, France. TG05 JET-COOLED NO2 SPECTRUM AROUND THE DISSOCIATION THRESHOLD D0

( 25128 cm

15 min 1)

2:38

´ ´ Grenoble High MagSYLVAIN HEILLIETTE, ANTOINE DELON, REMY JOST and PATRICK DUPRE, netic Field Laboratory, CNRS-MPI, BP 166, 25 Rue des Martyrs 38042 GRENOBLE, Cedex 9, France. TG06 15 min 2:55 ROTATIONAL TEMPERATURE MEASUREMENTS OF AN OPTICALLY PUMPED, VIBRATIONALLY EXCITED CARBON MONOXIDE-ARGON PLASMA USING SINGLE PHOTON LASER INDUCED FLUORESCENCE OF THE (v00 = 20)X1 + (v0 = 2)D1 + BAND R. J. LEIWEKE and W. R. LEMPERT, Nonequilibrium Thermodynamics Laboratory, Department of Mechanical Engineering and Department of Chemistry, The Ohio State University, Columbus, OH 43210.

28

TG07

15 min 3:12 3 3 NEW RESULTS ON THE LOWEST LYING ELECTRONICALLY EXCITED STATES A2 AND B2 OF OZONE SABINE F. DEPPE, ALES CHARVAT, UWE WACHSMUTH, and BERND ABEL, Institut f¨ur Physikalische Chemie der Universit¨at G¨ottingen, Tammannstr. 6, 37077 G¨ottingen, Germany.

Intermission TG08 15 min 3:45 CALCULATING FRANCK-CONDON FACTORS FOR TRANSITIONS FROM LINEAR TO BENT STATES: APPLICATION TO THE ELECTRONIC SPECTRUM OF DIACETYLENE PAUL R. WINTER and TIMOTHY S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907; KEVIN K. LEHMANN, Department of Chemistry, Princeton University, Princeton, NJ 08544. TG09 e 2A THE X

1 TOGETHER

15 min 4:02 2 Ae B2 CONICAL INTERSECTION IN NO2 , OR HOW EXPERIMENTS AND THEORY INTERPLAY

´ ´ PATRICE THEULE, ´ ANTOINE DELON, Grenoble High Magnetic Field REMY JOST, PATRICK DUPRE, Laboratory, CNRS-MPI, BP 166, 25 Rue des Martyrs 38042 GRENOBLE, Cedex 9, France; MARCEL JACON, GSMA, UFR Sciences, BP 1037, 51687 REIMS Cedex 2, France. TG10 THE NEAR IR BULK and JET-COOLED NO2 SPECTRA by FTS, ICLAS, CRDS and LIF

15 min

4:19

´ ´ ANTOINE DELON, SYLVAIN HEILLIETTE, PATRICE THEULE, ´ REMY JOST, PATRICK DUPRE, Grenoble High Magnetic Field Laboratory, CNRS-MPI, BP 166, 25 Rue des Martyrs 38042 GRENOBLE, Cedex 9, France; ALAIN CAMPARGUE, GABRIELE WEIRAUCH, Laboratoire de Spectrom´etrie Physique, ` CNRS-Universit´e J. Fourier de Grenoble, BP 87, 38402 SAINT MARTIN D’HERES Cedex, France; JOHANNES ORPHAL, Laboratoire de Photophysique Mol´eculaire, CNRS-Universit´e Paris-Sud, Bˆat. 350, Centre d’Orsay, 91405 ORSAY Cedex, France; JOHN P. BURROWS, SABINE DREHER, Suzanne Voigt Institute of Environmental Physics and Remote-Sensing University of Bremen, PO Box 330440, 28334 BREMEN, Germany. TG11 HYPERFINE EFFECTS IN MAGNETIC ROTATION SPECTROSCOPY

15 min

4:36

CHRIS BOONE, Chemistry Department, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1. TG12

15 min

4:53 DOPPLER-FREE HIGH RESOLUTION SPECTRAL ATLAS OF IODINE MOLECULE 15,000 TO 19,000 CM 1 H. KATO, S. KASAHARA, M. MISONO, Department of Chemistry, Faculty of Science, Kobe University, 657-8501 Kobe, Japan; M. BABA, Faculty of Integrated Human Studies, Kyoto University, 606-8501 Kyoto, Japan.

29

TH. MICROWAVE TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1015 McPHERSON LAB Chair: SCOTT DAVIS, NIST, Gaithersburg, MD TH01 COMPARISON OF He AND H2 PRESSURE BROADENING OF NH3 FROM 15 TO 40 K

15 min

1:30

D. R. WILLEY, R. E. TIMLIN, M. DERAMO, P. L. PONDILLO, D. M. WESOLEK AND R. W. WIG, Department of Physics, Allegheny College, Meadville, PA 16335. TH02 THE ROTATIONAL TORSIONAL SPECTRUM OF THE 5 /29 DYAD OF NITRIC ACID

15 min

1:47

DOUGLAS T. PETKIE, Department of Physics, Ohio Northern University, Ada, OH 45810; THOMAS M. GOYETTE, University of Massachusetts, Submillimeter Technology Lab, 175 Cabot Street, Lowell, Massachusetts, 01854; SIEGHARD ALBERT, Laboratorium f¨ur Physikalische Chemie, ETH Z¨urich, CH-8092 Z¨urich Switzerland; PAUL HELMINGER, Department of Physics, University of South Alabama, Mobile, AL 36688; REBECCA A. H. BUTLER and FRANK C. DE LUCIA, Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, OH 43210-1106. TH03 MICROWAVE INVESTIGATION OF SULFURIC ACID MONOHYDRATE

15 min

2:04

D. L. FIACCO, S. W. HUNT, and K. R. LEOPOLD, Department of Chemistry, University of Minnesota, Minneapolis, MN 55455. TH04 10 min 2:21 THE SUBMILLIMETER-WAVE SPECTRUM OF TRANS- AND CIS-CROTONONITRILE (CH3 CH=CHCN) BRIAN J. DROUIN AND JOHN C. PEARSON, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099. TH05 THE PURE ROTATIONAL SPECTRA OF LANTHANUM MONOHALIDES

15 min

2:33

DARYL S. RUBINOFF, COREY J. EVANS and MICHAEL C. L. GERRY, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B. C., Canada, V6T 1Z1. TH06 15 min 2:50 MICROWAVE SPECTRA AND MOLECULAR STRUCTURE OF ACETYLENEMETHYLDIOXORHENIUM, A RHENIUM METALACYCLOPROPENEa STEPHEN KUKOLICH, BRIAN DROUIN, OLIVER INDRIS AND JENNIFER DANNEMILLER, Department of Chemistry, University of Arizona, Tucson, AZ 85721 (Present Address for B. Drouin: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109); JOCHEN ZOLLER and WOLFGANG HERRMANN, Anorganisch-Chemisches Institut der Technischen Universit a¨ t M¨unchen, Lichtenbergstrasse 4, D-85747 Garching bei Mu¨ nchen, Germany. a Supported

by THE NATIONAL SCIENCE FOUNDATION

30

TH07 15 min 3:07 EXTENSION OF TIME-RESOLVED DOUBLE RESONANCE STUDIES OF ROTATIONAL ENERGY TRANSFER TO AN OBLATE SYMMETRIC ROTOR MATTHEW M. BEAKY, Department of Physics, Duke University, Durham, NC 27708; DAVID D. SKATRUD, Physics Division, U.S. Army Research Office, RTP, NC 27709.

Intermission TH08 15 min 3:40 SUBMILLIMETER WAVE ABSORPTION SPECTROSCOPY OF PSEUDOROTATIONAL TRANSITIONS IN TETRAHYDROFURAN DMITRY G. MELNIK, SANDHYA GOPALAKRISHNAN, TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210; and FRANK C. DE LUCIA, The Ohio State University, Dept. of Physics, Microwave Laboratory, 174 W. 18th Avenue, Columbus OH 43210.

TH09 ROTATIONAL SPECTROSCOPY TETRAHYDROFURAN

AND

RING-PUCKERING

CONFORMATION

OF

15 min 3:57 3-HYDROXY-

RICHARD J. LAVRICH, RACHELE L. RHEA, JAMES W. McCARGAR, and MICHAEL J. TUBERGEN, Department of Chemistry, Kent State University, Kent, OH 44242.

TH10 15 min 4:14 VAN DER WAALS COMPLEXES OF 3-HYDROXYTETRAHYDROFURAN: 3-HYDROXYTETRAHYDROFURANH2 O AND 3-HYDROXYTETRAHYDROFURAN-Ar RICHARD J. LAVRICH, CHARLES R. TOROK, and MICHAEL J. TUBERGEN, Department of Chemistry, Kent State University, Kent, OH 44242.

TH11 MICROWAVE INVESTIGATION OF FOR THIS MOLECULE

15 min 4:31 CIS; T RANS -1,4-DIFLUOROBUTADIENE AND A PARTIAL STRUCTURE

RICHARD J. LAVRICH and MICHAEL J. TUBERGEN, Department of Chemistry, Kent State University, Kent, OH 44242; NORMAN C. CRAIG and CATHERINE M. OERTEL, Department of Chemistry, Oberlin College, Oberlin, OH 44074.

TH12 10 min 4:48 ROTATIONAL SPECTRA AND INTERNAL ROTATION OF 1,1,1,2,2-PENTAFLUOROPROPRANE AND 2,2,2TRIFLUOROETHYLMETHYLETHER N. SAKAKIBARA, K. FUCHIGAMI, Y. TATAMITANI, T. OGATA, Department of Chemistry, Faculty of Science, Shizuoka University, Shizuoka, Japan 422-8529.

31

TH13 GAS PHASE STRUCTURE OF TRIFLUOROACETYL PEROXYNITRATE.

10 min

5:00

ANGELIKA HERMANN, JAN NIEMEYER, HANS-GEORG MACK, DINES CHRISTEN, and HEINZ OBERHAMMER, Institute of Physical and Theoretical Chemistry, University of Tu¨ bingen, Germany; HELGE ¨ WILLNER, Institute of Synthetic Chemistry, University of Duisburg, Germany; MARTIN SCHAFER and ALFRED BAUDER, Laboratory of Physical Chemistry, ETH, Z¨urich, Switzerland. TH14 10 min 5:12 THE MICROWAVE SPECTRUM OF 1,2,4-TRIAZINE AND THE ROTATIONAL CONSTANTS OBTAINED FROM A SIMULTANEOUS ANALYSIS OF MICROWAVE GROUND STATE AND HIGH RESOLUTION IR-TRANSITIONS. DINES CHRISTEN, Institute of Physical and Theoretical Chemistry, University of T¨ubingen, Germany; MICHAEL H. PALMER, Department of Chemistry, University of Edinburgh, Scotland, UK; FLEMMING HEGELUND, Department of Chemistry, Aarhus University, Denmark. TH15 PROGRESS REPORT ON THE STUDY OF THE AMINO AMIDE VALINAMIDE

10 min

5:24

RICHARD J. LAVRICH, CHARLES R. TOROK, and MICHAEL J. TUBERGEN, Department of Chemistry, Kent State University, Kent, OH 44242.

32

TI. THEORY TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1005 SMITH LAB Chair: PETER BOTSCHWINA, Universit¨at G¨ottingen, G¨ottingen, Germany TI01 15 min 1:30 K-SCRAMBLING IN A NEAR-SYMMETRIC-TOP MOLECULE CONTAINING AN EXCITED NON-COAXIAL INTERNAL ROTOR JUAN ORTIGOSO, Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cient´ıficas, Serrano 121, 28006 Madrid, Spain; JON T. HOUGEN, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441. TI02 IVR SCALING OF THE INTERNAL ROTOR

15 min

1:47

RYAN PEARMAN and MARTIN GRUEBELE, Beckman Institute for Advanced Science and Technology and Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801. TI03 15 min DYNAMICAL STUDY OF TRIMETHYLAMINE BY MEANS OF THE NON-RIGID GROUP THEORY

2:04

Y. G. SMEYERS, Instituto de Estructura de la Materia, C.S.I.C, Serrano 113-bis, 28006-Madrid, SPAIN. ; and M. VILLA, Departamento de Quimica, Universidad Autonoma Metropolitana - I., 09340, D. F., MEXICO.. TI04 15 min 2:21 INFLUENCE OF THE VIBRATIONAL ZERO POINT CORRECTION ON THE AMINE INVERSION BARRIER AND THE FIR SPECTRUM OF METHYLAMINE Y. G. SMEYERS, Instituto de Estructura de la Materia, C.S.I.C, Serrano 113-bis, 28006-Madrid, SPAIN. ; and M. VILLA, Departamento de Quimica, Universidad Autonoma Metropolitana - I., 09340, D. F., MEXICO.. TI05 CURVILINEAR INTERNAL VALENCE COORDINATE HAMILTONIAN FOR AMMONIA

15 min

2:38

JANNE PESONEN, ANDREA MIANI, Laboratory of Physical Chemistry, P.O. Box 55 (A. I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland; LAURI HALONEN, JILA, University of Colorado, Campus Box 440, Boulder, Colorado 80309. TI06 15 min 2:55 THEORETICAL STUDY OF THE METHANE STRETCHING VIBRATIONAL ENERGY LEVEL STRUCTURE CLOSE TO A NICKEL SURFACE LAURI HALONEN AND DAVID NESBITT, JILA, University of Colorado, Campus Box 440, Boulder, Colorado 80309.

33

TI07 ANTIGRAVITATION QUANTUM HIGH ENERGY KHOLMURAD KHASANOV, [email protected].

Samarkand State University,

15 min

Uzbekistan,

703004,

email:

3:12

han-

Intermission TI08 15 min 3:45 DIRECT TWO QUANTUM JUMPS IN HIGH FREQUENCY ELECTRON PARAMAGNETIC RESONANCE DESCRIBED BY A 3-LEVEL DENSITY MATRIX FORMALISM. W. LEO MEERTS, Department of Molecular and Laser Physics, University of Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands; PAUL J.M. van KAN, Department of Molecular Spectroscopy, University of Nijmegen; ETIENNE GOOVAERTS, Department of Physics, University of Antwerp, UIA campus, 2610 Wilrijk, Belgium. TI09 15 min 4:02 DIFFUSION QUANTUM MONTE CARLO ON MULTIPLE POTENTIAL SURFACES: A SCALABLE APPROACH FOR CALCULATING SHIFTS IN TRANSITION FREQUENCIES IN CLUSTERS ANNE B. McCOY, Department of Chemistry, The Ohio State University, Columbus, OH, 43210. TI10 NONEXPONENTIAL DEPHASING IN QUANTUM MECHANICAL SYSTEMS

15 min

4:19

V. WONG and M. GRUEBELE, Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois,Urbana IL 61801. TI11 15 min 4:36 ANGULAR MOMENTUM TRANSFER IN ROTATIONAL ENERGY TRANSFER: TESTS OF GENERALIZED SCALING LAWS APPLIED TO O2 STEPHEN L. COY, K. RYBAK, J. I. STEINFELD, MIT Department of Chemistry, Cambridge, MA 02139. TI12

15 min

~ 2 ; vXH BOUND ROVIBRATIONAL ENERGY LEVELS FOR THE NeXH/D (X COMPLEXES

4:53

= 0; X = O; S ) VAN DER WAALS

HEE-SEUNG LEE and ANNE B. McCOY, Department of Chemistry, The Ohio State University, Columbus, OH 43210. TI13 15 min FINGERPRINTS OF SADDLE-NODE BIFURCATION IN SPECTRUM AND DISSOCIATION OF HOCl

5:10

S. GREBENSHCHIKOV, J. WEISS, J. HAUSCHILDT, and R. SCHINKE, MPI f¨ur Str¨omungsforschung Bunsenstraße 10, D-37073 G¨ottingen, Germany.

34

WA. PLENARY WEDNESDAY, JUNE 14, 2000 – 8:45 AM Room: AUDITORIUM INDEPENDENCE HALL Chair: BRUCE BURSTEN, The Ohio State University, Columbus, OH WA01 40 min 8:45 JET COOLED LASER SPECTROSCOPY OF HYDROCARBON RADICALS AND MOLECULAR IONS IN SLIT SUPERSONIC EXPANSIONS DAVID J.NESBITT, SCOTT DAVIS, MICHAL FARNIK, DAIRENE UY, MARJO HALONEN, AND PINGRONG YU, JILA, National Institute for Standards and Technology, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, 80309. WA02 40 min 9:30 HIGH-RESOLUTION ELECTRON AND PHOTOELECTRON SPECTROSCOPY IN THE EXTREME ULTRAVIOLET (XUV) F. MERKT, Laboratorium f¨ur Physikalische Chemie, Eidgen¨ossische Technische Hochschule, ETH-Zentrum, CH-8092 Z¨urich, Switzerland.

Intermission WA03 40 min 10:30 MOLECULAR BEAM SPECTROSCOPIC STUDIES OF TRANSITION METAL CONTAINING RADICALS TIMOTHY C. STEIMLE, Department of Chemistry and Biochemistry, Arizona State University, Tempe, Az, 85287-1604. WA04 40 min 11:15 SUBMILLIMETER AND MID/FAR-INFRARED SPECTROSCOPY IN INTERSTELLAR AND CIRCUMSTELLAR CLOUDS JOSE CERNICHARO, CSIC. IEM. Dpt. Molecular Physics. C/Serrano 121. 28006 Madrid. Spain. email:[email protected].

35

WE. MICROWAVE WEDNESDAY, JUNE 14, 2000 – 1:30 PM Room: 1153 SMITH LAB Chair: KEN LEOPOLD, University of Minnesota, Minneapolis, MN WE01 MILLIMETER WAVE SPECTRA OF THE H2 -H2 O VAN DER WAALS COMPLEX

15 min

1:30

CHRISTOPHER WHITHAM, KENSUKE HARADA and KEIICHI TANAKA, Institute for Molecular Science, Myodaiji, Okazaki 444-8585 Japan. WE02 FT MICROWAVE SPECTROSCOPY OF THE H2 O-O2 COMPLEX

10 min

1:47

YASUKO KASAI, Millimeter-Wave Remote Sensing Section, Global Environment Division Communication Research laboratory, Tokyo 184-8795, Japan; YOSHIHIRO SUMIYOSHI, and YASUKI ENDO, Depertment of Pure and Applied Sciences, College of Art and Sciences, The University of Tokyo, Tokyo 153-8902, Japan. WE03 15 min 1:59 MICROWAVE SPECTRUM AND STRUCTURE OF THE OPEN-SHELL VAN DER WAALS COMPLEX Ar–ClO2 ¨ MARTIN SCHAFER, Laboratorium f¨ur Physikalische Chemie, ETH Zentrum, CH-8092 Z¨urich, Switzerlanda . a Present

address: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260.

WE04 VIBRATION-ROTATIONAL-TUNNELING (10 ,n=0) (00 , n=0) TRANSITION IN Ar
ND3

15 min

2:16

SANDHYA GOPALAKRISHNAN, DMITRY G. MELNIK, TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210; and FRANK C. DE LUCIA, The Ohio State University, Dept. of Physics, Microwave Laboratory, 174 W. 18th Avenue, Columbus OH 43210. WE05 ROTATIONAL SPECTROSCOPY OF OCS–N2 O

15 min

2:33

OLAYINKA A. OYEYEMI, HELEN O. LEUNG, Department of Chemistry, Mount Holyoke College, South Hadley, MA 01075. WE06 15 min 2:50 VAN DER WAALS BENDING BAND OF THE ArDCN CLUSTER OBSERVED BY MILLIMETER-WAVE SPECTROSCOPY COMBINED WITH A PULSED SUPERSONIC-JET TECHNIQUE KEIICHI TANAKA, S. BAILLEUX, A. MIZOGUCHI, and K. HARADA, Institute for Molecular Science, Okazaki, 444-8585, Japan.

36

WE07 15 min 3:07 MILLIMETER-WAVE SPECTROSCOPY FOR VAN DER WAALS BENDING HOT BANDS OF THE Ar-HCN COMPLEX A. MIZOGUCHI, S. BAILLEUX, K. HARADA, and K. TANAKA, Department of Applied Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan.

Intermission WE08 15 min 3:40 EVIDENCE FOR NOBLE GAS-METAL CHEMICAL BONDING: FT-MICROWAVE SPECTRA, GEOMETRIES AND HYPERFINE CONSTANTS OF THE COMPLEXES Ar-CuX (X=F, Cl, Br). COREY J. EVANS and MICHAEL C. L. GERRY, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B. C., Canada, V6T 1Z1. WE09 15 min MICROWAVE SPECTRA, STRUCTURES AND HYPERFINE CONSTANTS OF GOLD(I) HALIDES.

3:57

COREY J. EVANS, LINDA REYNARD and MICHAEL C. L. GERRY, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B. C., Canada, V6T 1Z1. WE10 15 min 4:14 CHEMICAL BONDING BETWEEN Ar/Kr AND Au: FTMW SPECTRA, GEOMETRIES AND HYPERFINE CONSTANTS OF THE COMPLEXES Ar-AuX (X=F,Cl,Br) AND Kr-AuCl. COREY J. EVANS, DARYL S. RUBINOFF and MICHAEL C. L. GERRY, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B. C., Canada, V6T 1Z1; ALBERTO LESARRI, Departamento de Quimica Fisica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid, Spain. WE11 15 min 4:31 MICROWAVE SPECTRA, STRUCTURES AND MODELING OF THE N2 O-SO2 AND N2 O-N2 O-SO2 COMPLEXES REBECCA A. PEEBLES and ROBERT L. KUCZKOWSKI, Department of Chemistry, University of Michigan, 930 N. University Ave., Ann Arbor, MI 48109-1055. WE12 ROTATIONAL SPECTRA OF THE AR-AR-NH3 AND NE-NE-NH3 VAN DER WAALS TRIMERS

15 min

4:48

¨ JENNIFER VAN WIJNGAARDEN and WOLFGANG JAGER, Department of Chemistry, University of Alberta, Edmonton, AB, Canada, T6G 2G2. WE13 15 min 5:05 FOURIER TRANSFORM MICROWAVE SPECTROSCOPIC INVESTIGATION OF CARBONYLSULFIDE LOOSELY BOUND TO TWO HELIUM ATOMS ¨ YUNJIE XU and WOLFGANG JAGER, Department of Chemistry, University of Alberta, Edmonton, AB, Canada, T6G 2G2.

37

WF. ELECTRONIC (SMALL) WEDNESDAY, JUNE 14, 2000 – 1:30 PM Room: 1009 SMITH LAB Chair: TIMOTHY STEIMLE, Arizona State University, Tempe, AZ WF01 FOURIER TRANSFORM EMISSION SPECTROSCOPY OF THE A 2 

10 min 1:30 2 + X  TRANSITION OF ZINC HYDRIDE

T. HIRAO and P. F. BERNATH, Department of Chemistry, University of Waterloo, Waterloo, Ontario, CANADA N2L 3G1. WF02 LASER SPECTROSCOPY OF THE B 2 +

10 min

1:42

X 2 + TRANSITION OF ZrN AND TiN

HONGBING CHEN, YONGFANG LI, and A. S-C. CHEUNG, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong. WF03 THE ROTATIONALLY RESOLVED NEAR INFRARED BAND SYSTEMS OF TiCo AND ZrCo

10 min

1:54

S. M. SICKAFOOSE, M. D. MORSE, Department of Chemistry, University of Utah, Salt Lake City, UT 84112; and D. A. HALES, Department of Chemistry, Hendrix College, Conway, AR 72032. WF04 RADIATIVE LIFETIMES OF NiH AND CoH

15 min

2:06

15 min

2:23

JENNIFER GOTTFRIED and JEFFREY A. GRAY, Department of Chemistry, Ohio Northern University, Ada, OH 45810. WF05 HIGH RESOLUTION LASER SPECTROSCOPY OF THE A0+

X 0+ SYSTEM OF YbS

TODD C. MELVILLE, JOHN A. COXON, Department of Chemistry, Dalhousie University, Halifax, NS, Canada B3H 4J3; COLAN LINTON, Physics Department, University of New Brunswick, P.O. Box 4400, Fredericton, NB, Canada E3B 5A3. WF06 ELECTRONIC TRANSITIONS OF TUNGSTEN MONOXIDE

10 min

2:40

GANG LI, TSUYOSHI HIRAO, and PETER F. BERNATH, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. WF07 FOURIER TRANSFORM SPECTROSCOPY OF BaO: ANALYSIS OF A 1 +

10 min 2:52 1 + X  CHEMILUMINESCENCE

HONGZHI LI, CRISTIAN FOCSA, BERNARD PINCHEMEL, PETER F. BERNATH and ROBERT J. LE ROY, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

38

WF08 THE A 1 +

X 1 + AND A0 1 

10 min 3:04 1 + X  CHEMILUMINESCENCE SPECTRA OF SrO FROM A FOURIER TRANS-

FORM SPECTROMETER HONGZHI LI, RANDALL SKELTON, CRISTIAN FOCSA, BERNARD PINCHEMEL, and PETER F. BERNATH, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

Intermission WF09 MOLECULAR BEAM STUDY OF THE 6 

15 min

3:30

X 6
ELECTRONIC TRANSITION IN FeCl

JIE LEI, and PAUL J. DAGDIGIAN, Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218-2685, USA. WF10 THE ULTRAVIOLET SPECTRUM OF THE FeF RADICAL

15 min

3:47

STEPHEN M. KERMODE and JOHN M. BROWN, The Physical and Theoretical Chemistry Laboratory, South Parks Road, Oxford, OX1 3QZ, United Kingdom. WF11 15 min 4:04 HIGH RESOLUTION FOURIER TRANSFORM UV EMISSION SPECTROSCOPY OF THE 407 NM BAND OF THE TiF RADICAL TAKASHI IMAJO, YUKI KOBAYASHI, YOSHIHIRO NAKASHIMA, KEIICHI TANAKA, AND TAKEHIKO TANAKA, Department of Chemistry, Faculty of Science, Kyushu University 33, Hakozaki, Higashi ku, Fukuoka 812-8581, Japan.; ,. WF12 THE NEAR INFRARED SYSTEMS OF NICKEL CHLORIDE

10 min

4:21

LEAH O’BRIEN, TENEIL KELLERMAN, and AMANDA LAMBETH, Department of Chemistry, Southern Illinois University, Edwardsville, IL 62026-1652. WF13 INTRACAVITY LASER SPECTROSCOPY OF NICKEL CHLORIDE: SYSTEM I

10 min

4:33

JAMES J. O’BRIEN and HONG CAO, Department of Chemistry, University of Missouri, St. Louis, MO 63121-4499; LEAH O’BRIEN, Department of Chemistry, Southern Illinois University, Edwardsville, IL 62026-1652. WF14 HIGH RESOLUTION SPECTROSCOPY AND AB INITIO CALCULATIONS ON HfCl

15 min

4:45

R. S. RAM, Department of Chemistry, University of Arizona, Tucson, AZ 85721; A. G. ADAM, Department of ´ Chemistry University of New Brunswick, Fredericton, N.B., Canada E3B 6E2; A. TSOULI, J. LI EVIN, Universit´e Libre de Bruxelles, Laboratoire de Chimie Physique Mol´eculaire, CP 160/09, Av. F. D. Roosevelt 50, Bruxelles, Belgium; P. F. BERNATH, Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.

39

WF15 THE VISIBLE AND ULTRAVIOLET SPECTRUM OF SILVER CHLORIDE

10 min

5:02

LEAH O’BRIEN, TENEIL KELLERMAN, and AMANDA LAMBETH, Department of Chemistry, Southern Illinois University, Edwardsville, IL 62026-1652.

40

WG. INFRARED WEDNESDAY, JUNE 14, 2000 – 1:30 PM Room: 1000 McPHERSON Chair: ARTHUR MAKI, Mill Creek, WA

WG01 THE ATMOSPHERIC CHEMISTRY EXPERIMENT (ACE)

15 min

1:30

CHRIS BOONE, RANDALL SKELTON, SEAN MCLEOD AND PETER BENATH, Chemistry Department, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1.

WG02

10 min

1:47

˚ AND B- (NEAR 6880 A) ˚ BANDS QUANTITATIVE PARAMETERS FOR SOME LINES IN THE O2 A- (NEAR 7620 A) OBTAINED BY INTRACAVITY LASER SPECTROSCOPY JAMES J. O’BRIEN and HONG CAO, Department of Chemistry, University of Missouri-St. Louis, St. Louis, MO 63121-4499.

WG03 HIGH RESOLUTION SPECTRA OF ISOTOPIC OZONE IN THE 5 m REGION

10 min

1:59

M. A. H. SMITH, C. P. RINSLAND, Atmospheric Sciences, NASA Langley Research Center, Mail Stop 401A, Hampton, VA 23681-2199; V. MALATHY DEVI, D. CHRIS BENNER, Department of Physics, The College of William and Mary, Box 8795, Williamsburg, VA 23187-8795; T. M. STEPHEN, A. GOLDMAN, Department of Physics and Astronomy, University of Denver, 2112 E. Wesley Ave., Denver, CO 80208-0202; and A. PERRIN, Laboratoire de Photophysique Mol´eculaire, Universit´e de Paris-Sud, Campus Orsay Bˆat. 350, 91405 ORSAY Cedex - France.

WG04

15 min

2:11

LINE PARAMETERS OF WATER BETWEEN 9650 AND 11400 cm 1 L. R. BROWN and R. A. TOTH, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109; M. DULICK, National Solar Observatory, Tucson, AZ 85726.

WG05 15 min 2:28 THE 31 OVERTONE BAND OF HONO: ROVIBRATIONAL PARAMETERS AND BAND INTENSITY USING INTRACAVITY LASER ABSORPTION SPECTROSCOPY S.K. WITONSKY, M.R. CANAGARATNA, S.L. COY, J.I. STEINFELD, and R.W. FIELD, Department of Chemistry and G.R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139; A.A. KACHANOV, Laboratoire de Spectrom´etrie Physique – CNRS UMR 5588, Universit´e J. Fourier–Grenoble I, B.P. 87 – 38402 Saint Martin d’H`eres Cedex, France.

41

WG06 ABSOLUTE LINE INTENSITIES MEASUREMENTS IN THE 2 BAND OF HOCl

10 min

2:45

J. VANDER AUWERA, Laboratoire de Chimie Physique Mol´eculaire C. P. 160/09, Universit´e Libre de Bruxelles, 50 avenue F. D. Roosevelt, B-1050 Brussels, Belgium; J. KLEFFMANN, Physikalische Chemie, FB 9, Universit¨at-GH Wuppertal, D-42097 Wuppertal, Germany; J-M. FLAUD, Laboratoire de Photophysique Mol´eculaire, CNRS, Universit´e de Paris-Sud, Campus d’Orsay, Bˆat. 210, F-91405 Orsay Cedex, France; G. ¨ PAWELKE and H. BURGER, Anorganische Chemie, FB 9, Universita¨ t-GH Wuppertal, D-42097 Wuppertal, Germany.

WG07

10 min 2:57 14 16 ABSOLUTE LINE INTENSITIES IN THE 2 m REGION OF N2 O AND THEIR TREATMENT USING THE EFFECTIVE DIPOLE MOMENT APPROACH L. DAUMONT, J-L. TEFFO, Laboratoire de Physique Mol´eculaire et Applications, CNRS, Boˆıte 76, Universit´e Pierre et Marie Curie, 4 Place Jussieu, F-75252 Paris-Cedex 05, France; J. VANDER AUWERA, Laboratoire de Chimie Physique Mol´eculaire C. P. 160/09, Universit´e Libre de Bruxelles, 50 avenue F. D. Roosevelt, B-1050 Brussels, Belgium; V. I. PEREVALOV and S. A. TASHKUN, Institute of Atmospheric Optics, Russian Academy of Sciences, Siberian Branch, 1 Akademicheskii avenue, 634055 Tomsk, Russia.

Intermission WG08

10 min

3:30

˚ REGION ABSORPTION SPECTRA AND ABSORPTION COEFFICIENTS FOR METHANE IN THE 7515 - 9205 A OBTAINED BY INTRACAVITY LASER SPECTROSCOPY JAMES J. O’BRIEN and HONG CAO, Department of Chemistry, University of Missouri-St. Louis, St. Louis, MO 63121-4499.

WG09 15 min 3:42 TEMPERATURE DEPENDENCE OF LINE MIXING IN THE P BRANCH OF THE 3 BAND OF METHANE D. CHRIS BENNER, V. MALATHY DEVI, Department of Physics, The College of William and Mary, Box 8795, Williamsburg, VA 23187-8795; MARY ANN H. SMITH, CURTIS P. RINSLAND, Atmospheric Sciences, NASA Langley Research Center, Mail Stop 401A, Hampton, VA 23681-2199; GUY GUELACHVILI, ´ Laboratoire de Photophysique Moleculaire, CNRS, Universit´e de Paris Sud, Campus NATHALIE PICQUE, d’Orsay, Bˆatiment 350, 91405 ORSAY-Cedex, France; and LINDA R. BROWN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109.

WG10

15 min

3:59 12 NITROGEN BROADENING AND SHIFT COEFFICIENTS IN THE 5 AND 6 FUNDAMENTAL BANDS OF CH3 D V. MALATHY DEVI, D. CHRIS BENNER, Department of Physics, The College of William and Mary, Box 8795, Williamsburg, VA 23187-8795; M. A. H. SMITH, C. P. RINSLAND, Atmospheric Sciences, NASA Langley Research Center, Mail Stop 401A, Hampton, VA 23681-2199; L. R. BROWN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109; and R. L. SAMS, Pacific Northwest National Laboratory (PNNL), P.O.Box 999, Mail Stop K8-88, Richland, WA 99352.

42

WG11

15 min 12 ANALYSIS OF SELF-BROADENED SPECTRA IN THE 5 AND 6 FUNDAMENTAL BANDS OF CH3 D

4:16

L. R. BROWN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109; V. MALATHY DEVI, D. CHRIS BENNER, Department of Physics, The College of William and Mary, Box 8795, Williamsburg, VA 23187-8795; M. A. H. SMITH, C. P. RINSLAND, Atmospheric Sciences, NASA Langley Research Center, Mail Stop 401A, Hampton, VA 23681-2199; and R. L. SAMS, Pacific Northwest National Laboratory (PNNL), P.O.Box 999, Mail Stop K8-88, Richland, WA 99352. WG12 15 min 4:33 NITROGEN- AND SELF-BROADENING AND SHIFT COEFFICIENTS IN THE 3 FUNDAMENTAL BAND OF 12 CH D 3 M. A. H. SMITH, C. P. RINSLAND, Atmospheric Sciences, NASA Langley Research Center, Mail Stop 401A, Hampton, VA 23681-2199; V. MALATHY DEVI, D. CHRIS BENNER, Department of Physics, The College of William and Mary, Box 8795, Williamsburg, VA 23187-8795; and L. R. BROWN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109. WG13

15 min

4:50

LINE MIXING IN THE TRIAD OF 12 CH3 D D. CHRIS BENNER, V. MALATHY DEVI, Department of Physics, The College of William and Mary, Box 8795, Williamsburg, VA 23187-8795; L. R. BROWN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109; M. A. H. SMITH, and C. P. RINSLAND, Atmospheric Sciences, NASA Langley Research Center, Mail Stop 401A, Hampton, VA 23681-2199. WG14 10 min 5:07 EXPERIMENTAL STUDY OF DEVIATION FROM LORENTZIAN SHAPE OF COLLISIONAL BROADENED SPECTRAL LINES IN MILLIMETER AND SUBMILLIMETER WAVE BANDS GUERMAN Yu. GOLUBYATNIKOV, VLADIMIR N. MARKOV, Applied Physics Institute of RAS, 46 Ul’yanova str., GSP-120, Nizhny Novgorod 603600, Russia; ANTONIO GUARNIERI and HEINRICH ¨ J. MADER, Institut f¨ur Physikalische Chemie der Universita¨ t Kiel, Olshausenstr. 40, D–24098 Kiel.

43

WH. VIBRONIC INTERACTIONS WEDNESDAY, JUNE 14, 2000 – 1:30 PM Room: 1015 McPHERSON LAB Chair: WOLFGANG ERNST, Pennsylvania State University, University Park, PA WH01 Invited Talk 30 min ORBITAL ANGULAR MOMENTUM IN LINEAR MOLECULES CONTAINING TRANSITION METALS

1:30

ANTHONY J. MERER, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B.C. V6T 1Z1, Canada. WH02 A VARIATIONAL TREATMENT OF THE RENNER-TELLER EFFECT

15 min

2:05

P. R. BUNKER and G. OSMANN, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada; PER JENSEN, FB 9 - Theoretische Chemie, Bergische Universit¨at - Gesamthochschule Wuppertal, D-42097 Wuppertal, Germany.. WH03 SEEING MOLECULES USING COULOMB EXPLOSION IMAGING

15 min

2:22

P. R. BUNKER and G. OSMANN, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada; W. P. KRAEMER, Max Planck Institute for Astrophysics, D-85740 Garching, Germany.; PER JENSEN, FB 9 - Theoretische Chemie, Bergische Universit a¨ t Gesamthochschule Wuppertal, D-42097 Wuppertal, Germany.. WH04

15 min 2:39 3 COMPARATIVE ANALYSIS OF THE RENNER EFFECT IN THE A~  STATE OF CCO, CSiO, SiCO, AND SiSiO WITH EQUATION OF MOTION COUPLED CLUSTER THEORY (EOM-CCSD) SHAWN T. BROWN, NICOLAS D. K. PETRACO, YUKIO YAMAGUCHI, and HENRY F. SCHAEFER, Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602. WH05 15 min 2:56 FOURIER TRANSFORM SPECTRA OF COPPER DICHLORIDE : RENNER-TELLER EFFECT IN ROVIBRONIC LEVELS OF THE GROUND STATE P. CROZET, E. BOSCH, A. J. ROSS, Laboratoire de Spectrom´etrie Ionique et Mol´eculaire (UMR 5579 CNRS), Bˆatiment 205, Universit´e Lyon I, Campus la Doua, 69622 Villeurbanne Cedex, France; and J. M. BROWN, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, England.

Intermission WH06 Invited Talk 30 min 3:30 MULTI-MODE DYNAMICAL JAHN-TELLER EFFECTS IN MOLECULAR ELECTRONIC SPECTRA AND INTERNAL CONVERSION DYNAMICS ¨ HORST KOPPEL, Theoretical Chemistry, University of Heidelberg, INF 229, D-69120 Heidelberg, Germany.

44

WH07

15 min

4:05 RENNER-TELLER COUPLING IN OPEN-SHELL COMPLEXES: THE ROVIBRONIC STRUCTURE OF CH(A2
)Ne GALINA KERENSKAYA, ALEXEY L. KALEDIN, and MICHAEL C. HEAVEN, Department of Chemistry, Emory University, Atlanta, GA 30322. WH08 10 min 4:22 LARGE-SCALE COUPLED CLUSTER CALCULATIONS FOR THE TWO RENNER-TELLER COMPONENTS OF HCCO P. BOTSCHWINA, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany. WH09

15 min 4:34 2 THE RENNER-TELLER EFFECT FOR THE  ELECTRONIC EXCITED STATE OF MgCN; AN AB INITIO MOLECULAR ORBITAL PREDICTION ERIKA ODAKA, TETSUYA TAKETSUGU, TSUNEO HIRANO, Department of Chemistry, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan; UMPEI NAGASHIMA, National Institute for Advanced Interdisciplinary Research, Ibaraki 305-8562, Japan.

45

WI. MATRIX WEDNESDAY, JUNE 14, 2000 – 1:30 PM Room: 1005 SMITH LAB Chair: TAKAMASA MOMOSE, Kyoto University, Kyoto, Japan

WI01 SPECTROSCOPY OF CHLORINE MONOFLUORIDE ISOLATED IN RARE GAS MATRICES

15 min

1:30

M. BARGHEER, P. DIETRICH and N. SCHWENTNER, Institut f¨ur Experimentalphysik, Freie Universita¨ t Berlin, Arnimallee 14, 14195 Berlin, Germany.

WI02 15 min FTIR ISOTOPIC STUDY OF C-C STRETCHING MODES OF THE C12 CHAIN TRAPPED IN SOLID Ar

1:47

X.D. DING, S.L. WANG, C.M.L. RITTBY, and W.R.M. GRAHAM, Department of Physics and Astronomy, TCU, Fort Worth, TX 76129.

WI03

15 min

2:04

THE INFRARED SPECTRUM OF H2 O2 + TRAPPED IN SOLID NEON CATHERINE L. LUGEZ, WARREN E. THOMPSON, and MARILYN E. JACOX, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441.

WI04 15 min 2:21 INFRARED SPECTRA OF THE PRODUCTS OF THE PHOTODISSOCIATION AND PHOTOIONIZATION OF NCCN, ClCN, AND BrCN AT 16.6-16.85 eV WARREN E. THOMPSON and MARILYN E. JACOX, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441.

WI05 15 min 2:38 MATRIX-ISOLATION SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBON (PAH) IONS: HYDROGENATED-PAH CATIONS AND THE PENTACENE IONS THOMAS M. HALASINSKI, FARID SALAMA, LOUIS J. ALLAMANDOLA, NASA Ames Research Center, Mail Stop: 245-6, Moffett Field, CA 94035-1000; and THOMAS BALLY, Institute of Physical Chemistry, University of Fribourg, Perolles, CH-1700 Fribourg, Switzerland.

WI06 SPECTROSCOPY AND RELAXATION KINETICS OF MATRIX ISOLATED CH/D RADICALS

15 min

2:55

AMY BURROUGHS and MICHAEL C. HEAVEN, Department of Chemistry, Emory University, Atlanta, GA 30322.

46

WI07 15 min 3:12 INVESTIGATION OF lATTICE DYNAMICS AND SYMMETRY OF HYDROGEN-CONTAINING IODATE CRYSTALS BY IR AND NQR METHODS A. BARABASH, Institute of Physics, National Academy of Sciences of Ukraine, 46, Prospect Nauki, 252022 Kiev, Ukraine.

Intermission WI08 NUCLEAR SPIN MODIFICATION OF METHANE IN PARAHYDROGEN CRYSTALS

15 min

3:45

MIZUHO FUSHITANI, MASAAKI MIKI, and TAKAMASA MOMOSE, Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, JAPAN. WI09 15 min 4:02 ANALYSIS OF FEMTOSECOND PUMP-PROBE SPECTRA IN THE CONDENSED PHASE: DYNAMICS AND POTENTIALS OF I2 IN RARE GAS MATRICES M. BARGHEER, K. DONOVANG, P. DIETRICH and N. SCHWENTNER, Institut fu¨ r Experimentalphysik, Freie Universit¨at Berlin, Arnimallee 14, 14195 Berlin, Germany. WI10 FOURIER TRANSFORM INFRARED SPECTRA OF Gen CLUSTERS TRAPPED IN SOLID Ar

10 min

4:19

S. DEVDAS,C.M.L. RITTBY, AND W.R.M. GRAHAM, Department of Physics and Astronomy, TCU, Fort Worth, TX 76129. WI11 FTIR AND DFT STUDIES OF GERMANIUM-CARBON CLUSTERS

15 min

4:31

D.L.ROBBINS,C.M.L. RITTBY, AND W.R.M. GRAHAM, Department of Physics and Astronomy, TCU, Fort Worth, TX 76129. WI12 15 min 4:48 SPECTROSCOPIC STUDY OF THE Ga(CH3 )3 PLUS HN3 REACTION SYSTEM IN LOW TEMPERATURE ARGON MATRICES JULANNA V. GILBERT, MATTHEW L. MULCH, Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208-2435. WI13 THERMOLUMINESCENCE OF IMPURITY-HELIUM SOLIDS IMMERSED IN LIQUID HELIUM

10 min

5:05

R. E. BOLTNEV, E. B. GORDON, V. V. KHMELENKO, I. N. KRUSHINSKAYA, M. V. MARTYNENKO, A. A. PELMENEV, E. A. POPOV, Institute of Energy Problems of Chemical Physics, 142432, Chernogolovka, Moscow Region, Russian Federation; A. F. SHESTAKOV, Institute of Problems of Chemical Physics, 142432, Chernogolovka, Moscow Region, Russian Federation.

47

WI14 ODMR OF ATOMS TRAPPED IN IMPURITY-HELIUM SOLID. a

10 min

5:17

E.A. POPOV, R.E. BOLTNEV, E.B. GORDON, A.A. PELMENEV, Institute of Energy Problems of Chemical Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow Region, Russia; Yu.A. DMITRIEV, A.F. Ioffe Physico-Technical Institute, St. Petersburg, 194021, Russia; A. WEIS, S. LANG, Institute of Applied Physics, Bonn University, 53115 Bonn, Germany. a Supported

by RFBR Projects 98-03-33095, 98-03-32283, 99-03-33261

48

RA. ELECTRONIC (SMALL) THURSDAY, JUNE 15, 2000 – 8:30 AM Room: 1153 SMITH LAB Chair: JEFF GRAY, Ohio Northern University, Ada, OH RA01

15 min

QUANTITATIVE ANALYSIS OF NON-ADIABATIC PREDISSOCIATION OF Li2 (F

8:30

1 + ) g

ROBERT J. LE ROY and GEOFFREY T. KRAEMER, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. RA02

15 min 1 + DIRECT-POTENTIAL-FIT DETERMINATION OF THE LiH (C  ) DOUBLE MINIMUM POTENTIAL

8:47

JENNING Y. SETO and ROBERT J. LE ROY, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. RA03

15 min

9:04 DIRECT-POTENTIAL-FIT DETERMINATION OF AN ACCURATE ANALYTICAL POTENTIAL FOR THE F (4) 1 + g

“SHELF” STATE OF Li2

YIYE HUANG and ROBERT J. LE ROY, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. RA04

10 min

OBSERVATION OF HIGH LYING LEVELS OF THE 1g

9:21

11 g STATE OF K2

A. J. ROSS, F. MARTIN and I. RUSSIER-ANTOINE, Laboratoire de Spectrom´etrie Ionique et Mol´eculaire (UMR 5579 CNRS), Bˆatiment 205, Universit´e Lyon I, Campus la Doua, 69622 Villeurbanne Cedex, France; H. M. CHEN, M. PICHLER, H. WANG and W. C. STWALLEY, Department of Physics, University of Connecticut, Storrs, CT 06269-3046, U.S.A. RA05 FOURIER TRANSFORM INFRARED EMISSION SPECTROSCOPY OF SeH

15 min

9:33

R. S. RAM, Department of Chemistry, University of Arizona, Tucson, AZ 85721; P. F. BERNATH, Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.

Intermission RA06 THE ELECTRONIC SPECTRA OF LaNH AND LaND

15 min

10:10

DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; ANTHONY J. MERER, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1; SCOTT J. RIXON, Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, Canada V6T 1Z1; THOMAS D. VARBERG, Department of Chemistry, Macalester College, St. Paul, MN 55105.

49

RA07 15 min 10:27 PHOTOFRAGMENTATION SPECTROSCOPY OF NIOBIUM CATION CLUSTERS IN A REFLECTRON TIME-OFFLIGHT (TOF) MASS SPECTROMETER AND DENSITY FUNCTIONAL CALCULATIONS ON NIOBIUM CATION CLUSTERS M. AYDIN, D. M. LINDSAY, J. R. LOMBARDI, Department of Chemistry and Center For Analysis of Structure and Interfaces (CASI), City College of New York of City University of New York 137th. Street and Convent Ave. New York, NY 10031. RA08

10 min

VIBRATIONAL STRUCTURE IN THE B4 

10:44

X 4  ELECTRONIC TRANSITION OF NbO

NING FANG, CHRISTOPHER T. KINGSTON, DAVID C.K. LIAO, ANTHONY J. MERER and SHUENNJIUN TANG, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1. RA09 ˜ 2 + , A ˜ 2 HIGH RESOLUTION STUDY OF THE B˜ 2 + X 14 15 14 TRIUM IMIDE (Y NH, Y NH, AND Y ND).

˜ 2 + , AND A ˜ 0 2 3=2 X

15 min 10:56 2 + ˜ X  SYSTEMS OF YT-

ZYGMUNT J. JAKUBEK AND BENOIT SIMARD, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6; HIDEAKI NIKI, Electrical and Electronics Engineering, Fukui University, Fukui-shi, Fukui 910, Japan; WALTER J. BALFOUR, Department of Chemistry, University of Victoria, Victoria, BC, Canada V8W 3V6. RA10 NEAR INFRARED LASER SPECTROSCOPY OF VS

15 min

11:13

QIN RAN, W. S. TAM, A. S-C. CHEUNG, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong; A. J. MERER, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B.C. V6T 1Z1, Canada. RA11 NEAR INFRARED LASER SPECTROSCOPY OF CrS

10 min

11:30

QIANG SHI, QIN RAN, W. S. TAM, J. W-H. LEUNG, A. S-C. CHEUNG, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong. RA12 15 min 11:42 AN AB INITIO MOLECULAR ORBITAL STUDY OF LOW LYING ELECTRONIC EXCITED STATES OF FeC SACHIKO S. ITONO, TETSUYA TAKETSUGU, TSUNEO HIRANO, Department of Chemistry, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan; UMPEI NAGASHIMA, National Institute for Advanced Interdisciplinary Research, Ibaraki 305-8562, Japan; K. AIUCHI, K. TSUJI, and K. SHIBUYA, Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, 152-8551, Japan.

50

RB. JET AND BEAM THURSDAY, JUNE 15, 2000 – 8:30 AM Room: 1009 SMITH LAB Chair: LAURI HALONEN, University of Helsinki, Helsinki, Finland RB01 15 min 8:30 HIGH-LYING RYDBERG STATES AND IONIZATION POTENTIAL OF VINYL CHLORIDE STUDIED BY TWOPHOTON RESONANT IONIZATION SPECTROSCOPY JIA-LIN CHANG, JAU-CHIN SHIEH, RUNHUA LI, JEN-CHIEH WU and YIT-TSONG CHEN, Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, and Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan. RB02 15 min 8:47 STRUCTURE AND MOLECULAR DYNAMICS OF THE HYDROGEN-BONDED PHENOL-METHANOL COMPLEX FROM HIGH RESOLUTION ELECTRONIC SPECTROSCOPY AND AB INITIO THEORY.a ¨ JOCHEN KUPPER, ARNIM WESTPHAL, MICHAEL SCHMITT and KARL KLEINERMANNS, HeinrichHeine-Universit¨at, Institut f¨ur Physikalische Chemie und Elektrochemie I, 40225 Du¨ sseldorf, Germany. a Work

supported by DFG.

RB03 THE HIGH RESOLUTION S1

15 min 9:04 S0 SPECTRUM OF THE ANISOLE-WATER COMPLEX: WATER AS AN ACID. a

JASON W. RIBBLETT, Department of Chemistry, Ball State University, Muncie IN 47302; DAVID R. BORST, and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. a Work

supported by NSF.

RB04 BENZONITRILE AND ITS WATER COMPLEX: THE S1

15 min 9:21 S0 SPECTRUM AT ROTATIONAL RESOLUTION. a

DAVID R. BORST and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. a Work

supported by NSF.

RB05 HIGH RESOLUTION SPECTRUM OF THE 1,2-DIMETHOXYBENZENE/D2 O COMPLEX a

15 min

9:38

JOHN YI and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. a Work

supported by NSF

RB06 15 min 9:55 A HIGH RESOLUTION ELECTRONIC SPECTRUM OF THE PARA-DIFLUOROBENZENE/WATER COMPLEX a CHEOLHWA KANG and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260. a work

supported by NSF

51

Intermission RB07 SPECTROSCOPY AND STRUCTURE OF A HYDROGEN BONDED CIS AMIDE DIMER

10 min

10:30

A. V. FEDOROV, J. R. CABLE, Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403. RB08 15 min 10:42 ELECTRONIC SPECTROSCOPY OF TWO N-PHENYL CIS AMIDES AND THEIR HYDROGEN BONDED CLUSTERS WITH WATER AND AMMONIA A. V. FEDOROV, J. R. CABLE, Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403; JOEL CARNEY, T. S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907. RB09 15 min 10:59 RESONANT ION-DIP INFRARED SPECTROSCOPY OF TWO N-PHENYL CIS AMIDES AND THEIR HYDROGEN BONDED CLUSTERS WITH WATER AND AMMONIA JOEL CARNEY, T. S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907; A. V. FEDOROV, J. R. CABLE, Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403. RB10 15 min 11:16 IR-PIRI AND IR-PHOTODISSOCIATION SPECTROSCOPY PERFORMED ON AROMATIC IONS AND HYDROGEN-BONDED CLUSTERS M. GERHARDS, C. UNTERBERG, A. JANSEN, K. KLEINERMANNS, H.-Heine Universit a¨ t D¨usseldorf, Institut f¨ur Physikalische Chemie I 40225 D¨usseldorf, Germany. RB11 15 min 11:33 THE INFRARED SPECTROSCOPY OF STRONGLY H-BONDED DIMERS: A NEW LOOK AT AN OLD PROBLEM GINA M. FLORIO, CHRISTOPHER J. GRUENLOH, and TIMOTHY S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393. RB12 THE 3m VIBRATION-TORSION-ROTATION ENERGY MANIFOLD OF METHANOL

15 min

11:50

LI-HONG XU, M. ABBOUTI TEMSAMANI, Department of Physical Sciences, University of New Brunswick, N.B. Canada E2L 4L5; X. WANG, Y. MA, A. CHIROKOLAVA, T. J. CRONIN, and D. S. PERRY, Department of Chemistry, University of Akron, Ohio 44325-3610.

52

RC. RADICALS AND IONS THURSDAY, JUNE 15, 2000 – 8:30 AM Room: 1000 McPHERSON LAB Chair: C. WELDON MATHEWS, The Ohio State University, Columbus, OH RC01 15 min 8:30 PHOTOIONIZATION OF HOCO RADICAL: A NEW UPPER LIMIT TO THE ADIABATIC IONIZATION ENERGY AND LOWER LIMIT TO THE ENTHALPY OF FORMATION BRANKO RUSCIC, MARITONI LITORJA, CHENGBIN XU and HAIRONG SHANG, Chemistry Division, Argonne National Laboratory, Argonne, IL 60439. RC02 15 min 8:47 ON THE CORRELATION BETWEEN PHOTOELECTRON ENERGY AND BENDING EXCITATION IN MOLECULAR PHOTOIONIZATION J. SCOTT MILLER, ERWIN D. POLIAKOFF, Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803. RC03

15 min 9:04 + + A THEORETICAL INVESTIGATION OF THE CLUSTER IONS Xe


HCO , Xe


HNN AND Xe


HNCH+ P. BOTSCHWINA, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany; H. STOLL, Institut f¨ur Theoretische Chemie, Universita¨ t Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany. RC04 THE FORMATION MECHANISMS OF D3 : AN INFRARED SPECTROSCOPIC INVESTIGATION

15 min

9:21

T. AMANO, Institute for Astrophysics and Planetary Sciences, Ibaraki University, Mito, Japan 310-8512; MAN-CHOR CHAN, Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong. RC05

15 min

9:38

1 SURVEY OF H+ 3 TRANSITIONS BETWEEN 3000 AND 4200 CM

C. MICHAEL LINDSAY, RONALD M. RADE and TAKESHI OKA, Department of Chemistry, Department of Astronomy and Astrophysics, and the Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637.

Intermission RC06

15 min

10:10

INFRARED SPECTRA OF H2 O+ -Arn COMPLEXES (n=1-14) OTTO DOPFER, DORIS ROTH, and ROUSLAN V. OLKHOV, Institut f¨ur Physikalische Chemie, Universita¨ t Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.

53

RC07

15 min

10:27

INFRARED SPECTRA OF NH3 + -Arn (n=1-6) COMPLEXES (n=1-6) OTTO DOPFER, NICOLA SOLCA, and ROUSLAN V. OLKHOV, Institut f¨ur Physikalische Chemie, Universit¨at Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland. RC08

15 min

10:44

THE ROTATIONAL SPECTRA OF THE HCCCNH+ , NCCNH+ , AND CH3 CNH+ IONS C. A. GOTTLIEB, A. J. APPONI, M. C. McCARTHY, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 and Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138; H. LINNARTZ, Institute for Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH 4056 Basel, Switzerland. RC09

15 min

11:01

MILLIMETER-WAVE TIME-RESOLVED STUDIES OF HCO+ - H2 INELASTIC COLLISIONS LEE C. OESTERLING, ERIC HERBST, and FRANK C. DE LUCIA, Department of Physics, The Ohio State University, 174 W. 18th Ave., Columbus, OH 43210. RC10 PURE ROTATIONAL SPECTRUM OF TiC` IN THE GROUND ELECTRONIC STATE

15 min

11:18

ATSUKO. MAEDA, Institute for Astrophysics and Planetary Sciences, Ibaraki University, Mito, Japan 3108512; TSUYOSHI HIRAO, PETER F. BERNATH, Centre of Molecular Beam and Laser Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada; and TAKAYOSHI AMANO, Institute for Astrophysics and Planetary Sciences, Ibaraki University, Mito, Japan 310-8512. RC11 Post-deadline Abstract FIRST EXPERIMENTAL OBSERVATIONS WITH CROSSED BEAMS FOR THE Sc + NO AND AB INITIO POTENTIAL ENERGY SURFACES

10 min

11:35

!ScO + N REACTION

G.-H. JEUNG, P. LUC, R. VETTER, Laboratoire Aim´e Cotton (NCRS UPR3321), Bˆat. 505, Campus d’Orsay, 91405 Orsay, France; D. W. KIM, K. S. KIM, Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, South Korea; H. S. LEE and Y. S. LEE, Department of Chemistry, Korea Advanced Institute of Science and Technology Taejon 305-701, South Korea. RC12 Post-deadline Abstract 10 min 11:47 FIRST EXPERIMENTAL OBSERVATIONS WITH CROSSED BEAMS FOR THE Ti + NO ! TiO + N AND Ti + O2 ! TiO + N REACTIONS AND AB INITIO POTENTIAL ENERGY SURFACES G.-H. JEUNG, P. LUC, R. VETTER, Laboratoire Aim´e Cotton (NCRS UPR3321), Bˆat. 505, Campus d’Orsay, 91405 Orsay, France; C. NAULIN, M. COSTES, Laboratoire de Physico-Chimie Mol´eculaire (CNRS UMR5803), Universit´e Bordeau I, 33405 Talence, France; K. H. KIM, Y. S. LEE, Department of Chemistry, Korea Advanced Institute of Science and Technology Taejon 305-701, South Korea; J. H. MOON, Y. H. KIM, Department of Ceramics, Korea Institute of Science and Technology, 130-650 Seoul, South Korea.

54

RD. VIBRONIC INTERACTIONS THURSDAY, JUNE 15, 2000 – 8:30 AM Room: 1015 McPHERSON LAB Chair: JON HOUGEN, NIST, Gaithersburg, MD RD01 Invited Talk EXPERIMENTAL MANIFESTATIONS OF THE JAHN-TELLER EFFECT

30 min

8:30

TIMOTHY A. BARCKHOLTZ, JILA, University of Colorado, Boulder, CO 80309-0440. RD02 15 min 9:05 CAS-SCF COMPUTATIONS ON JAHN-TELLER, RENNER-TELLER AND SECOND ORDER JAHN-TELLER SYSTEMS MICHAEL ROBB, MICHAEL J. BEARPARK, LUIS BLANCAFORT, Department of Chemistry, King’s College London, Strand, London WC2R 2LS, UK. RD03 15 min 9:22 AB INITIO CALCULATION OF THE SPECTROSCOPICALLY OBSERVABLE JAHN-TELLER CONSTANTS OF THE Xe 2 E001 STATE IN THE CYCLOPENTADIENYL RADICAL BRIAN E. APPLEGATE AND TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210; TIMOTHY A. BARCKHOLTZ, JILA, National Institute of Standards and Technology and The Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309. RD04

15 min

9:39

e 2 E00 STATE IN THE CYCLOPENTADIJAHN-TELLER ANALYSIS OF THE VIBRONIC STRUCTURE OF THE X 1 ENYL RADICAL

BRIAN E. APPLEGATE, ANDREW J. BEZANT, AND TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210; TIMOTHY A.BARCKHOLTZ, JILA, National Institute of Standards and Technology and The Department of Chemistry and Biochemistry, University of Colorado Boulder, Colorado 80309.

Intermission RD05 JAHN-TELLER AND PSEUDO JAHN-TELLER INTERACTIONS IN METAL TRIMERS

15 min

10:15

WOLFGANG E. ERNST, Departments of Physics and Chemistry, Penn State University, 104 Davey Laboratory, University Park, PA 16802. RD06 15 min 10:32 TENSORIAL DEVELOPMENT FOR THE ROVIBRONIC HAMILTONIAN AND TRANSITION MOMENTS OF OCTAHEDRAL XY6 MOLECULES IN A FOURFOLD DEGENERATE ELECTRONIC STATE ¨ V. BOUDON, M. REY, M. LOETE, F. MICHELOT, Laboratoire de Physique de l’Universit´e de Bourgogne, UMR CNRS 5027, 9 Av. A. Savary, BP 4780, F-21078 DIJON Cedex, FRANCE.

55

RD07 QUASI-JAHN-TELLER EFFECT IN CHEMICAL REACTIONS

15 min

10:49

LICHANG WANG , Department of Chemistry, The Ohio State University, Columbus, OH 43210. RD08

15 min 11:06 2 RENNER-TELLER EFFECTS IN THE i GROUND STATES OF THE SiCH/SiCD and GeCH/GeCD RADICALS HAIYANG LI, TONY C. SMITH, DAVID A. HOSTUTLER, DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; ANTHONY J. MERER, Chemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1.

56

RE. MICROWAVE THURSDAY, JUNE 15, 2000 – 1:30 PM Room: 1153 SMITH LAB Chair: HELEN LEUNG, Mount Holyoke College, South Hadley, MA RE01 15 min THE ROTATIONAL SPECTRA AND STRUCTURES OF TWO ISOMERS OF THE HCCH-OCS DIMER

1:30

SEAN A. PEEBLES and ROBERT L. KUCZKOWSKI, Department of Chemistry, University of Michigan, 930 North University Ave., Ann Arbor, MI 48109-1055 USA. RE02 15 min THE ROTATIONAL SPECTRA AND STRUCTURES OF THE HCCH-(OCS)2 and OCS-(HCCH)2 TRIMERS

1:47

SEAN A. PEEBLES and ROBERT L. KUCZKOWSKI, Department of Chemistry, University of Michigan, 930 North University Ave., Ann Arbor, MI 48109-1055 USA. RE03 15 min 2:04 ISOMERS IN HELIUM COMPLEXES: OBSERVATION OF T-SHAPED AND LINEAR He-CH3 F, AND PREDICTION OF TWO NEARLY ISOENERGETIC FORMS OF He-ClF3 KELLY J. HIGGINS, and WILLIAM KLEMPERER, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138. RE04 15 min 2:21 MICROWAVE INVESTIGATIONS OF C5 H5 N-SO3 AND HCCCN-SO3 : THE PRINCIPLE OF HARD AND SOFT ACIDS AND BASES APPLIED TO PARTIALLY BONDED SYSTEMS S. W. HUNT, D. L. FIACCO, M. CRADDOCK, and K. R. LEOPOLD , Department of Chemistry, University of Minnesota, Minneapolis, MN 55455. RE05 MICROWAVE ROTATIONAL SPECTRUM OF THE Kr-CH4 VAN DER WAALS COMPLEX

15 min

2:38

¨ YAQIAN LIU and WOLFGANG JAGER, Department of Chemistry, University of Alberta, Edmonton, AB, Canada, T6G 2G2. RE06 15 min THE MICROWAVE SPECTRA OF THE FLUOROBENZENE-KRYPTON VAN DER WAALS COMPLEX ¨ KAI BRENDEL and HEINRICH MADER, Institut f¨ur Physikalische Chemie, Olshausenstr. 40, D-24098 Kiel, Germany.

2:55

Universita¨ t Kiel,

RE07 10 min 3:12 A COMPLETE STRUCTURE FOR THE GAUCHE ROTAMER OF 1,1,2,2-TETRAFLUOROETHANE FROM MICROWAVE SPECTROSCOPY ´ MATE, ´ ANNORMAN C. CRAIG, Department of Chemistry, Oberlin College, Oberlin, OH 44074; BEL EN GELA HIGHT WALKER, and RICHARD D. SUENRAM, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899.

57

RE08 15 min 3:24 PSEUDO-re STRUCTURES FROM EXPERIMENTAL ROTATIONAL CONSTANTS AND AB INIT IO VIBRATION-ROTATION CONSTANTS P. GRONER, and R. D. WARREN, Department of Chemistry, University of Missouri - Kansas City, Kansas City, MO 64110.

Intermission RE09 15 min 4:00 PHYSICAL INTERPRETATION OF TORSION-ROTATIONAL PARAMETERS IN METHANOL AND ITS ISOTOPOMERS: COMPARISON OF GLOBAL FIT AND CENTRIFUGAL CALCULATION RESULTS YUN-BO DUAN and ANNE B. MCCOY, Department of Chemistry, The Ohio State University, Columbus, OH 43210. RE10 10 min 4:17 CALCULATION OF MOLECULAR PARAMETERS FOR ISOTOPOMERS OF CD3 OH SPECIES OF METHANOL LI WANG, AND KOJIRO TAKAGI, Department of Physics, Toyama University, Toyama 930-8555, Japan. RE11 THE GROUND STATE ROTATIONAL SPECTRUM OF CH2 DOH

15 min

4:29

J. C. PEARSON, B. J. DROUIN AND H. M. PICKETT, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109. RE12 THE ROTATIONAL SPECTRUM OF DEUTERATED ISOPROPANOL (CH3 )2 CHOD

15 min

4:46

EIZI HIROTA, The Graduate University for Advanced Studies, Hayama, Kanagawa 240-0193, JAPAN ; YOSHIYUKI KAWASHIMA, Department of Applied Chemistry, Kanagawa Institute of Technology, Atsugi, Kanagawa 243-0292, JAPAN. RE13 15 min 5:03 THE ROTATIONAL/CONCERTED TORSIONAL SPECTRUM OF THE g’Gg-CONFORMER OF ETHYLENE GLYCOL DINES CHRISTEN, Institute of Physical and Theoretical Chemistry, University of T¨ubingen, Germany; LAURENT COUDERT, Laboratoire de Photophysique Mol´eculaire, CNRS, Universit´e de Paris-Sud, France; RICK D. SUENRAM and A. HIGHT WALKER, Molecular Physics Division, NIST, Gaithersburg, MD, USA; A. LARSON and DIETER CREMER, Teoretisk Kemi, G¨oteborg, Sweden. RE14 THE SUBMILLIMETER-WAVE SPECTRUM OF ALLYL ALCOHOL (CH2 =CHCH2 OH)

10 min

5:20

BRIAN J. DROUIN, JOHN C. PEARSON, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099. RE15 15 min 5:32 THE ROTATIONAL-TORSIONAL SPECTRUM OF METHYL FORMATE:PRECISE MEASUREMENTS ON AND INTERPRETATION OF MILLIMETRIC WAVE TRANSITIONS H.NADGARAN, Physics Department, Shiraz University, Shiraz 71454, Iran..

58

RF. METAL CLUSTERS THURSDAY, JUNE 15, 2000 – 1:30 PM Room: 1009 SMITH LAB Chair: MICHAEL DUNCAN, University of Georgia, Athens, GA RF01 Invited Talk ELECTRONIC SPECTROSCOPY OF ALUMINUM ATOM-MOLECULE COMPLEXES

30 min

1:30

PAUL J. DAGDIGIAN, Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218. RF02 ZEKE-PFI SPECTROSCOPY OF THE Al-(H2 O) AND Al-(D2 O) COMPLEXES.

15 min

2:05

J.K. AGREITER, A.M. KNIGHT, G.A. GRIEVES, M.A. DUNCAN, Department of Chemistry, University of Georgia, Athens, GA 30602, USA. RF03 EXPERIMENTAL AND THEORETICAL STUDY OF THE BOUND-FREE G2 (4p)

15 min 2:22 2 X (3p) TRANSITION OF

AlAr JAMES M. SPOTTS, CHI-KIN WONG, MATTHEW S. JOHNSON, MITCHIO OKUMURA, A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125; JEFFREY I. SHEEHY and PETER. W. LANGHOFF, Air Force Research Laboratory, OLAC PL/RKS, Edwards Air Force Base, CA 93524. RF04

10 min

2:39

PHOTODISSOCIATION SPECTROSCOPY OF THE Ca+ -Ar2 COMPLEX J. E. REDDIC, J. VELASQUEZ, K. N. KIRSCHNER, M. A. DUNCAN, Department of Chemistry, University of Georgia, Athens, GA 30602, USA.

Intermission RF05 OPTICAL STARK SPECTROSCOPY OF YTTRIUM DICARBIDE,YCC

15 min

3:10

ALEXANDRA JANCZYK and TIMOTHY C. STEIMLE, Department of Chemistry and Biochemistry, Arizona State University, Tempe, Az, 85287-1604. RF06

15 min

˜ 2 (0; 0; 0) OPTICAL STARK MEASUREMENT FOR THE A

3:27

X2 + (0,0,0) OF MgNC

ROBERT R. BOUSQUET and TIMOTHY C. STEIMLE, Department of Chemistry and Biochemistry, Arizona State University, Tempe, Az, 85287-1604.

59

RF07 LASER INDUCED FLUORESCENCE SPECTROSCOPY OF JET-COOLED MgOH

15 min

3:44

MASARU FUKUSHIMA and TAKASHI ISHIWATA, Department of Information Sciences, Hiroshima City University, Asa-Minami, Hiroshima 731-3194, Japan. RF08 RESONANT TWO PHOTON MPI SPECTROSCOPY OF Ca2 Cl3

15 min

4:01

J. D. LOBO, A. DEEV, C. K. WONG, M. OKUMURA, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125. RF09 15 min 4:18 DIMERS OF ALKALINE EARTH METAL HALIDE RADICALS, (MX)2 (M = Be, Mg, Ca; X = F, Cl): A THEORETICAL STUDY G.P. LI and I.P. HAMILTON, Department of Chemistry, Wilfrid Laurier University, Waterloo, Canada N2L 3C5. RF10 THE VIBRATIONAL SPECTRA OF TRANSITION METAL MONOCARBONYLS MOLECULES

15 min

4:35

B. TREMBLAY, L. MANCERON, and M.E. ALIKHANI, L.A.D.I.R./Spectrochimie Moleculaire, U.M.R. 7075, CNRS-Universite Pierre et Marie Curie, Boite 49, 4 Place Jussieu, 75252 Paris, Cedex 05, France.

60

RG. INFRARED THURSDAY, JUNE 15, 2000 – 1:30 PM Room: 1000 McPHERSON LAB Chair: NASSER MOAZZEN-AHMADI, University of Calgary, Calgary, Canada

RG01 15 min RITZ ASSIGNMENT AND AWAT ANALYSIS OF THE RING-PUCKERING HOT BANDS OF OXETANE

1:30

GIOVANNI MORUZZI, Dipartimento di Fisica dell’Universit`a di Pisa and INFM, Via Filippo Buonarroti 2, I-56127 Pisa, Italy; MARC KUNZMANN, Institut f¨ur Physikalische Chemie der Georg-August-Universita¨ t G¨ottingen, Germany; BRENDA P. WINNEWISSER AND MANFRED WINNEWISSER, PhysikalischChemisches Institut, Justus-Liebig-Universit¨at, Heinrich-Buff-Ring 58, D-35392 Gießen, Germany.

RG02 15 min 1:47 ANALYSIS OF THE ROTATIONAL STRUCTURE IN TWO BANDS OF THE ANTI ROTAMERS OF 1,1,2,2TETRAFLUOROETHANE AND ITS d2 ISOTOPOMER IN HIGH-RESOLUTION INFRARED SPECTRA NORMAN C. CRAIG, CATHERINE M. OERTEL and DAVID C. OERTEL, Department of Chemistry, Oberlin College, Oberlin, OH 44074; MICHAEL LOCK, Physikalisch-Chemisches Institut, Justus Liebig Universit¨at, D-35392 Giessen, Germany.

RG03 15 min 2:04 VIBRATIONAL POTENTIAL ENERGY SURFACES FOR THE RING-PUCKERING AND RING-FLAPPING VIBRATIONS OF 1,3-BENZODIOXOLE IN ITS S0 AND S1 ( ,   ) ELECTRONIC STATES J. LAANE, K. MORRIS, S. SAKURAI, E. BONDOC, Department of Chemistry, Texas A&M University, College Station, TX 77842-3012; N. MEINANDER, Department of Physics, University of Helsinki, Helsinki, Finland.

RG04 10 min 2:21 CONFORMATIONAL STABILITY FROM TEMPERATURE DEPENDENT FT-IR SPECTRA OF LIQUID RARE GAS SOLUTIONS AND AB INITIO CALCULATIONS FOR 1-PENTYNE BARRY R. DREW AND J. R. DURIG, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499.

RG05 CONTINUING RESEARCH INTO THE OVERTONE SPECTRA OF TRIMETHYL AMINE

15 min

2:33

BRANT BILLINGHURST, KATHLEEN GOUGH, Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada; HENRIK G. KJAERGAARD AND GEOFF LOW, Department of Chemistry, University of Otago, Dunedin, New Zealand.

Intermission

61

RG06 LARGE TORSIONAL EFFECTS IN THE PARALLEL BAND (v5

15 min

=1

3:15

0) OF CH3 SiF3

S. -X. WANG, Department of Physics and Astronomy, University of British Columbia, Vancouver, B. C., Canada, V6T 1Z1; J. SCHRODERUS, Department of Physical Sciences, University of Oulu, P.O. Box 3000, Oulu, Finland, FIN 90401 ; I. OZIER , Department of Physics and Astronomy, University of British Columbia, Vancouver, B. C., Canada, V6T 1Z1; and V.-M. HORNEMAN, Department of Physical Sciences, University of Oulu, P.O. Box 3000, Oulu, Finland, FIN 90401.

RG07 10 min 3:32 RAMAN AND INFRARED SPECTRA, CONFORMATIONAL STABILITY, AB INITIO CALCULATIONS AND VIBRATIONAL ASSIGNMENTS FOR ETHYL FLUOROSILANE GAMIL A. GUIRGIS, YASSER E. NASHED, JING TAO AND JAMES R. DURIG, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499.

RG08 15 min 3:44 RAMAN AND INFRARED SPECTRA, CONFORMATIONAL STABILITY, BARRIERS TO INTERNAL ROTATION, AB INITIO CALCULATIONS AND ro STRUCTURE FOR VINYL SILYL FLUORIDE YASSER NASHED, GAMIL A. GUIRGIS, M. A. QTAITAT AND J. R. DURIG, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499.

RG09 10 min 4:01 CONFORMATIONAL ANALYSIS, BARRIERS TO INTERNAL ROTATION AND AB INITIO CALCULATIONS OF 3-FLUORO-1-BUTENE SEUNG WON HUR, TODOR K. GOUNEV, GAMIL A. GUIRGIS AND JAMES R. DURIG, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499.

RG10 15 min 4:13 VIBRATIONAL DEPENDENCE OF THE TORSIONAL BARRIER HEIGHT AND THE A/B INTENSITY EVOLUTION IN THE OH OVERTONE SPECTRA OF METHANOL M. ABBOUTI TEMSAMANI, LI-HONG XU, Department of Physical Sciences, University of New Brunswick, N.B. Canada E2L 4L5; D. S. PERRY, Department of Chemistry, University of Akron, Ohio 443253610.

RG11 15 min 4:30 FOURIER TRANSFORM SPECTRA AND INVERTED TORSIONAL STRUCTURE FOR A CH3 -BENDING FUNDAMENTAL OF CH3 OH R.M. LEES, LI-HONG XU and ANNA K. KRISTOFFERSON, Department of Physical Sciences, University of New Brunswick, Saint John, NB, Canada E2L 4L5; MICHAEL LOCK and B.P. WINNEWISSER, Physikalisch-Chemisches Institut, Justus Liebig University, D-35392 Giessen, Germany; J.W.C. JOHNS, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6.

62

RG12 15 min 4:47 HIGH RESOLUTION FOURIER TRANSFORM FAR-INFRARED SPECTROSCOPY OF CH3 OD: GLOBAL FIT OF TORSION-ROTATIONAL TRANSITIONS IN THE FIRST THREE TORSIONAL STATES INDRANATH MUKHOPADHYAY, Laser Programme, Centre for Advanced Technology, Indore 452 013, India; XIAN-XIAO HAO, Department of Physics, Yantai Normal University, Yantai, Shandong 264000, China; GEORG CHR. MELLAU and STEFAN KLEE, Physikalisch Chemisches Institut der Justus-LiebigUniversitt, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany; YUN-BO DUAN and ANNE B. MCCOY, Department of Chemistry, The Ohio State University, Columbus, OH 43210. RG13 15 min 5:04 ABOUT NATURE OF NONCOINCIDENCE FOR FREQUEHCY AND LINE WIDTH OF STOKES AND ANTISTOKES COMPONENTS IN RAMAN SPECTRA E. N. SHERMATOV, Samarkand State University, Univ. bulv 15, 703004 Samarkand, Uzbekistan. RG14 STRUCTURE OF LIQUIDS AND LOW-FREQUENCY RAMAN EFFECT

15 min

5:21

E. N. SHERMATOV, U.N. RADJABOV, Samarkand State University, Univ. bulv 15, 703004 Samarkand, Uzbekistan.

63

RH. THEORY THURSDAY, JUNE 15, 2000 – 1:30 PM Room: 1015 McPHERSON LAB Chair: PHILLIP CHRISTIANSEN, Clarkson University, Potsdam, NY RH01 Invited Talk 30 min 1:30 THE ROLE OF CONICAL INTERSECTIONS IN PHOTOCHEMISTRY,ELECTRONIC ENERGY TRANSFER AND ELECTRON TRANSFER MICHAEL ROBB, MICHAEL J. BEARPARK, FRANCK JOLIBOIS, ADELAIDA SANCHEZ-GALVEZ, PATRICIA HUNT, Department of Chemistry, King’s College London, Strand, London WC2R 2LS, UK; MASSIMO OLIVUCCI, Istituto di Chimica Organica, Universit´a degli Studi di Siena, Via Aldo Moro, I-53100 Siena, Italy; FERNANDO BERNARDI, MARCO GARAVELLI, Dipartimento di Chimica“G. Ciamician”, Universit`a di Bologna, Via Selmi 2, 40126 Bologna, Italy. RH02 ELECTRONIC STATES OF ACTINYL IONS

15 min

2:05

R. M. PITZER, J.-P. BLAUDEAU, S. R. BROZELL, S. MATSIKA, Z. ZHANG, Department of Chemistry, Ohio State University, Columbus, OH 43210. RH03 THE ELECTRONIC SPECTRA OF THE AMERICYL AND CURYL IONS

15 min

2:22

SCOTT R. BROZELL and RUSSELL M. PITZER, Department of Chemistry, The Ohio State University, Columbus, OH 43210. RH04 THE ELECTRONIC STRUCTURE OF THE PLUTONYL ION

15 min

2:39

JEAN-PHILIPPE BLAUDEAU, (Present Address: ASC/MSRC 2435 5th St. B676, Wright-Patterson AFB, Ohio, 45433); BRUCE E. BURSTEN, and RUSSELL M. PITZER, Department of Chemistry, The Ohio State University, Columbus, OH 43210. RH05 SPECIATION OF THE PLUTONYL FORMS OF PLUTONIUM

15 min

2:56

JEAN-PHILIPPE BLAUDEAU, (Present Address: ASC/MSRC 2435 5th St. B676, Wright-Patterson AFB, Ohio, 45433); BRUCE E. BURSTEN, Department of Chemistry, The Ohio State University, Columbus, OH 43210.

Intermission RH06 10 min 3:30 THE IONIZATION ENERGY OF THE DIAZOMETHYL (HCNN) AND CYANAMIDYL (HNCN) RADICALS PATRICK E. FLEMING, Department of Chemistry, Santa Clara University, Santa Clara, CA 95053..

64

RH07 15 min 3:42 THEORETICAL PREDICTION OF THE SPECTROSCOPIC CONSTANTS OF FeS: AN AB INITIO MOLECULAR ORBITAL STUDY SACHIKO S. ITONO, YUKARI MITSUI, TETSUYA TAKETSUGU, TSUNEO HIRANO, Department of Chemistry, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan; UMPEI NAGASHIMA, National Institute for Advanced Interdisciplinary Research, Ibaraki 305-8562, Japan. RH08 DFT TEST STUDY ON VAN DER WAALS DIMERS

10 min

3:59

A. J. HERNANDEZ, M. C. SALAZAR, Department of Chemistry, Simon Bolivar University, Caracas 1080A, Venezuela; C. E. MANZANARES, Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76798. RH09 10 min AB INITIO TEST STUDY ON THE VERTICAL EXCITATION ENERGY OF VAN DER WAALS DIMERS

4:11

M. C. SALAZAR, A. J. HERNANDEZ, Department of Chemistry, Simon Bolivar University, Caracas 1080A, Venezuela; C. E. MANZANARES, Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76798. RH10

15 min

4:23

INTENSITIES OF THE ELECTRONIC SPECTRUM OF NpO+ 2 SPIRIDOULA MATSIKA, RUSSELL M. PITZER, Department of Chemistry, The Ohio State University, 100 W.18th Avenue, Columbus, OH, 43210. RH11 STRUCTURE AND SPECTRA OF UO2 F2

15 min

4:40

QI WANG and R.M. PITZER, Department of Chemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, OH, 43210. RH12 FREQUENCY ANALYSIS OF BINARY MIXTURES INVOLVING HYDROGEN BONDS

15 min

4:57

N. SATHYAN, J. SOBHANADRI and V. SANTHANAM, DEPARTMENT OF PHYSICS, PRESIDENCY COLLEGE, CHENNAI - 600 005, INDIA.

65

FA. JET AND BEAM FRIDAY, JUNE 16, 2000 – 8:30 AM Room: 1153 SMITH LAB Chair: JOHN HEPBURN, University of Waterloo, Waterloo, Canada FA01 IR-REMPI DOUBLE RESONANCE SPECTROSCOPY OF NO-Ar AND NO-Ne COMPLEXES

15 min

8:30

YANGSOO KIM, J. FLENIKEN, and H. MEYER, Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602; M. H. ALEXANDER, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742-2021; and P. J. DAGDIGIAN, Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218-2685. FA02 HIGH RESOLUTION LIF SPECTROSCOPY OF THE Ar.NO COMPLEX

15 min

8:47

` TIMOTHY G. WRIGHT, JEROME LOZEILLE, School of Chemistry, Physics and Environmental Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, U. K.; CHRISTOPHER C. CARTER and TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, Columbus, OH 43210. FA03

15 min

9:04

˜ STATE (1 + 1) REMPI SPECTROSCOPY OF NO.N2 and NO.CO VIA THE A ` TIMOTHY G. WRIGHT, SOPHIA E. DAIRE, JEROME LOZEILLE, STUART D. GAMBLIN, School of Chemistry, Physics and Environmental Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, U. K.. FA04 THRESHOLD ION-PAIR PRODUCTION SPECTROSCOPY (TIPPS) of H2 and D2

15 min

9:21

X. K. HU, R. C. SHIELL, Q. J. HU and J. W. HEPBURN, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. FA05 15 min 9:38 HS-H BOND DISSOCIATION ENERGY DETERMINATION BY THRESHOLD ION-PAIR PRODUCTION SPECTROSCOPY (TIPPS) X. K. HU, R. C. SHIELL, Q. J. HU and J. W. HEPBURN, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada.

Intermission FA06 THE REMPI STUDY OF BH IN THE RANGE OF 368-370NM

15 min

10:10

JASON CLARK, EDWARD R. GRANT, Dept. of Chemistry, Purdue University, West Lafayette, IN, USA 47907; LIMIN ZHANG, Open Laboratory of Bond-Selective Chemistry, University of Science and Technology of China , Hefei, Anhui, P.R. China 230026.

66

FA07 15 min 10:27 RESONANCE ENHANCED TWO-PHOTON IONIZATION (RE2PI) SPECTRUM OF THE 520 NM SYSTEM OF RbCs YOUNGJEE YOON, YONGHOON LEE, SUN JONG BAEK, JEONGYE CHOI, and BONGSOO KIM, Department of Chemistry, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea. FA08 PREDISSOCIATION DYNAMICS OF THE T-SHAPED AND LINEAR ISOMERS OF I2 (B)Ar

15 min

10:44

AMY BURROUGHS and MICHAEL C. HEAVEN, Department of Chemistry, Emory University, Atlanta, GA 30322. FA09 ON THE HYPERFINE STRUCTURE OF NO2 LEVELS NEAR DISSOCIATION THRESHOLD

10 min

11:01

JU XIN AND SCOTT A. REID, Department of Chemistry, Marquette University, Milwaukee, WI 53201-1881. FA10 Post-deadline Abstract 15 min 11:13 MILLIMETER WAVE JET SPECTROSCOPY OF CARBON MONOXIDE-CONTAINING VAN DER WAALS COMPLEXES KALEY A. WALKER and A. R. W. MCKELLAR, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada.

67

FB. THEORY FRIDAY, JUNE 16, 2000 – 8:30 AM Room: 1009 SMITH LAB Chair: JEAN BLAUDEAU, The Ohio State University, Columbus, OH

FB01 10 min 8:30 INTERACTIVE COMPUTER PROGRAM FOR COMPUTER-ASSISTED ASSIGNMENT OF MOLECULAR SPECTRAa MITCHELL STEPHEN E. and JOHN W. FARLEY, Department of Physics, University of Nevada, Las Vegas, NV, 89154. a Supported

by DOE/EPSCoR

FB02 BASIS SETS IN CORRELATED EFFECTIVE POTENTIAL CALCULATIONS

15 min

8:42

P. A. CHRISTIANSEN, Department of Chemistry, Clarkson University, Potsdam, New York 13699-5810.

FB03

15 min

8:59 + A FIRST PRINCIPLE EFFECTIVE HAMILTONIAN FOR INCLUDING NON-ADIABATIC EFFECTS FOR H2 AND HD+ DAVID W. SCHWENKE, Mail Stop 230-3, NASA Ames Research Center, Moffett Field, CA 94035-1000.

FB04

15 min

9:16

THE FORBIDDEN ROTATION AND ROTATION-VIBRATION SPECTRUM OF H+ 2 P. R. BUNKER, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada; R. E. MOSS, Department of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K.. FB05

15 min 9:33 + CALCULATIONS OF THE H3 ROVIBRATIONAL SPECTRUM TO LEVELS NEAR THE BARRIER TO LINEARITY JAMES K. G. WATSON, Steacie Institute for Molecular Sciences, National Research Council, Ottawa, Ontario, Canada K1A OR6. FB06 15 min 9:50 ELECTRONIC STRUCTURES AND OPTICAL PROPERTIES OF OPEN AND CAPPED CARBON NANOTUBES W. Z. LIANG, S. YOKOJIMA, and G. H. CHEN, Department of Chemistry, The University of Hong Kong,Pokfulam Road, Hong Kong.

Intermission

68

FB07 METHODS OF SCALING QUANTUM MECHANICAL MOLECULAR FORCE FIELDS

10 min

10:30

YURII N. PANCHENKO, Laboratory of Molecular Spectroscopy, Division of Physical Chemistry, Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Vorobiovy gory, Russian Federation, C. I. S. FB08 10 min TRANSFERABILITY OF SCALE FACTORS VERSUS TRANSFERABILITY OF FORCE CONSTANTS

10:42

YURII N. PANCHENKO, Laboratory of Molecular Spectroscopy, Division of Physical Chemistry, Department of Chemistry, M. V. Lomonosov Moscow State University, Vorobiovy gory, Moscow 119899, Russian Federation, C. I. S. FB09 Post-deadline Abstract 15 min 10:54 UNDULATING POTENTIAL ENERGY SURFACES FOR THE RYDBERG STATES OF SMALL MOLECULES CONTAINING A METAL ATOM N. GEUM, Department of Chemistry, Dankook University, Cheonan, 330-714, South Korea; G.-H. JEUNG, Laboratoire Aim´e Cotton (CNRS UPR3321) and ASCI (CNRS UPR9029, Bˆat. 505-506, Campus d’Orsay, 91405 Orsay, France. FB10 Post-deadline Abstract 15 min 11:11 THE STUDY OF THE MULTIPHOTONIC EXCITES FOR THE DIATOMIC MOLECULAR DISSOCIATION AND THE QUANTUM FLUCTUATIONS THEORY SILVESTRU POPESCU and STEFAN CARCU, Research Institute for Electrical Engineering - ICPE Bistrita Subsidiary Str. Parcului, No. 7, Bistrita Ro - 4400 Romania.

69

FC. RADICALS AND IONS FRIDAY, JUNE 16, 2000 – 8:30 AM Room: 1000 McPHERSON Chair: PATRICK FLEMING, Santa Clara University, Santa Clara, CA FC01

15 min

8:30

THE HIGH RESOLUTION INFRARED SPECTRUM OF N2 -H+ -N2 D. VERDES, H. LINNARTZ, J.P. MAIER, Department of Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH 4056 Basel, Switzerland; P. BOTSCHWINA, R. OSWALD, Institut f u¨ r Physikalische Chemie, Tammannstrasse 6, D 37077 Go¨ ttingen, Germany; P. ROSMUS, Theoretical Chemistry Group, Universit´e de Marne-la-Vall´ee, F 77454 Champs sur Marne, France; P.J. KNOWLES, School of Chemistry, University of Birmingham, Birmingham, B15 2TT, UK. FC02 CAVITY RING DOWN SPECTROSCOPY OF CARBON CHAIN RADICALS

15 min

8:47

H. LINNARTZ, T. MOTYLEWSKI, O. VAIZERT, and J.P. MAIER, Department of Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH 4056 Basel, Switzerland. FC03 10 min 9:04 FAR INFRARED LMR SPECTROSCOPIC MEASUREMENTS OF THE QUASI-LINEAR MOLECULE DCCN W. E. JONES, School of Physical Sciences, University of Windsor, ON, N9E3G5, Canada; F. SUN and R. F. CURL, Rice University, Department of Chemistry and Rice Quantum Institute, Houston, TX 77005; M. D. ALLEN and K. M. EVENSON, National Institute of Standards and Technology, Time and Frequency Division 847, Boulder, CO 80303; J. M. BROWN, Physical and Theoretical Chemistry Laboratory, Oxford University, Oxford OX1 3QZ, United Kingdom. FC04 15 min HIGH-RESOLUTION SPECTROSCOPIC STUDIES OF THE 5 BENDING FUNDAMENTAL OF HCCN

9:16

M. D. ALLEN, K. M. EVENSON, Time and Frequency Division, National Institute of Standards and Technology, Boulder, CO 80303-3328; and J. M. BROWN, The Physical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom.

Intermission FC05 Post-deadline Abstract 15 min 9:50 HIGH-RESOLUTION INFRARED SPECTROSCOPY OF H2 IN ION CLUSTERS PRODUCED BY -RAY IRRADIATION OF PARAHYDROGEN CRYSTALS TAKAMASA MOMOSE, Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 6068502, Japan; C. MICHAEL LINDSAY, YU ZHANG, and TAKESHI OKA, Department of Chemistry, Department of Astronomy and Astrophysics, and the Enrico-Fermi Institute, The University of Chicago, Chicago IL, 60637, USA.

70

FC06 Post-deadline Abstract 15 min 10:07 OBSERVATION AND ANALYSIS IR ABSORPTION SPECTRA OF MIXTURES HF AND HCL WITH CO2 A. KARIMOV, M. KULIEVA and K. KHUDOINAZAROV, Samarkand State University, Samarkand 703004, Uzbekistan. FC07 Post-deadline Abstract 15 min 10:24 INFRARED SPECTRA OF HYDROGENATED AMORPHOUS CARBON (HAC) AND PARTIALLY HYDROGENATED FULLERENES (PHFs) K. TERESZCHUK, V. GRICHKO, W. W. DULEY, P. F. BERNATH, Departments of Chemistry and Physics, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1. FC08 Post-deadline Abstract 15 min 10:41 THE TEMPERATURE DEPENDENCE OF THE RAMAN BANDWIDTHS FOR THE HARD MODES OF THE AMMONIUM HALIDES CLOSE TO PHASE TRANSITIONS H. YURTSEVEN, Department of Physics, Istanbul Technical University, Maslak, Istanbul, Turkey.

71

FD. METAL CLUSTERS FRIDAY, JUNE 16, 2000 – 8:30 AM Room: 1015 McPHERSON LAB Chair: PAUL DAGDIGIAN, The Johns Hopkins University, Baltimore, MD FD01 IR SPECTROSCOPY OF GAS PHASE METAL CLUSTERS

30 min

8:30

GERT VON HELDEN, DENIZ VAN HEIJNSBERGEN, GERARD MEIJER, FOM Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3430 BE Nieuwegein, The Netherlands, http://www.rijnh.nl; MICHAEL A. DUNCAN, Department of Chemistry, University of Georgia, Athens, Georgia 30602, U.S.A., http://www.chem.uga.edu. FD02 15 min 9:05 THE INSULATOR TO METAL TRANSITION IN DIVALENT METAL CLUSTERS: A NEGATIVE ION PHOTOELECTRON SPECTROSCOPY STUDY OWEN C. THOMAS, WEIJUN ZHENG SHOUJUN XU, and KIT H. BOWEN, Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218. FD03 15 min 9:22 REACTIVITY OF YTTRIUM CLUSTERS WITH AMMONIA AND IONIZATION POTENTIALS OF YTTRIUM NITRIDE CLUSTERS. E. BENICHOU, E. LANGLOIS and B. SIMARD, Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada; A. MARTINEZ, Departamento de Quimica, Division de Ciencias Basicas e Ingeniera, Universidad Autonoma Metropolitana - Iztapala, A.P. 55-534,Mexico, 09340 Mexico. FD04 ZEKE-PFI SPECTROSCOPY AND THEORETICAL CALCUATIONS OF THE InNH3 COMPLEX

15 min

9:39

GRETCHEN K. ROTHSCHOPF, SHENGGANG LI, JIMMYE SHANNON PERKINS, AND DONGSHENG YANG, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055. FD05 ZEKE-PFI SPECTRA OF AlNH3 AND AlNH2 (CH3 )

15 min

9:56

GRETCHEN K. ROTHSCHOPF, JIMMYE SHANNON PERKINS, SHENGGANG LI, AND DONGSHENG YANG, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; JUN MIYAWAKI, National Institute of Materials and Chemical Research, National Institute for Advanced Interdisciplinary Research, Higashi, Tsukuba, Ibaraki 305, Japan.

72

MA. PLENARY MONDAY, JUNE 12, 2000 – 8:45 AM Room: AUDITORIUM INDEPENDENCE HALL Chair: WILLIAM SAAM, The Ohio State University, Columbus, OH

Welcome C. Bradley Moore, Vice President for Research The Ohio State University

8:45

MA01 40 min 9:00 THE STRANGELY FAMILIAR WORLD OF UNFAMILIAR ION-PAIR RYDBERG STATES: EXOTIC ATOMS MADE FROM MOLECULES JOHN W. HEPBURN, Dep’t of Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1, CANADA. We have recently demonstrated that it is possible to produce a new form of Rydberg state by exciting molecules into very high vibrational levels of an excited ion-pair state. a These ”nuclear” Rydberg states share many common features with their hydrogenic analogues, and can be used for a new form of threshold photoionization spectroscopy that is very reminiscent of mass analyzed threshold ionization (MATI) or zero kinetic energy (ZEKE) spectroscopy. This spectroscopy, called TIPPS for threshold ion-pair production spectroscopy, can be used for accurate bond energy determination, b spectroscopy of molecular ions, c , or to study the dynamics of ion-pair production. d This talk will discuss this new form of spectroscopy, and the similarities in behaviour between hydrogenic Rydberg states and nuclear Rydberg states. [Acknowledgements: The work to be discussed in this talk was carried out by the following past and present group members: James Martin, Ralph Shiell, Xiaokun Hu, Qichi Hu, Mohamed Musa. Financial support from NSERC and ACS-PRF is acknowledged] a J.

D. D. Martin and J. W. Hepburn, Phys. Rev. Lett. 79, 3154 (1997) D. D. Martin and J. W. Hepburn, J. Chem. Phys., 8139 (1998) c R. C. Shiell, X. Hu, Q. Hu, and J. W. Hepburn, J. Phys. Chem. A, to be published d R. C. Shiell, X. Hu, Q. Hu, and J. W. Hepburn, Faraday Disc. Chem. Soc., 115, XXX (2000) b J.

73

MA02 40 min 9:45 MOLECULAR PHYSICS STUDIES WITH FREE ELECTRON LASERS AND MOLECULAR DECELERATORS GERARD MEIJER, FOM Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3430 BE Nieuwegein, The Netherlands, http://www.rijnh.nl, and Department of Molecular and Laser Physics, University of Nijmegen, Toernooiveld 1, NL-6525 ED Nijmegen, The Netherlands. At the FOM-Institute for Plasmaphysics ‘Rijnhuizen’ in Nieuwegein, The Netherlands, intense research activity in the field of molecular physics has recently been started. In the ‘molecular dynamics’ group, the unique possibilities offered by the ‘Free Electron Laser for Inrared eXperimnts’ (FELIX) a , a pulsed laser that is continuously tunable throughout the 5–250 m region, are exploited. In a variety of double-resonance experiments, IR spectra of neutral and cationic aromatic hydrocarbons and of their rare-gas van der Waals complexes have been recorded b . IR multiphoton excitation schemes leading to either dissociation or ionization (thermionic electron emission) are used to unravel IR spectral properties of strongly bonded molecules and clusters c . In the ‘cold molecules’ group, pulsed beams of slow dipolar neutral molecules are produced using an array of time-varying electric field stages d . The operation principle of this so-called ‘Stark-decelerator’ has strong similarities to the operation principle of linear accelerators used for charged particles. The pulsed molecular beams exiting the Stark-decelerator can have translational temperatures in the mK range, while their absolute velocity can be tuned over the 300–10 m/s range. These beams hold great promise for a variety of (novel) molecular beam studies, and are ideally suited as an injector for a trap and/or storage ring for neutral molecules. a G.M.H.

Knippels, R.F.X.A.M. Mols, A.F.G. van der Meer, D. Oepts, and P.W. van Amersfoort, Phys. Rev. Lett. 75, 1755 (1995) Piest, G. von Helden, and G. Meijer, J. Chem. Phys. 110, 2010 (1999); R.G. Satink, H. Piest, G. von Helden, and G. Meijer, J. Chem. Phys. 111, 10750 (1999); H. Piest, G. von Helden, and G. Meijer, ApJ, 520, L75 (1999). c G. von Helden, I. Holleman, G.M.H. Knippels, A.F.G. van der Meer, and G. Meijer, Phys. Rev. Lett. 79, 5234 (1997); D. van Heijnsbergen, G. von Helden, M.A. Duncan, A.J.A. van Roij, and G. Meijer, Phys. Rev. Lett. 83, 4983 (1999). d H.L. Bethlem, G. Berden, and G. Meijer, Phys. Rev. Lett. 83, 1558 (1999) b H.

Intermission

TRIBUTE TO K. NARAHARI RAO and RAO AWARDS Presentation of Awards by Arlan Mantz, Connecticut College 1999 Rao Award Winners R. Timothy Bonn, University of Pennsylvania Sachiko Itono, Ochanomizu University Sabine F. Deppe, Universit¨at G¨ottingen COBLENTZ AWARD Presentation of Award by John Hellgeth, Coblentz Society Chair

10:45

74

MA03

Coblentz Society Award Lecture

40 min

11:20

VIBRATIONAL DYNAMICS FROM SMALL MOLECULES TO PROTEINS MARTIN GRUEBELE, Departments of Chemistry and Biophysics, and Beckman Institute for Advanced Science and Technology, University of Illinois, Urbana, Illinois 61801.

75

ME. INFRARED MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1153 SMITH LAB Chair: JEAN VANDER AUWERA, Universit´e Libr´e de Bruxelles, Brussels, Belgium

ME01 NEW EXPANSIONS OF POTENTIAL ENERGY FOR DIATOMIC MOLECULES

15 min

1:30

M. MOLSKI and J. KONARSKI, Theoretical Chemistry Department, A. Mickiewicz University, ul. Grunwaldzka 6, PL 60-780 Pozna´n, Poland.. We introduced new expansions of the internuclear potential energy for diatomic molecules in the form of a power series combining Dunham, Simons-Parr-Finlan and Ogilvie expansionsa , a continued fractionb , and a combination of a power series and Pad´e approximantsc . These functions satisfy all criteria applicable to real potential curves of molecules in a stable electronic state; they asymptotically approach a finite value in the dissociation limit, exhibit a minimum energy at the equilibrium internuclear separation, and approach a positive value greater than a dissociation energy as the separation decreases. The proposed expansions are applied in quantitative analysis of the infrared, microwave and Raman spectra of the selected diatomic molecules. Published wavenumbers of assigned transitions are reproduced with fewer parameters for potential energy than reported elsewhere. a M.

Molski, J. Mol. Spectrosc. 193, 244 (1999). Molski, Phys. Rev. A 60, 3300 (1999). c M. Molski and J. Konarski, unpublished results.

b M.

ME02 A THEORETICAL INVESTIGATION OF THE SILICON-CARBON CHAIN MOLECULE SiC8

10 min

1:47

P. BOTSCHWINA, B. SCHULZ, R. OSWALD, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany; H. STOLL, Institut f¨ur Theoretische Chemie, Universita¨ t Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.

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ME03 15 min 1:59 NC6 N AND NC5 NC: COUPLED CLUSTER CALCULATIONS AND IMPROVED ASSIGNMENTS OF IR AND RAMAN SPECTRA P. BOTSCHWINA, R. OSWALD, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany.

ME04 15 min 2:16 AB INITIO CALCULATION OF CONFORMATIONS AND INFRARED SPECTRA OF MESO AND RACEMIC 2,4PENTANEDIOL D. L. REYNOLDS, N. MINA-CAMILDE, and C. E. MANZANARES, Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798; A. J. HERNANDEZ, and M. C. SALAZAR, Department of Chemistry, Simon Bolivar University, Caracas 1080A,Venezuela. The infrared spectra of meso-2,4-pentanediol and racemic-2,4-pentanediol were measured in an argon isolated matrix at 20 K. The absorptions were obtained using a low temperature cryostat and a Fourier transform infrared spectrophotometer. The meso and racemic forms of the diol were separated by means of a spinning band distillation column. Ab initio molecular orbital calculations were performed to obtain the equilibrium geometry, vibrational frequencies, force fields, and infrared intensities. The calculations were done at the Hartree-Fock level using 6-31++G** basis set.

ME05 15 min 2:33 PHASE SHIFT CAVITY RING DOWN MEASUREMENT OF VIBRATIONAL OVERTONE ABSORPTIONS E. K. LEWIS, X. Li, and C. E. MANZANARES, Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76798; A. J. HERNANDEZ, and M. C. SALAZAR, Department of Chemistry, Simon Bolivar University, Caracas 1080A, Venezuela. Phase-shift cavity ring down absorption spectroscopy with a continuous laser was used to measure the absorption coefficients and integrated cross sections for the fifth overtone of the C-H stretching vibration of ethylene, ethane, propane, n-butane, and n-pentane. The absorption spectrum is obtained by measuring the magnitude of the phase shift that an intensity modulated continuous laser beam experiences upon passing through an optical cavity. The detection sensitivity compares favorably with that of the pulsed laser ’standard’ cavity ring down technique.

Intermission

77

ME06 LEAD SALT SEMICONDUCTOR LASER EMISSION LINESHAPE ANALYSIS

15 min

3:10

B. AOAEH, Y. ABEBE, A. W. MANTZ, Department of Physics, Astronomy and Geophysics, Connecticut College, New London, CT 06320; C. D. BALL and F. C. DeLUCIA, Department of Physics, The Ohio State University, 174 W. 18th Ave., Columbus, Ohio 43210-1106; D. CHRIS BENNER, Department of Physics, College of William and Mary, Box 8795, Williamsburg, VA 23187; M. A. H. SMITH, Atmospheric Sciences Division, MS 401A, NASA Langley Research Center, Hampton, VA 23618-2199.

ME07 15 min 3:27 MEASUREMENTS OF 1-0 BAND OF CARBON MONOXIDE AT TEMPERATURES BETWEEN 11 AND 296 KELVINS B. AOAEH, N. KOLODZIEJSKI, A. W. MANTZ, Department of Physics, Astronomy and Geophysics, Connecticut College, New London, CT 06320; D. CHRIS BENNER, V. MALATHY DEVI, Department of Physics, College of William and Mary, Box 8795, Williamsburg, VA 23187-8795; M. A. H. SMITH, Atmospheric Sciences Division, MS401A, NASA Langley Research Center, Hampton, VA 23618-2199; C. D. BALL and F. C. DeLUCIA, Department of Physics, The Ohio State University, 174 W. 18th Ave., Columbus, Ohio 43210-1106.

78

ME08 15 min 3:44 SUB-DOPPLER SPECTROSCOPY OF THE C–O STRETCHING FUNDAMENTAL BAND OF METHANOL BY USING MICROWAVE SIDEBANDS OF CO2 LASER LINES Z. D. SUN,F. MATSUSHIMA, S. TSUNEKAWA, AND K. TAKAGI, Department of Physics, Toyama University, Toyama 930-8555,Japan. The infrared spectra of the C–O stretching fundamental band of methanol have been studied for the (t , E , K ) = (1, E , 2) and (1, E , 5) sequences by a CO2 sidebands laser sub-Doppler spectrometer a . The R- and Q-branch transitions of co =1 0 for these two level sequences have been assigned and their frequencies have been measured with an accuracy of 0.15 MHz. These assignments have been made by observing Stark effects and by using the Ritz’s combination principle. For R-branch lines of the (1, E , 2) sequence, the observed frequencies agree with the results of Lees et al. b within experimental uncertainties. As for transitions belonging to the (1, E , 5) sequence, which was assigned only for R(6), Q(7) and P(8) previously, c transitions involving J = 5, 7, 9, 10, 12, 14 and 16 have been assigned. Term values of the observed transitions of the (1, E , 2) and (1, E , 5) sequences in the t = 1 state have been given by using the ground state term values in Ref. 3 and their Taylor series expansion coefficients of J (J + 1) have been determined by a least-squares fit.

a Z. D. Sun, F. Matsushima, S. Tsunekawa and K. Takagi, paper RJ06 at the “54th Ohio State University International Symposium on Molecular Spectroscopy”, Columbus, Ohio (1999). b R. M. Lees, I. Mukhopadhyay, and J. W. C. Johns, Opt. Commun. 55, 127(1985), c G. Moruzzi, B. P. Winnewisser, M. Winnewisser, I. Mukhopadhyay, and F. Strumia, Microwave, infrared and laser transitions of methanol, Atlas of assigned lines from 0 to 1258 cm 1 , (CRC Press, Boca Raton, Fla, 1995).

ME09 15 min 4:01 OBSERVATION OF DRESSED MOLECULES IN NEAR INFRARED-RF DOUBLE RESONANCE SPECTROSCOPY OF CH3 I CHIKAKO ISHIBASHI, RYUJI SANETO, and HIROYUKI SASADA, Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan. Near infrared-radio frequency (rf) double-resonance spectroscopy of the vibrational overtone band of CH3 I molecules has been carried out. To record saturated absorption lines of the near-infared transitions, we employed an optical Fabry-Perot cavity absorption cell a and a frequency modulation technique b . The rf field tuned with the hyperfine transition was applied through a pair of copper plates inserted in the Fabry- Perot cavity cell. Then the saturated absorption lines were split into two components separated by 1 MHz due to the ac-Stark effect. Two types of crossover reosnances were also observed; one appears at the center frequency of the two near-infrared transitions that share either upper or lower level of the rf transition, and the others lie at the middle of the two components split by the ac-Stark effect. Quantum interference phenomena were also observed. All the spectral features have been well expressed in terms of the dressed-molecule picture of a four-level system c . a M.

de Labachelerie, K. Nakagawa, and M. Ohtsu, Opt. Lett. 19, 840 (1994) Ye, L. S. Ma, and J. L. Hall, Opt. Lett. 21, 1000 (1996) c C. Cohen-Tannoudji, J. Dupont-Roc, and G. Grynberg, ”Atom-Photon Interactions”, Wiley Interscience, New York (1992).

b J.

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ME10 15 min 4:18 VIBRATION-ROTATION FLUORESCENCE SPECTRA OF WATER IN THE GROUND ELECTRONIC STATE MARIA SAARINEN, DMITRI PERMOGOROV, Laboratory of Physical Chemistry, P.O. Box 55 (A. I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland; LAURI HALONEN, JILA, University of Colorado, Campus Box 440, Boulder, Colorado 80309. Laser-induced fluorescence has been used to investigate overtone states of water. Specific rovibrational states have been excited by a high-resolution Titanium:Sapphire ring laser in the near-infrared region. The resulting fluorescence light around 3000 - 4000 cm 1 has been dispersed by a Fourier transformation interferometer. Rich collision-induced spectra are obtained. The specific nuclear spin states chosen by the laser excitation are conserved in collisional processes. Variational calculations with an internal coordinate Hamiltonian and a dipole surface have reproduced interesting experimental emission intensity effects. ME11 NEW INFRARED EMISSION MEASUREMENTS ON HNC

10 min

4:35

ARTHUR MAKI, 15012 24th Ave. S.E., Mill Creek, WA 98012; GEORG MELLAU, Physikalisch-Chemisches Institut, Justus-Liebig-Universit¨at, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany.

ME12 PRECISE TRANSITION FREQUENCY MEASUREMENTS OF CH4 IN THE 1.66 m REGION

15 min

4:47

CHIKAKO ISHIBASHI, KOTARO SUZUMURA, and HIROYUKI SASADA, Department of Physics, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, 223-8522, Japan; MOTONOBU KOUROGI, KAZUHIRO IMAI, and BAMBANG WIDIYATMOKO, Graduate School at Nagatsuta, Tokyo Institute of Technology, 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8502, Japan; ATSUSHI ONAE, National Research Laboratory of Metrology, 1-1-4, Umezono, Tsukuba 305-8563, Japan. Sub-Doppler resolution laser spectroscopy with high sensitivity and wide tunability was presented by some of the authors (C. I. and H. S.) last year a . There we used a Fabry-Perot cavity absorption cell, an external-cavity diode laser (ECDL), and a frequency modulation technique, which drastically improved the performance of the spectrometer b . Because the spectral resolution was attained as high as 320 kHz, the corresponding precision has been required in the frequency measurement. To this end, we stabilized the ECDL’s frequency to the narrow saturation dip of CH4 of the 23 band in the 1.66 m region, and made two kinds of precise frequency measurements. First, we stabilized two ECDL’s frequency to different spectral lines respectively, and measured the frequency of the optical beat note between the ECDL’s. Sixty-six frequency differences were measured with an accuracy of 40 kHz.c The second is the absolute frequency measurement. We used a 1.54-m saturated absorption line of 13 C2 H2 as a frequency reference and an optical frequency comb generator for bridging the 14-THz frequnecy gap between the 1.66 m and 1.54 m radiations. The absolute frequencies of the R(0) and Q(1) transitions were determined to be 180:345 065 08(37) and 180:021 253 10(61) THz, respectively.d a C.

Ishibashi and H. Sasada, Proc. of 54th Ohio State Univ. Int. Symp. Molec. Spectrosc.RJ04, 237 (1999) Ishibashi and H. Sasada, Jpn. J. Appl. Phys. 38, 920 (1999) c K. Suzumura, C. Ishibashi, and H. Sasada, Opt. Lett.22, 1356 (1999) d C. Ishibashi, M. Kourogi, K. Imai, B. Widiyatmoko, A. Onae, and H. Sasada, Opt. Commun.161, 223 (1999) b C.

80

ME13 15 min 5:04 CHARACTERIZATION OF ADSORPTION EFFECTS ON METALLIC SURFACES OF POLAR MOLECULES IN THE GAS PHASE BY FT-IR SPECTROSCOPY E. H. DOWDYE, and C. HARIDASS, Laser Spectroscopy Laboratory, Department of Physics & Astronomy and Center for the Study of Terrestrial & Extraterrestrial Atmospheres, Howard University, Washington, DC 20059; P. MISRAa , NASA Goddard Space Flight Center, Laser & Electro-Optics Branch, Code 554, Greenbelt, MD 20771. A Nicloet Magna-IR 550 FT-IR spectrometer fitted with a 10-m path length multipass absorption cell was used to determine the changes in concentration at parts-per-million level of polar molecules (HCl and NH3 ) when the gases were passed from the main reservoir to the absorption cell through tubings made of copper and aluminum. The observed changes in concentration were correlated to the degree of adsorption of the gas on the solid material and aided in the determination of the corresponding rate constants. A systematic study of the interaction of HCl and NH3 with copper and aluminum permitted an estimate of the corrected concentration deficit due to adsorption and facilitated the fit of the observed data to the Langmuir adsorption isotherms. a 1999-2000

NASA Administrator’s Faculty Fellow at Goddard Space Flight Center

ME14 DIMENSIONAL EFFECT ON IR ABSORBTION BAND CONTOUR OF BENZENE

15 min

5:21

E. N. SHERMATOV, Samarkand State University, Univ. bulv 15, 703004 Samarkand, Uzbekistan. IR absorption 673 cm 1 band contour for gaseous and liquid benzene was studied. For gaseous benzene the contour involves narrow Q-branch and two side P and R-branches. Distance between P and R-branch is (
yP R = 26 cm 1 . Absorption band of liquid benzene at 3-5 mkm layer thick involves central Q-branch. With increasing of layer thick the band contour deformation and the disappearing of Q- branch has been found. At layer thick more 15 mkm the band contour involves two side branches the distance between which is approximately agrees with those for gas phase. As a result of phase correlation and selforganization in liquid the superimposed oscillating wave packets are formed. They form lateral components in absorption spectrum. At small layer thicks due to the disturbance of phase correlation takes place the nonsymmetric transitions of energy. They form the Q-branches. With the increase of layer thick due to realization of phase correlation takes place the disappearing of Q- branch.

81

MF. JET AND BEAM MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1009 SMITH LAB Chair: TIMOTHY G. WRIGHT, University of Sussex, Brighton, United Kingdom

MF01 15 min 1:30 HELIUM AND HYDROGEN INDUCED ROTATIONAL RELAXATION OF H2 CO OBSERVED AT TEMPERATURES OF THE INTERSTELLAR MEDIUM MARKUS MENGEL and FRANK C. DE LUCIA, Department of Physics, The Ohio State University, 174 West 18th Ave., Columbus OH 43210, USA. We have performed pressure broadening and time resolved double resonance studies on three rotational transitions (212 111 , 211 110 , and 313 212 ) of formaldehyde (H2 CO) in collision with helium and hydrogen at low temperatures (T  16 K). This was achieved by applying the collisional cooling method. The purpose of this study was to compare laboratory measurements with the theory used to explain the anomalous absorption of interstellar formaldehyde against the 2.7 K background.a We can confirm this prediction as far as it constitutes a model based on H2 CO - He collisions. However, we observe significantly different pressure broadening cross sections for H2 CO - H2 collisions which raises the question as to whether a simple transfer from helium to hydrogen as collision partner can be made. a B.J.

Garrison, W.A. Lester Jr., and W.H. Miller, J. Chem. Phys. 65, 2193-2200 (1976)

MF02 15 min 1:47 INFRARED SPECTROSCOPY OF THE HCN-(H2 /D2 )n CLUSTERS IN THE SUPERFLUID HELIUM DROPLETS MASAZUMI ISHIGURO, ROGER E. MILLER, Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599. The Superfluid He droplet is an ideal matrix for making large sized molecular clusters, because of its extremely low temperature (T < 0.5 K) and very weak interaction with molecules. In this study, we observed vibrational spectra for the CH stretching band of the HCN-(H2 /D2 )n clusters in the He droplets under a strong electric field (30 kV/cm). For the HCN-(H2 )n system, HCN-(o-H2 )n (n = 1 5), HCN-(p-H2 )n (n = 1 3), and HCN-(o-H2 )1 (p-H2 )1 have been observed. Since o-H2 (j = 1) has a quadrupole moment, it is supposed that the interaction between o-H2 and HCN is stronger than that between p-H2 (j = 0) and HCN. Nevertheless, the observed red-shift of the CH-stretching band for HCN(o-H2 )n is much smaller than that of HCN-(p-H2 )n . This phenomenon strongly suggests that the geometrical structure for HCN-(o-H2 )n and that for -(p-HCN)n are distinctly different. That is, in HCN-(o-H2 )n , the H2 molecules are bonding to the N site of HCN. Contrastedly in HCN-(p-H2 )n , the H2 molecules are bonding to the H site of HCN, and affect strongly to the CH-stretching vibration. For the HCN-(D2 )n system, we obtained the same conclusion. In addition to the vibrational spectra under the strong electric field, we mention vibrational-rotational spectra for HCN(H2 /D2 )1 clusters under the field-free condition.

82

MF03 15 min 2:04 HIGH RESOLUTION INFRARED SPECTROSCOPY OF THE HCN-(o-H2 ) AND HCN-(p-D2 ) CLUSTERS IN THE GAS PHASE MASAZUMI ISHIGURO, ROGER E. MILLER, Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599. High resolution infrared spectra of of the HCN-(o-H2 ) and -(p-D2 ) in the gas phase have been observed and analyzed for the first time. Spectra for the CH-stretching band were recorded by using a color center laser spectrometer combined with molecular beam opto-thermal detection. No spectra for HCN-(p-H2 ) and HCN-(o-D2 ) were observed. The observed spectra for HCN-(o-H2 ) and (p-D2 ) show a typical pattern for parallel band of a linear molecule. Since the Q-branches were absent and the R(0) lines were observed, these bands were assigned to   bands. The rotational constants, B 0 , obtained from Dopplar free spectra (FWHM = 20 MHz) were 0.43025(18) cm 1 and 0.26630(8) cm 1 for HCN-(o-H2 )1 and for -(p-D2 )1 , respectively. For both species, the line broadening due to vibrational predissociation has not been observed. The vibrational frequencies for the vdW stretching mode were derived to be 30.2 cm 1 and 28.4 cm 1 for HCN-(o-H2 ) and -(p-D2 ), respectively.

MF04 MILLIMETER-WAVE SPECTROSCOPY OF THE HCN-H2 CLUSTER

10 min

2:21

M. ISHIGURO and T. TANAKA, Department of Chemistry, Faculty of Science, Kyushu University 33, Hakozaki, Higashiku, Fukuoka 812-8581, Japan; C. J. WHITHAM, K. HARADA and K. TANAKA, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan. Millimeter-wave absorption spectroscopy combined with a pulsed-jet expansion technique was applied to the measurement of the rotational and rovibrational transitions of the HCN-H2 cluster in the frequency region of 75 150 GHz. So far, four rotational lines for the ground 0 state of the HCN-(o-H2 ) cluster split into hyperfine structure due to the nitrogen nucleus were observed. Rotational constant B0 = 12899:718(20) MHz and centrifugal distortion constant D0 = 12:2470(16) MHz were derived together with its higher constants. The hyperfine constants determined eqQ = 2:830(33) MHz which is smaller than that of HCN molecule means a large amplitude motion of HCN of <  > = 31.1 degree in the ground linear ˚ form. The bond length between HCN and H2 parts is derived to be 3.90 A. Some lines belonging to the 1 0 van der Waals bending band of HCN-(o-H2 ) were also observed. The 1 0 van der Waals bending frequency 136.831 GHz of HCN-(o-H2 ) is larger than that of He-HCN 98.70 GHz, but much smaller than that of Ar-HCN 164.89 GHz. The hyperfine constant in the 1 state indicate the cluster has T-shape in the excited state of the vdW bending mode. A search of the rotational lines of the ground 0 state of HCN-(p-H2) and the 0 state of HCN-(o-H2 ) are now in progress as well as the vdW mode rovibrational lines for both HCN-(o-H2 ) and -(p-H2 ) clusters.

83

MF05

10 min 2:33 3 DIRECT OBSERVATION OF THE 2 u STATE OF Rb2 IN A PULSED MOLECULAR BEAM: ROTATIONAL+ BRANCH INTENSITY ANOMALIES IN THE 2 3 u (1u ) X 1 + g (0g ) BANDS Y. LEE,Y. YOON, S. J. BAEK, D-L JOO, J-S RYU and B. KIM, Department of Chemistry, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea. 3 The first observation of 2 3 u X 1 + g transitions is reported. Rotationally resolved transitions of the 2 u (1u ) 3 + 1 + + 1 + + X g (0g ) and 2 u (0u ) X g (0g ) are observed by resonance enhanced 2-photon ionization (RE2PI) method in a pulsed molecular beam. -doubling and interference induced rotational branch intensity anomalies are observed for 2 3  (1 ) X 1 + (0+ ) transitions. Both of 2 3  (0+ ) and 2 3  (1 ) states are strongly mixed with singlet states by u u u u u u g g 1 3 spin-orbit coupling. The former with 2 1 + u and the latter with 2 u . In relatively weak 2 u (1u ) bands P branch rotational lines disappear and the intensities of R branch rotational lines are enhanced. These intensity anomalies in 2 3  (1 ) X 1 + (0+ ) transition, due to an interference effect between parallel and perpendicular transition amplitudes, u u g g 1 + + is caused by
= 1 perturbation. The molecular constants of 2 3 u (0+ u ) X g (0g ) transition are determined as 1 1 Te = 19784:2588  0:0088 cm , !e = 42:1954  0:0060 cm , !e xe = 0:1701  0:0011 cm 1 , !e ye = 0:001096  0:000057 cm 1 , Be = 0:018503  0:000018 cm 1 for 8 5Rb2 . The spin orbit coupling constant A and -doubling + parameters p and q are determined by simultaneous fitting of the rotational contours of both 2 3 u (1u ) X 1 + g (0g ) and 3 + 1 + + 2 u (0u ) X g (0g ) transitions.

MF06 10 min 2:45 POLARIZATION QUAMTUM BEAT SPECTROSCOPY OF NO2 : HYPERFINE LEVEL STRUCTURE IN THE YELLOW REGION(16000-19250 CM 1 ) JU XIN AND SCOTT A. REID, Department of Chemistry, Marquette University, Milwaukee, WI 53201-1881. We report on the application of fluorescence-based polarization quantum beat spectroscopy to probe the excited hyperfine level structure of NO2 vibronic bands in the yellow region (16000-19250 cm 1 ). Two general trends are observed when comparing our results with spectroscopic studies at lower energy. First, fluctuations in the Fermi-contact interaction dampen with increasing energy. Second, the magnitude of this interaction decreases with increasing enegy. We will dscuss possible explanations for and implication of these trends.

Intermission

84

MF07 15 min 3:15 VRT-SPECTROSCOPY IN THE TRANSLATIONAL AND LIBRATIONAL BAND REGION OF LIQUID WATER: HYDROGEN BOND TUNNELING DYNAMICS IN WATER CLUSTERS F. N. KEUTSCH, R. S. FELLERS, P. B. PETERSEN, M. R. VIANT, M. G. BROWN, and R. J. SAYKALLY, Department of Chemistry, University of California Berkeley, Berkeley, CA 94720. We report the observation of a new vibration-rotation-tunneling (VRT) band of (D2 O)3 at 142.8 cm 1 and a set of four bands of (H2 O)3 around 520 cm 1 . These new bands represent the first observation of a translational and librational vibration for a water cluster. The observed VRT spectrum of (D2 O)3 at 142.8 cm 1 , in the translational band of the liquid, is assigned to a combination band or mixed level of the asymmetric hydrogen bond stretch and a torsional vibration. The predicted frequencies of the hydrogen bond stretching modes are too high, presumably because calculations fail to include the necessary coupling between stretching and torsional motions a . The bands of (H2 O)3 around 520 cm 1 lie in the librational band region of liquid water and are tentatively assigned to the out of plane librational vibration. The observation of at least four bands within 8 cm 1 is explained by a dramatically increased splitting of the excited state rovibrational levels by bifurcation-tunneling. The experimental results presented should therefore allow for the first exact determination of the height of the bifurcation tunneling barrier. The tunneling time scale is estimated at 2-4ps, similar to those of several important dynamical processes in bulk water b . a W. b A.

Klopper, M. Schutz, H. P. Luthi, S. Leutwyler, J. Chem. Phys. 103, 1085 (1995). Luzar, D. Chandler, Nature 379, 55 (1996).

MF08 15 min 3:32 THE DEPENDENCE OF INTERMOLECULAR INTERACTIONS UPON VALENCE COORDINATE EXCITATION: THE vHF =4 LEVELS OF ArHF CHENG-CHI CHUANG, and WILLIAM KLEMPERER, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138. The valence state dependence of the Ar HF interaction potential is extended to vHF = 4. Three new ArHF (vHF = 4) states, (4000), (4100), and (4110), are observed between 14780 and 14880 cm 1 using intracavity laser induced fluorescence. The spectroscopic constants of these states are: (4000) 0 = 14783.60323(30) cm 1 , and B = 0.1036068(68) cm 1 ; (4100) 0 = 14867.41906(70) cm 1 , B = 0.102612(27) cm 1 ; and (4110) 0 =14875.04673(31) cm 1 , B = 0.1012823(73) cm 1 respectively. In conjunction with the previous ArHF results (vHF =0 3), the spectral red shifts of ArHF(v 000) increase more rapidly than linearly, from 9.654 cm 1 at v =1 to 48.024 cm 1 at v =4. The rotational constants of ArHF(v 000) increase essentially linearly with vHF , noticeably increased by 1.30 % (40 MHz) at v =4. The classical turning point of HF ˚ from re at v =4, showing no evidence for Ar H repulsion. The spectral red shift for linear hydrogen is extended by 0.4 A bonded Ar HF (v 000) indicates a strong enhancement of binding energy upon HF valence bond elongation, while the rotational constant indicate an almost surprising decrease in heavy atom separation. Both the T-shaped ArHF(v 110) and anti-linear Ar FH(v 100), however, show very little dependence of binding energy upon vHF valence excitation. These observations are in good accord with the ab initio calculations of the Ar HF intermolecular potential surface.

85

MF09 15 min 3:49 AN AB INITIO STUDY ON THE EXPLICIT rXF DEPENDENCE OF THE INTERMOLECULAR POTENTIALS OF ArHF AND ArClF: WHEN DOES Ar-X REPULSION BEGIN TO SHOW? KELLY J. HIGGINS, and WILLIAM KLEMPERER, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138. The dependence of the ArHF intermolecular potential upon vHF is now known through experiment for vHF = 0 4. For the ground state hydrogen-bonded structure Ar-HF it can be characterized by an increasing red shift and increasing rotational constant as the HF is stretched from v = 0 to v = 4. This indicates that the intermolecular bond is getting stronger and the heavy atom distance (Ar-F) is shrinking. Less well known is the explicit rHF dependence of the potential and at what point will the Ar-H repulsion become evident? In addition, does this same behavior extend to other, non-hydrogen bonded systems? In order to answer these and other questions, CCSD(T) ab initio calculations have been performed on ArHF and ArClF to generate full three-dimensional (R; ; r ) potential energy surfaces for a wide range of rXF values. In addition, three-dimensional quantum calculations of the bound states for the two systems have been performed to provide comparison with experiment and predictions for future experiments. The results for ArHF are in excellent agreement with experiment in terms of red shift and change in rotational constant. They predict that the increase in the red shift will slow at vHF = 7 and turn around at vHF = 9. While this is well beyond current experimental accessibility, the results also predict that the rotational constant should be smaller for ArHF vHF = 5 than for vHF = 4, thus showing the first signs of Ar-H repulsion. ArHF vHF = 4 experimental results have recently been obtained by Chuang and Klemperer, and ArHF vHF = 5 should be accessible with their current set-up. The intermolecular potential of ArClF shows a dramatic increase in depth for wells at both ends of ClF upon stretching of the ClF bond. Accompanying this is a decrease in Ar-Cl and ˚ , at which point the well depths begin to decrease and the atom-atom distances begin Ar-F distance until rClF = 2:0A to increase. Bound state calculations show a steady increase in red shift and a steady decrease in Ar-Cl distance from vClF = 0 to at least vClF = 11 for the ground state Ar-ClF configuration. It appears the increase in binding energy and the decrease in intermolecular distance upon stretching of the HF bond observed in ArHF is a general phenomena in atom-diatomic molecule systems.

MF10 15 min 4:06 A SUB-DOPPLER RESOLUTION DOUBLE RESONANCE MOLECULAR BEAM INFRARED SPECTROMETER OPERATING AT 2eV: INVESTIGATION OF HCN AND HCCH HEMANT SRIVASTAVA, ANDRE´ CONJUSTEAU, KEVIN K. LEHMANN, and GIACINTO SCOLES, Department Of Chemistry, Princeton University, Princeton NJ 08544; HIDEO MABUCHI, Department Of Physics, California Institute Of Technology, Pasadena, CA 91125; ANDREA CALLEGARI, Laboratoire ´ De Chimie Physique Mol´eculaire (LCPM), Ecole Polytechnique F´ed´erale De Lausanne, CH-1015 Lausanne, Switzerland. A molecular beam spectrometer capable of achieving sub-doppler resolution around 2 eV (18000 cm 1 ) of vibrational excitation has recently been built in our laboratory. Two high finesse resonant power-buildup cavities are used to excite the molecules using a sequential double resonance technique. A v = 0 ! 2 transition is first saturated using a 1.5 m color center laser. Downstream, a fraction of the molecules is further excited to the v = 6 level upon interacting with a chopped Ti:Al2 O3 laser. The energy absorbed by the molecules is detected on a cryogenically cooled bolometer via phase sensitive detection. A resolution of approximately 15 MHz, corresponding to three parts in 108 and scan speeds of up to several reciprocal centimeters per hour were obtained, with signal-to-noise ratios in excess of 100. The performance of the spectrometer is demonstrated by probing a rotational in the v=6 manifold of the CH stretch chromophore of HCN. We also report the spectra of the v=6 CH stretch excitation for 12 C2 H2 , where a total of 13 transitions in the (006+) band have been recorded. Despite the low density of states (a few per cm 1 ), two J states are split into two components. Analysis of the coupling coefficients indicates that different perturbers are responsible for each of the splittings, which means that the perturbing states rapidly tune into and out of resonance.

86

MF11 15 min 4:23 MILLIMETER WAVE SPECTROSCOPY OF THE VAN DER WAALS BENDING BAND OF He-HCN WITH A MULTIREFLECTION JET CELL KENSUKE HARADA, CHRISTOPHER JAMES WHITHAM, AND KEIICHI TANAKA, Institute for Molecular Science, Okazaki, 444-8585, Japan. The He-HCN cluster is a weakly bound cluster with a binding energy of only 9 cm 1 .a ; b Previously, two van der Waals transitions were reported by electric resonance spectroscopy.a In the present study, a number of new j=1-0 van der Waals bending transitions predicted below the dissociation limitb have been observed in 95-125 GHz region with a high sensitivity multi-reflection millimeter wave jet cell. 10 round trip optical paths were used in the measurement. We used a pulsed jet nozzle and the jet cell was evacuated by a diffusion pump. We have measured 13 Q-branch lines up to l=4 with j=1-0 where l and j are the rotational quantum number of the cluster and the HCN subunit. The lines were fitted to a Hamiltonian expanded using a anisotropic intermolecular potential. The potential function was determined to be V = - 2.2530(43) P1 (cos) - 0.665(62) P2 (cos) - 0.45(17) P3 (cos) (in cm 1 units) and shows a large anisotropy with respect to the angle  between the HCN and the intermolecular cluster axis. a S. b K.

Drucker, Fu-Ming Tao, W. Klemperer, J. Phys. Chem. 99, 2646 (1995). M. Atkins, J. M. Hutson, J. Chem. Phys. 105, 440 (1996).

MF12 INFRARED SPECTRUM OF THE CO-NH3 COMPLEX

15 min

4:40

CHANGHONG XIA and A.R.W. McKELLAR, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada. We have observed the IR spectrum of the weakly-bound complex CO-NH3 in the C-O stretching region using a rapid scan diode laser spectrometer with a pulsed slit-jet supersonic expansion. A New Focus model 5612 astigmatic mirror system, mounted inside the vacuum chamber, gave 182 passes of the laser beam through the jet. With neon as the carrier gas, only weak CO-NH3 signals could be observed; the best spectra were obtained using argon as the carrier (1 % NH3 , 9 % CO, 90 % Ar). The only previous spectrum of CO-NH3 was obtained in the microwave region using MBER.a It revealed a ‘normal’ K = 0 ground state series, two other almost-degenerate K = 0 excited state series, and two degenerate K = 1 excited series. The proposed structure had CO located close to the N atom in an undetermined orientation, with the NH3 symmetry axis at an angle of about 36Æ relative to the intermolecular axis. 0, 0 0, and 0 1 for which the ground state In the IR spectrum, we assign a ‘normal’ set of subbands with K = 1 (vCO = 0) K = 0 levels are those of the ‘normal’ microwave series. The band origin lies only 0.11 cm 1 below that of the free CO molecule. The K = 0 to 1 energy interval is found to be 2.24 cm 1 ; this value, and the fact that the parallel subband is weak, suggest that the CO is oriented roughly perpendicular to the intermolecular axis. The analysis indicates that an unassigned microwave line [1] at 14158 MHz is due to the 211 - 110 transition. The ‘normal’ subbands closely resemble those seen for CO-Ne or CO-Ar, and we believe that they are due to the lowest NH3 internal rotation state of A symmetry. In addition to these ‘normal’ subbands, we also observe other series which are associated with the excited transitions observed in the microwave spectrum. These are likely due to internal rotation states of E symmetry. a G.T.

Fraser, D.D. Nelson, K.I. Peterson, and W. Klemperer, J. Chem. Phys. 84, 2472 (1986).

87

MF13 15 min 4:57 IR SPECTRUM OF THE CO-N2 COMPLEX: ASSIGNMENTS FOR CO-paraN2 AND OBSERVATION OF A BENDING STATE FOR CO-orthoN2 CHANGHONG XIA, A.R.W. McKELLAR, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada; YUNJIE XU, Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada. The infrared spectrum of the weakly-bound complex CO-N2 has been studied using a pulsed supersonic slit-jet and a rapidscan tunable diode laser. A mirror system giving 182 passes of the laser through the jet helped to give improved spectra with lower effective rotational temperatures (0.5 to 4 K) and less interference by CO dimer transitions. In the case of the CO-paraN2 spin modification, for which only one subband was previouslya known, over 10 linked subbands were assigned in terms of three ground (vCO = 0) state stacks of levels (with K = 0 and 1), and 7 excited state (vCO = 1) stacks (with K = 0, 1, and 2). The infrared analysis relied on precise ground state energy level differences obtained from microwave data.b There is a strong Coriolis interaction between the K = 0 and 1e stacks of levels in both the ground and excited states. However, their energy ordering changes, with K = 0 being lower for vCO = 0, and K = 1 being lower for vCO = 1. For the more abundant nuclear spin modification of the complex, CO-orthoN2 , an excited bending state was observed for the first time. The bending frequency is 4.67 cm 1 . a Y. b Y.

Xu and A.R.W. McKellar, J. Chem. Phys. 104, 2488 (1996). Xu and W. J¨ager, J. Chem. Phys., submitted (2000).

MF14 15 min 5:14 JET SPECTROSCOPY OF THE H-F OUT-OF-PLANE LIBRATIONAL FUNDAMENTAL BAND OF HYDROGEN FLUORIDE PENTAMER IN THE 741 cm 1 REGION THOMAS A. BLAKE, Pacific Northwest National Laboratory, P. O. Box 999, Mail Stop K8-88, 3020 Q Avenue, Richland, WA 99352 (PNNL is operated for the US Department of Energy by the Battelle Memorial Institute under contract DE-AC06-76RLO 1830). Using our pulsed slit-jet, infrared diode laser spectrometer, we have observed a rotationally-resolved parallel band centered at 741 cm 1 in a molecular beam formed by expanding a mixture of 4% HF in helium through a 200 m x 12 cm slit with a backing pressure of ca. 1000 Torr. A set of excited and ground state spectroscopic constants were fit simultaneously to a data set of 75 transitions using a symmetric top, rigid rotor Hamiltonian. The fit constants are  0 = 740:9696(7) cm 1 , B 0 = 0:07507(5) cm 1 , (C 0 B 0 ) (C 00 B 00 ) = 0:0014(1) cm 1 , and B 00 = 0:07570(5) cm 1 . Recently, we have reported the observation of two librational bands of HF tetramer in the 710 to 775 cm 1 region: one band is a perpendicular band centered at 752 cm 1 and the other band is a parallel band centered at 714 cm 1 . The ground state B value of the tetramer was found to be 0:132081(1) cm 1 . For hydrogen fluoride tetramer and pentamer, theory predicts (Maerker, et al.) a planar, oblate symmetric top structures at their global minima with Be values of 0:136 and 0:0767 cm 1 for (HF)4 (C4h symmetry) and for (HF)5 (C5h symmetry), respectively. We have assigned the 741 cm 1 band as the (A00 ) HF out-of-plane librational fundamental of the pentamer, the 714 cm 1 band as the (Au ) HF out-of-plane librational fundamental of the tetramer, and the 752 cm 1 band as the (Eu ) HF in-plane librational fundamental of the tetramer. a C.

Maerker, P. R. Schlyer, K. R. Liedl, T. -K. Ha, M. Quack, M. A. Suhm, J. Comp. Chem. 18 1695 (1997).

88

MG. NEGATIVE IONS MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1000 McPHERSON LAB Chair: JOHN MAIER, University of Basel, Basel, Switzerland

MG01

Journal of Molecular Spectroscopy Special Review Lecture

30 min

1:30

SPECTROSCOPY AND DYNAMICS OF CLUSTER ANIONS W. CARL LINEBERGER, JILA and Department of Chemistry, University of Colorado, Boulder, CO 80309. Spectroscopic studies of mass selected negative ion clusters have provided a wealth of new information concerning the structure, dynamics and energetics of small negative ions and solvated ions. Both bound- bound and bound-free spectroscopies have been employed to give new information on radicals, reactive intermediates and transition states. In this lecture, we discuss new measurements in both the time and frequency domains, emphasizing the very close interplay between theory and experiment that has characterized so much of the advance in the understanding of larger clusters. Particular emphasis will be placed on the structure of solvent about a chromophore, energy transfer from a photodissociated ionic chromophore to the solvent, and the role of electron transfer in the caging process.

MG02

15 min

2:05

FEMTOSECOND STIMULATED EMISSION PUMPING OF BARE AND CLUSTERED I2 ALISON V. DAVIS, MARTIN T. ZANNI, CHRISTIAN FRISCHKORN, Department of Chemistry, University of California, Berkeley, CA 94720; MOHAMMED ELHANINE, Laboratoire de Photophysique Mol´eculaire du CNRS, Bˆatiment 210, Universit´e Paris Sud, 91405 Orsay, France; and DANIEL M. NEUMARK, Department of Chemistry, University of California, Berkeley, CA 94720. Stimulated emission pumping in conjunction with femtosecond photoelectron spectroscopy has been used to create and ~ 2 +u ) state of I2 , both barea and clustered with monitor a coherent superposition of vibrational levels on the ground (X b four CO2 molecules . In the bare ion, the resulting wavepacket oscillations were monitored at several excitation energies up to 0.993 eV; energy-dependent frequencies and anharmonicities were extracted which were used to fit the ground state to a modified Morse potential. In the cluster, which was studied with 0.53 eV excitation energy, the rate of energy loss to the CO2 molecules was determined both by the increase in the wavepacket oscillation frequency (3.8 cm 1 /ps during the initial three picoseconds of coherence) and by the shift of the measured photoelectron spectrum. a M. b A.

T. Zanni, A. V. Davis, C. Frischkorn, M. Elhanine and D. M. Neumark J. Chem. Phys, submitted V. Davis, M. T. Zanni, C. Frischkorn, M. Elhanine and D. M. Neumark J. Electron Spectrosc. Relat. Phenom., submitted

89

MG03 STRUCTURE OF Sin CLUSTER ANIONS: COMPARISON OF THEORY AND EXPERIMENT

15 min

2:22

¨ Universit¨at Konstanz, 78457 Konstanz, Germany; B. LIU and K. HO, ¨ J. MULLER and G. GANTEFOR, Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames Iowa 50011; A.A. SHVARTSBURG and K.W.M. SIU, Department of Chemistry, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J1P3; S. OGUT and J.R. CHELIKOWSKY, Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455. We have measured photoelectron spectra for silicon cluster anions with up to 50 atoms. For species with up to 20 atoms, the spectra have been compared with DFT simulations for a number of candidate low-energy geometries.a An excellent agreement with experiment specific to the lowest-energy Sin anion geometries (Fig.1) validates the morphologies of medium-sized Si clusters based on the tricapped trigonal prism unit. HOMO-LUMO gaps do not decrease with increasing cluster size, but vary irregularly in the 1-2 eV range. The PES data for larger clusters with n > 25 reveal a peculiar electronic structure for Si33 and Si43 anions.

Si8 2

3

Si17 4

5

2

3

Si18 4

5

2

3

4

5

6

Binding Energy [eV] Fig.1: Comparison between simulated and measured PES spectra of Si8 , Si17 , and Si18 . a A.A.

Shvartsburg et al., J. Chem. Phys. 112 (2000)

MG04 SPECTROSCOPIC STUDY OF THE STEPWISE SOLVATION OF CN


(H2 O)n VIA IR-VPS

10 min

2:39

C. K. WONG, J. D. LOBO, M. OKUMURA, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125. IR Vibrational Predissociation Spectra of CN
(H2 O)n , anionic clusters, where n = 2 through 6, were obtained in the 2900 to 3900 cm 1 region. The vibrational frequencies of the water molecules serve as a probe of the hydrogen bonding network, which is determined by the competition of solvent-anion and solvent-solvent interactions. The size dependence of the spectral features suggests the contribution of a second binding site for n>4, and the possibility of a temperature induced proton-transfer reaction for the n=4 cluster.

MG05 NEGATIVE ION PHOTOELECTRON SPECTROSCOPY OF SOLVENT-STABILIZED ANIONS

15 min

2:51

SHOUJUN XU, JOHN MICHAEL NILLES, WEIJUN ZHENG and KIT H. BOWEN, Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218. Solvent-stabilized anions of organic molecules, such as napthalene, pyrimidine, and pyridine, were investigated via negative ion photoelectron spectroscopy. In addition to determining the minimum number of solvent molecules needed to form a stable anion, we also determined that the excess charge was in each case located on the organic molecule and not on its solvent. By extrapolation, we determined the electron affinities of the bare organic molecules.

90

MG06 15 min A PHOTOELECTRON STUDY OF ANION-AROMATIC INTERACTIONS: A PROGRESS REPORT

3:08

JOHN MICHAEL NILLES, SHOUJUN XU, OWEN THOMAS, WEIJUN ZHENG and KIT H. BOWEN, Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218. Due to recent interest in the interactions of cations with aromatic systems, negative ion photoelectron spectroscopy was used to investigate the interaction of anions with several aromatic molecules. In coordination with Schlag, Weinkauf, et al., spectra were obtained for anion-molecule complexes of NO with the pi systems, Benzene, Napthalene, Pyridine, and Pyrimidine.

Intermission MG07 AUTODETACHMENT LIFETIMES OF SMALL DIANIONS

15 min

3:40

THOMAS SOMMERFELD, Theoretische Chemie, Universita¨ t Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany; FRANCESCO TARANTELLI, Dipartimento di Chimica, Universita` di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy. Almost all small dianions known from condensed phases are unstable with respect to electron autodetachment in the gas phase. These dianions show rare-gas-like closed-shell electronic ground states and represent a new type of metastable system. Here we discuss the ab initio calculation of energies and lifetimes of temporary closed-shell systems. Some methodological issues are briefly discussed, in particular, there is no “natural” choice of orbital set for metastable closedshell states and therefore no unique one-particle level. Applications to O2 , C22 , CN22 , and, CO23 are presented.

MG08

15 min

3:57

THE HF2 -H2 O COMPLEX: A THEORETICAL STUDY I.P. HAMILTON, BRANDON REINHART and G.P. LI, Department of Chemistry, Wilfrid Laurier University, Waterloo, Canada N2L 3C5. In the gas phase, HF2 is a hydrogen bonded species with a linear FHF geometry. The F-H distance is short and the hydrogen bond is strong. In the aqueous phase, it is known that the hydrogen bond in HF2 is weakened due to hydrogen bonding between HF2 and water molecules. We have examined the effect on the hydrogen bond in HF2 due to hydrogen bonding between HF2 and a single water molecule. For the HF2 -H2 O complex we have calculated geometries and vibrational frequencies for the equilibrium structure and several transition state structures. We find that the equilibrium structure is a mere 0.2 kcal/mole below the transition state structures indicating that the complex is highly fluctional. We further find that whereas the F-H distance increases for the F atom hydrogen bonded to H2 O, the other F-H distance decreases. The F-F distance is essentially unchanged and the linearity of the FHF geometry is strictly maintained.

91

MG09 15 min 4:14 USING PHOTOELECTRON AND ABSORPTION SPECTRA OF HYDRATED ELECTRON CLUSTERS TOGETHER TO BETTER UNDERSTAND THE ELECTRONIC PROPERTIES OF BULK WATER JAMES V. COE, Department of Chemistry, The Ohio State University, Columbus, OH 43210-1173. Photoelectron and absorption spectra of (H2 O)n clusters have been recorded by the Bowen Group at The Johns Hopkins University and the Johnson Group at Yale, respectively. It is interesting that all of the cluster spectra for both of these very different spectroscopies can be fit to the same empirical fitting function (Gaussian below peak center and Lorentzian above). Remarkably, the photoelectron and absorption spectra are almost identical in position and shape at n=11. The photoelectron and absorption sets slowly and smoothly separate as they grow towards bulk. While the absorption spectrum of the hydrated electron at bulk is well known, the extrapolation of the full photodetachment spectra to bulk is a new result. These results are evaluated in terms of a one electron model of the transition moment integral. Some of the consequences of these results for the electronic properties of bulk water will be discussed. MG10 15 min 4:31 THE CHANGE OF THE ELECTRONIC STRUCTURE OF METAL CLUSTERS UPON HYDROGEN CHEMISORPTION ¨ Fakult¨at f¨ur Physik, University ¨ S. BURKART, N. BLESSING, B. KLIPP, J. MULLER and G. GANTEFOR, of Konstanz, D-78457 Konstanz, Germany. The investigation of chemisorption on metal surfaces gives deep insight in catalytic processes and is important in technology. In cluster science a new variable appears. By varying the cluster size, the electronic and geometric structure of the particle changes. In addition, new building blocks for solid state materials consisting of such clusters can be designed. E.g. the neutral Al13 H cluster is highly symmetric and has a closed electronic shell. Its large HOMO-LUMO gap, similar to that of C60 , makes it to a promising canidate for a new cluster material. Here we report systematic studies of the change of the structure of size selected metal-clusters upon hydrogen chemisorption. The clusters are generated with a pulsed arc cluster ion source and hydrogen is mixed with the seeding gas. The anions are mass separated in a reflectron time-of-flight mass spectrometer. Electron spectra are recorded with a “magnetic bottle”-type time-of-flight electron spectrometer. First data on Aln Hm [1], Tin Hm [2] and Aun Hm are presented. [1] S. Burkart, N.Blessing, B. Klipp, J. Mu¨ ller, G. Gantef¨or, G. Seifert, Chem. Phys. Lett. 301 (1999) 546-550. [2] S. Burkart, N. Blessing, G. Gantefo¨ r, Phys. Rev. B 60, 23 (1999) 15639-15642 MG11 15 min 4:48 THEORETICAL STUDY OF THE SPECTROSCOPY AND DYNAMICS OF THE VINYLIDENE-ACETYLENE ISOMERIZATION ¨ HORST KOPPEL, RAINER SCHORK, Theoretical Chemistry, University of Heidelberg, INF 229, D-69120 Heidelberg, Germany. The results of a 5D ab initio quantum dynamical study of the vinylidene - acetylene isomerization reaction are presented. The study is based on a new ab initio potential energy surface for the planar system, obtained with the CCSD(T) method and the cc-pVTZ basis set. The dynamics is studied with grid methods, using 4-atom Jacobi-like coordinates and wave packet propagation techniques. The results of a 3D treatment, including the 2 angular degrees of freedom and the C-C stretching mode, have been reported earlier in the literaturea . Including all (planar) degrees of freedom, the experimental photodetachment spectrum of Lineberger and coworkersb is very well reproduced. Furthermore, lifetimes for broadband excitation and for individual vibrational levels of vinylidene have been computed, the latter with the aid of filter diagonalization techniques. The lifetimes are 2-3 orders of magnitude longer that previously believed, indicating a surprising stability of this reactive intermediate. Similar results have been obtained for the deuterated species, D2 CC supporting the above conclusions. a R. b K.

Schork, and H. K¨oppel, Theor. Chem. Acc. 100, 204 (1998). M. Ervin, J. Ho, and W. C. Lineberger, J. Chem. Phys. 91, 5974 (1989).

92

MH. MICROWAVE MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1015 McPHERSON LAB Chair: WOLFGANG JAEGER, University of Alberta, Edmonton, Canada

MH01 15 min 1:30 FOURIER TRANSFORM MICROWAVE DETECTION OF FREE RADICALS RELEVANT TO COMBUSTIONAND ATMOSPHERIC CHEMISTRY ¨ N. HANSEN, H. MADER, and F. TEMPS, Institut f¨ur Physikalische Chemie, Christian-Albrechts-Universita¨ t Kiel, Olshausenstr. 40, D-24098 Kiel, Germany. We report on first applications of a Laser Photolysis-Molecular Beam-Fourier Transform Microwave (LP-MB-FTMW) spectrometer in the spectral region 8 to 40 GHz, constructed for investigations of rotational spectra of free radicals. The experimental set-up consists of a near semi-confocal Fabry-Perot type microwave resonator mounted in a stainless steel vacuum chamber. The cavity resonance can be adjusted by moving the spherical mirror. A current actuated slit nozzle valve is situated near the center of the flat mirror, just above the microwave antennas. The performance of the spectrometer was optimized by recording SO (X3 ) microwave spectra. SO radicals were produced by 193 nm photodissociation of SO2 in a pulsed supersonic free jet expansion in Ar. Additionally, first results of the LP-MB-FTMW detection of the C2 H3 O (vinoxy) and of CF2 radicals will be presented.

MH02 15 min 1:47 NEW RESULTS FROM THE ROTATIONAL SPECTRA OF THE HALOGEN MONOXIDES. INTERATOMIC POTENTIALS, FINE AND HYPERFINE INTERACTIONS. B. J. DROUIN, E. A. COHEN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099; C. E. MILLER, Department of Chemistry, Haverford College, Haverford, PA 19041-1392; and ¨ H. S. P. MULLER, I. Physikalisches Institut, Universit¨at zu K¨oln, Z¨ulpicher Str. 77, D-50937, K¨oln, Germany. Last year we reported the IO rotational spectrum in vibrational levels up to v = 13 for the X1 2 3=2 state and to v = 9 for the X2 2 1=2 state. In comparison, previous studies of BrO were limited to v = 2 for X1 and v = 1 for the X2 state. Using the DC discharge cell that was so effective for vibrational excitation of IO, measurements of BrO have now been extended up to v = 8 and v = 7 for the X1 and X2 states, respectively. Excited vibrational levels of ClO were not obtained with these methods, however good signal to noise at thermal populations allowed measurements for the v = 2 levels of both the X1 and X2 states as well as 18 O in natural abundance. The Hamiltonian of Brown, et. al.a , with explicit isotope dependencies for each parameter, has provided a set of mass and nuclear moment independent parameters for each of the halogen monoxide species. The electron spin-rotation constant, , and the centrifugal distortion of the spin-orbit splitting, AD , which are normally correlated, have been separately determined by the isotope dependence of their contributions to the spectrum. Interatomic potentials have been derived from the mass-independent parameters that are accurate up to the observed excitation energies for each molecule. Analyses of the fine-structure parameters indicate that these molecules are close to the single perturber limit. The hyperfine parameters will be compared with the literature valuesb ; c ; d of the appropriate calculated relativistic radial integrals of the halogens. a J.

M. Brown and J. K. G. Watson, J. Mol. Spec. 148, 371 (1991). Pyykk¨o, M. Seth, Theor. Chem. Acc. 96, 92-104 (1997). c I. Lindgren and A. Ros´ en, Case Studies in Atomic Physics, 4, 197-298 (1974). d P. Pyykk¨ o and L. Wiesenfeld, Mol. Phys. 43, 557-580 (1981). b P.

93

MH03 THE ROTATIONAL SPECTRA OF THE X1

15 min 2

1=2 and X2

2:04

2

3=2 STATES OF BiO

EDWARD A. COHEN, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109-8099; DAMIAN M. GOODRIDGE and KENTAROU KAWAGUCHIa , Nobeyama Radio Observatory, Minamimaki, Minamisaku, Nagano 384-1305, Japan. BiO has a 2 r electronic ground state with a fine structure interval of  7087 cm 1 between the X1 and X2 states. In an extensive study of the BiO radical Shestakov, et al.b have determined spectroscopic constants for a total of nine of its electronic states. Their constants derived from the X2 2 3=2 ! X1 2 1=2 bands provided an excellent basis for a further investigation by microwave spectroscopy at Nobeyama Radio Observatory. BiO was produced in a flow system by heating Bi to 1120 K in a Knudsen cell and reacting the resulting vapor with an approximately 1:1 mixture of O2 and Ar in the presence of a dc discharge. A useful side effect of this method of production is the population of highly excited vibrational states of BiO. This is presumably due to collisional energy transfer from the metastable a1
g electronic state of O2 . As a result, transitions between vibrationally excited levels up to v = 9 in the X1 2 1=2 electronic state and v = 5 in the X2 2 3=2 state have been observed. Thus far, a total of 575 lines have been assigned and fitted using an effective Hamiltonian similar to that of Brown et al.c A merged fit of near infrared data for the X2 ! X1 ; 0–0 bandd with the rotational data has resulted in the determination of a very precise set of parameters for that band. There is excellent agreement between the optical and microwave parameters for all levels for which rotational spectra have been obtained. In addition, all of the principal hyperfine parameters for both the X1 and X2 states have been determined as well as their vibrational dependence. Only the magnetic hyperfine constant, d, has sufficient effect on the optical spectra to have been measured previously. These will be compared to those of related compounds and atomic Bi. a Present

address: Okayama University, Faculty of Science, Tsushimanaka 3-1-1, Okayama, 700-8530, Japan. Shestakov, R. Breidohr, H. Demes, K. D. Setzer and E. H. Fink J. Mol. Spectrosc. 190, 28-77 (1998) c J. M. Brown, E. A. Colbourn, J. K. G. Watson and F. D. Wayne, J. Mol. Spectrosc. 74, 294-318 (1979) d E. H. Fink, private communication. b O.

MH04 15 min 2:21 ELECTRIC DISCHARGE VS. EXCIMER LASER PHOTOLYSIS: A COMPARISON OF TWO METHODS USED TO PREPARE UNSTABLE MOLECULES FOR FOURIER TRANSFORM MICROWAVE SPECTROSCOPIC STUDY ´ ERIC ´ BETHANY BRUPBACHER-GATEHOUSE and FRED MERKT, Laboratorium f¨ur Physikalische Chemie, Eidgen¨ossische Technische Hochschule, ETH-Zentrum, CH-8092 Zu¨ rich, Switzerland. Although the use of an electric discharge has proved to be effective in the preparation of unstable species for spectroscopic study, this method has the disadvantage of being a “black magic” approach which completely lacks selectivity. If the molecule of interest happens to be prepared in a high enough yield that its spectrum is strong enough to be measured, then this technique has the advantage of being simple, relatively inexpensive, and easy to implement; however, if the spectra are weak or even un-observable because too few molecules are being generated, then the high selectivity of a laser photolysis preparation method is preferred. We are currently in the process of coupling an excimer laser to our existing pulsed jet cavity Fourier Transform microwave spectrometer with the hope that this will complement our electric discharge nozzle in allowing us to prepare unstable molecules, free radicals, and even ions for high resolution spectroscopic study. Details on some studies carried out using our electric discharge apparatus will be discussed, and a to-date report on the state of our experiments involving the excimer laser will be given.

94

MH05 MILLIMETER WAVE SPECTRA OF CHLORINE NITRATE

15 min

2:38

REBECCA A.H. BUTLER, Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, OH 43210; PAUL HELMINGER, Department of Physics and Chemistry, University of South Alabama, Mobile, AL 36688; FRANK C. DE LUCIA, Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, OH 43210. Chlorine nitrate is a planar, slightly asymmetric molecule of atmospheric interest. It has a dense rotational spectrum due to its relatively small rotational constants and its several low-lying vibrational modes. We have recorded this spectrum with a FASSST spectrometer over a range of 128-350 GHz, and will report on our analysis of many of these lower vibrational states, including 29 , 39 , 49 , 59 , 7 , 27 , 7 +9 , and 6 , taking into account several perturbations between states.

MH06 MILLIMETER WAVE, INFRARED AND AB INITIO STUDY OF FPS

15 min

2:55

¨ HELMUT BECKERS, HANS BURGER, PETER PAPLEWSKI, Anorganische Chemie, FB 9, Universit¨at¨ GH, D-42097, Wuppertal, Germany; JURGEN BREIDUNG, WALTER THIEL, Max-Planck-Institut f¨ur Kohlenforschung, D-45470 M¨ulheim an der Ruhr, Germany; MARCEL BOGEY, PASCAL DREAN and ADAM D. WALTERS, Physique des Lasers, Atomes et Mol´ecules, Centre d’Etudes et de Recherches Lasers et Applications, Universit´e des Sciences et Technologies de Lille, F-59655 Villeneuve d’Ascq, France. We show how a collaborative study involving ab initio calculations, chemistry, rovibrational spectroscopy and pure rotational spectroscopy can successfully be used to predict, produce, identify and characterize new short-lived molecular species. Ab-initio calculations at the MP2 and CCSD(T) level with VQZ1+ basis set were carried out using GAUSSIAN98 and MOLPRO98 programs in M¨uhlheim. FPS was produced by pyrolysis of F2 PSPF2 synthesized at Wuppertal and the rotationally resolved 1 band then identfied by FTIR spectroscopy. Accurate rotational and centrifugal distortion constants in the ground state were determined using millimeter wave spectroscopy in Lille. Measurements of the 34 S isotopomer and 3 vibrationally excited state will allow an experimental approximation to the equilibrium structure.

Intermission MH07 15 min 3:30 FEMTO-SECOND DEMODULATION AS A HIGH SPECTRAL PURITY SOURCE FOR THZ SPECTROSCOPY J. R. DEMERS, Department of Physics, The Ohio State University, 174 W. 18th Ave, Columbus, Ohio 432101106; T. M. GOYETTE, University of Massachusetts, Submillimeter Technology Lab, 175 Cabot Street, Lowell, Massachusetts, 01854; B. D. GUENTHER, Physics Department, Duke University, Durham, North Carolina, 27708-0305; F. C. DE LUCIA, Department of Physics, The Ohio State University, 174 W. 18th Ave, Columbus, Ohio 43210-1106. A Low Temperature Grown GaAs Photo-conductive Switch (LTG GaAs PCS) is employed to demodulate femtosecond pulses from a mode-locked Ti:sapphire laser. The resulting radiation contains all the high spectral purity Fourier components of the original pulse train. A specific model for the system noise and spectral purity will be presented. System dependence upon laser repetition rate will be discussed along with the results from passively increasing the repetition rate. Doppler limited, rotational spectra will be presented.

95

MH08 15 min 3:47 QUASI-MICROWAVE SPECTROSCOPY OF NON-POLAR DIATOMIC MOLECULE BY USING OPTICAL PHASELOCKED LASERS. MOTOHIRO KUMAGAI, HIDETO KANAMORI, Tokyo Institute of Technology, Department of Applied Physics, Ohokayama, Meguro-ku, Tokyo, Japan; MICHIO MATSUSHITA, TATSUHISA KATO, Institute for Molecular Science, Okazaki, Japan. A new type optical-optical double resonance (OODR) experiment was developed by using phase controlled light source. The difference frequency between two single-mode lasers was stabilized to a MW frequency synthesizer by using an optical phase-lock loop. The difference frequency can be continuously scanned from 0.1 to 18GHz. This system was applied to the B 1 u -X 1 g + transitions of Cs2 molecule. Double resonance signals corresponding to the rotational transitions of the ground state or the excited state are measured in sub-Doppler condition and those frequencies are determined as accurate as MW spectroscopy. Furthermore heterodyne detection makes it possible to measure the real and imaginary part of the third order susceptibility of the B-X transition at the same time. This means we can detect the phase of the polarization in the molecular system coherently generated by the phase-locked two lasers.

MH09 THE RADIO SPECTRA OF SICCH, SICN AND SiNC

15 min

4:04

A. J. APPONI, M. C. MCCARTHY, C. A. GOTTLIEB, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138.. Three new silicon-bearing radicals of astrophysical interest, SiCCH, SiCN and SiNC, were detected in a laboratory discharge in their X 2  ground states by Fourier transform microwave and direct absorption millimeter-wave spectroscopy. Well-resolved –doubling was observed in both fine structure components, and hyperfine structure was observed in the low rotational transitions of the 2 1=2 ladder. With the spectroscopic constants derived from the laboratory measurements, the spectra of the three radicals can be calculated to an uncertainty of less than 0:1 km s 1 in equivalent radial velocity over the entire range of interest to radio astronomers. SiCN with a dipole moment of 2.9 D is probably the most promising of the three for astronomical discovery.

MH10 LABORATORY DETECTION OF HC6 N

15 min

4:21

V. D. GORDON, M. C. McCARTHY, A. J. APPONI, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 and Division of Engineering & Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138. A linear triplet isomer of HC6 N has been detected in a supersonic molecular beam by Fourier transform microwave spectroscopy. A total of 85 hyperfine components from six rotational transitions between 8 and 18 GHz were measured to an uncertainty of 5 kHz; a similar set of transitions were detected for the 15 N isotopic species, produced using an isotopically enriched precursor gas sample. The spectroscopic constants for both species, including the fine and hyperfine coupling constants, were determined to very high accuracy, and these allow calculation of the entire radio spectrum to a fraction of 1 km s 1 in equivalent radial velocity. Triplet HC6 N is a highly polar, low-lying isomer; measurements show it to be about ten times more abundant than a ring-chain isomer recently detected with the same spectrometer, which may indicate that it is the lower-energy isomer, contrary to previous calculations.

96

MH11 10 min MILLIMETER-WAVE SPECTROSCOPY AND COUPLED CLUSTER CALCULATIONS FOR NCCP

4:38

L. BIZZOCCHI, C. D. ESPOSTI, Dipartimento di Chimica “D. Ciamician”, Universit`a di Bologna, Via F. Selmi 2, I-40126 Bologna, Italy; P. BOTSCHWINA and B. SCHULZ, Institut f¨ur Physikalische Chemie, Universit¨at G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany.

MH12 LABORATORY DETECTION OF TWELVE CARBON-SULFUR CHAINS

15 min

4:50

V. D. GORDON, M. C. McCARTHY, A. J. APPONI, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 and Division of Engineering & Applied Sciences, Harvard University, 29 Oxford St., Cambridge, MA 02138. Twelve sulfur-containing carbon chains have recently been detected and spectroscopically characterized in our laboratory by Fourier transform microwave spectroscopy. These include: the singlet chains C7 S and C9 S; the triplet chains C6 S and C8 S; the free radicals HC5 S, HC6 S, HC7 S, and HC8 S; and the asymmetric tops H2 C4 S, H2 C5 S, H2 C6 S, and H2 C7 S. In addition, all three fine structure ladders of triplet C4 S have now been observed, and the two fine-structure constants and  determined to high accuracy. An experimental structure of C5 S has also been derived on the basis of the singly-substituted isotopic species which were observed in natural abundance. A summary of these and other recent results will be presented. MH13 Post-deadline Abstract 10 min 5:07 THE CHARACTERIZATION OF HYPERFINE EFFECTS IN YTTERBIUM HALIDE DIATOMIC MOLECULES USING MWFT SPECTROSCOPY CAMERON S. DICKINSON, Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, CANADA; NICHOLAS R. WALKER, Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, CANADA; JOHN A. COXON, Department of Chemistry, Dalhousie University, Halifax, Nova Scotia, B3H 4J3, CANADA; MICHAEL C. L. GERRY, Department of Chemistry, University of British Columbia, Vancouver, British Columbia, V6T 1Z1, CANADA. The Ytterbium atom is isovalent with the alkaline earth metals by virtue of its 4f14 6s2 ground state configuration. Data obtained from studies on diatomic molecules containing Yb therefore provide appropriate parameters for comparison with alkaline earth metal analogs. In this work, the microwave spectra of YbBr, YbCl and YbF have been assigned for the 2 + , v = 0 ground state. Precise rotational constants and several hyperfine parameters have been obtained. In addition, studies of the v = 1 levels for the most abundant isotopomers of YbF and YbCl have provided equilibrium bond lengths and a measure of the vibrational dependence for each of the fitted parameters. The determined hyperfine constants have been used to provide information about the electronic structures of the molecules.

97

MI. ELECTRONIC (LARGE) MONDAY, JUNE 12, 2000 – 1:30 PM Room: 1005 SMITH LAB Chair: MARTIN GRUEBELE, University of Illinois, Urbana, IL

MI01 15 min DETERMINATION OF EXCITED STATE DIPOLE MOMENTS OF GAS PHASE MOLECULES. PART I a

1:30

TIMOTHY M. KORTER, CHRISTOPHER J. BUTLER, DAVID R. BORST, and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260. The measurement of molecular dipole moments has always been of great interest to chemists. While microwave spectroscopy has long used the Stark effect to determine the ground state dipole moments of gas phase molecules, there is considerably less data available for electronically excited molecules. These excited state dipole moments can be measured by rotationally resolved S1 S0 fluorescence excitation spectroscopy of gas phase molecules in an electric field. This talk will detail the experimental apparatus used to obtain such spectra and the procedure for their analysis. Modelling of the Stark effect on the rotational energy levels is done by expanding the original zero-field Hamiltonian to include field interacting terms as well as removal of the M state degeneracy. A diagonalization of the complete energy matrix is then performed to obtain eigenvalues (frequencies) and eigenvectors (intensities). This spectroscopic technique is extremely sensitive to both the change in magnitude and change in orientation of the dipole moment upon electronic excitation. a Work

supported by NSF.

MI02 15 min DETERMINATION OF EXCITED STATE DIPOLE MOMENTS OF GAS PHASE MOLECULES. PART II a

1:47

TIMOTHY M. KORTER and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260. The rotationally resolved S1 S0 fluorescence excitation spectra of aniline, phenol, styrene, and indole have been obtained in the presence of an external electric field. The Stark effect on the rotational energy level structure allows us to accurately determine the values for the different components of the dipole moment vector in the S1 electronic state. Electronic excitation can have a considerable effect upon the dipole moment magnitude. An example is aniline, where in S0 , a = 1.129 D and in S1 , a = 2.796 D. The large increase in the dipole moment is a result of changes in the electron distribution near the nitrogen upon absorption of an ultraviolet photon. Time permitting, preliminary results on molecular clusters will also be presented. a Work

supported by NSF.

98

MI03 15 min 2:04 DIRECT DETERMINATION OF MOLECULAR CONSTANTS FROM ROVIBRONIC SPECTRA WITH GENETIC ALGORITHMS W. LEO MEERTS, Department of Molecular and Laser Physics, University of Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands; J. A. HAGEMAN, R. WEHRENS, L. M. C. BUYDENS, Laboratory of Analytical Chemistry, University of Nijmegen; and R. DE GELDER, Department of Inorganic Chemistry, University of Nijmegen. Recently, attempts to automate the interpretation of rovibronic spectra have been undertaken. Automation becomes increasingly important when spectra become more difficult to interpret and/or pre-knowledge about the molecule is little or lacking. The group of Neussera used a procedure which directly fits the experimental data, without any preceding assignment of lines, with the help of the so called correlation automated rotational fitting algorithm. This algorithm still relies on accurate initial estimates of the rotational constants obtained from other experiments. Unfortunately, the method still has limited applicability. The approach of fine-tuning the parameters of the Hamiltonian model so that the theoretical spectrum is in close agreement with the experimental one, can be seen as an optimisation problem. The process of determining molecular constants can be automated with global optimisation methods like Simulated Annealing (SA), Tabu Search (TS) or Genetic Algorithms (GA’s). In this paper it is shown that a GA with a specially developed fitness function is very successful in directly determining the molecular constants from LIF spectra. This is done without using any initial estimates of these constants, except their global limits. This new approach is demonstrated for 4 rotationally resolved (LIF) spectra from indole, indazole, imidazole and 4-aminobenzonitril (4-ABN). The spectra were measured by Berden et al.b In addition, the robustness of this GA-based method has been assessed by artificially deteriorating the quality of the data. It will be shown that the method is quite robust and, therefore, widely applicable. a R.M. b G.

Helm, H.-P. Vogel and H.J. Neusser, Chem. Phys. Lett. 270, 185 (1997). Berden, W.L. Meerts and E.J. Jalviste, J. Chem. Phys. 103, 9596 (1995).

MI04 15 min 2:21 A NEW LOOK AT A CHIRAL PROTOTYPE: ROTATIONALLY RESOLVED MW AND UV SPECTRA OF JETCOOLED 1,1’-BI-2-HYDROXYNAPHTHALENE S. DAVIS, D. F. PLUSQUELLIC and R. D. SUENRAM, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899. Recent efforts towards characterization of biologically relevant molecules exploiting rotationally resolved gas phase spectra will be reported. The experimental techniques for i) generating sufficient densities of supersonically cooled molecules with high melting points (T>200C) and ii) obtaining rotational resolution of large aromatic system having >20 heavy atoms will be presented. The low resolution (1cm 1 ) UV spectrum of structurally chiral 1,1’-bi-2-hydroxynaphthalene has been obtained. The LIF spectrum near 342 nm reveals the presence of two prominant features separated by 50 cm 1 . This splitting is tentatively interperted in terms of an exciton interaction arising from the proximity of the two naphthol subunits. The results of ongoing efforts to obtain the rotationally resolved spectra, which are expected to further validate this interpertation, will be discussed. Furthermore, the rotational constants obtained from both MW and UV studies will provide detailed structural information. In particular, the dihedral angle defining the out-of-plane orientation between the two naphthol ring systems, which gives rise to the chiral nature and therefore the degree of optical activity, will be accurately determined. Additionally, relationships between the experimental results and theoretical predictions will also be discussed.

99

MI05 15 min 2:38 OPTICAL-OPTICAL DOUBLE RESONANCE AND CAVITY RING-DOWN STUDIES ON THIOPHOSGENE DAVID C. MOULE, Department of Chemistry, Brock University, St Catharines, ON, L2S3A1; EDWARD C. LIM and HAISHENG LIU, Department of Chemistry, Knight Chemical Laboratory, University of Akron, Akron, OH, 44325-3601; and RICHARD H. JUDGE, Department of Chemistry, University of Wisconsin-Parkside, Kenosha, WI 53141-2000. The first triplet electronic state of thiophosgene, Cl2 CS, has been studied by cavity ring-down absorption and OODR pump-probe methods. Under pulse amplified ring-laser conditions the OODR spectrum displays a simple yet unexpected line structure. Our analyses suggests that these lines can be attributed to the J=0 and J=1 rotational levels of the triplet state that do not undergo a rapid intersystem crossing to the high vibrational levels of the singlet ground electronic state.

MI06 15 min 2:55 FRANCK–CONDON SPECTRAL CALCULATION ON TRANS–HYDROQUIONE USING CORRELATION FUNCTION APPROACH SANJAY WATEGAONKAR, G. NARESH PATWARI, Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, India 400 004.; M. DURGA PRASAD, School of Chemistry, University of Hyderabad, Hyderabad, India 500 046.. IVR in polyatomic molecules has been found to be extremely fast even at energies as low as a few hundred wavenumbers. In order to understand the IVR dynamics better one can proceed to calculate the fluorescence spectra and compare with the experimental data. However, for polyatomic molecules with large number of vibrational modes even calculating a simple Franck–Condon spectrum is not a simple task. As a first step towards this we have calculated the excitation and dispersed fluorescence spectra of hydroquinone, ab initio, using a correlation function approach using a quadratic Hamiltonian. Time dependent coupled cluster method was used to propogate the wavefunction in time. The comparison between the calculated and experimental spectra will be presented and the validity of the method will be discussed vis–´a–vis the observed IVR behaviour.

Intermission

100

MI07 SPECTROSCOPIC INVESTIGATION AND HYDROXYCOUMARIN DYE IN SOLGEL

PREDICTION

OF

LASER

ACTION

15 min 3:30 PROPERTIES OF 4-

ASMA SOHAIL FAROOQUI and Z. H. ZAIDI, Department of Physics, Jamia Millia Islamia, Jamia Nagar, New Delhi 110025 India. Out of thousands of organic dyes synthesized over the last hundred years only a few show laser action when excited by Qswitched laser or a pulsed nitrogen laser and still fewer under flash lamp excitation. Organic dyes that show laser action are selected by trial and error. For an efficient working of a laser material it is important to select dyes which have high quantum yield and low lasing threshold. Coumarins or -benzopyrones are known for their strong lasing effect. It is a class of laser dyes emitting in the blue green region of the spectrum and derived from coumarin - the parent molecule on substitution with auxochromic (OH, NH2, CH3, etc.) groups at various carbon positions. Depending on the location and direction of the singlet-singlet (S-S) relative to triplet- triplet (T-T) oscillators within the molecular frame, substitution by the hydroxy auxochromic group may cause T-T absorption bands to move in or out of fluorescence region, or they may be left unchanged. An attempt is made to study the spectroscopic characteristics of 4-hydroxycoumarin molecule. Electronic absorption spectra of 4-hydroxycoumarin are measured in the wavelength region 200 700 nm in liquid solvents and solgel. Fluorescence spectrum is measured on exciting 4-hydroxycoumarin doped in solgel by varying the excitation wavelengths. Electronic transitions observed experimentally, are interpreted using the optimized geometries and CNDO/S-CI method. Assignments of observed electronic transitions are made on the basis of singlet- triplet electronic transitions. Further, effect of hydroxy substituent on the spectral properties of the parent aromatic molecule are investigated on the basis of molecular structure and spectral predictions for 4-hydroxycoumarin as a potential dye laser material are made. These predictions supported by theoretical results are presented graphically with possible arrangements of low energy S-S oscillators relative to T-T oscillators located in the fluorescence region. Depending on short or long axis substitution, the redshifts of the S-S and T-T absorption bands are observed and the importance of these red shifts, as related to the laser action properties are discussed. We found a good agreement between the experimental and calculated results. Further more, 4-hydroxy coumarin doped in solgel is found to be a potential dye laser material. MI08 HIGH RESOLUTION STUDY OF THE CONFORMERS OF 3-AMINOPHENOL. a

15 min

3:47

JENNIFER A. BARTELS, BRIAN BLASIOLE, TIMOTHY M. KORTER, and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. Extensive study of monosubstituted aromatic rings like phenol and aniline has prompted the investigation of molecules containing two different substituents, such as the aminophenols. The vibrationally resolved S1 S0 electronic spectrum of 3-aminophenol exhibits two origin bands, separated by 353 cm 1 . A spectrum of each origin band was recorded at full rotational resolution. Analyses of these spectra show that the bands correspond to the cis and trans conformers of 3aminophenol. Evidence for the identification of the conformers, which differ only in the position of the hydroxy hydrogen atom, will be discussed. a Work

supported by NSF.

MI09 15 min 4:04 ROTATIONALLY RESOLVED FLUORESCENCE EXCITATION SPECTROSCOPY OF BENZYL ALCOHOL .a ALEXEI NIKOLAEV and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. Benzyl alcohol has been the subject of many spectroscopic investigations in the gas phase, including REMPI, IR-UV double resonance and UV band contour analysis. However, ambiguities exist regarding the nature of the observed transitions and the true gas phase structure of the isolated molecule. In this paper, attempt will be made to clarify these issues by means of rotationally resolved laser induced fluorescence spectroscopy of benzyl alcohol and its deuterated analog. a Work

supported by NSF

101

MI10 15 min 4:21 THE EFFECT OF KINEMATIC FACTORS ON ROTATIONALLY AND ROVIBRATIONALLY INELASTIC SCATTERING OF GLYOXAL MARIANA D. DUCA, CHARLES S. PARMENTER, Indiana University Department of Chemistry, Bloomington, Indiana 47405; SAMUEL M. CLEGG, Department of Geophysical Sciences, The University of Chicago, Chicago, Illinois 60637. State-to-state rotationally and rovibrationally inelastic scattering of S1 00 , K0 = 0 trans-glyoxal has been shown to be controlled by the kinematics of the collision. More details of this kinematic effect have been extracted from new glyoxal + H2 , D2 , He and Ne scattering experiments under well defined center-of-mass collision energies (Ec:m: ) and momenta (pc:m: ). The experiment couples a laser pump-dispersed fluorescence probe approach with crossed molecular beams. The relative velocity (vrel ) of the collision pair was tuned by adjusting the beam intersection angle so as to select the desired pc:m: or Ec:m: . The distributions of relative rotational and rovibrational cross sections have an exponential dependance on the angular momentum change for all values of kinematic parameters. The slopes of these dependencies have a welldefined trend as a function of pc:m: regardless of the target gas identity. In contrast, analogous plots against vrel or Ec:m: tend to be unique for each target gas. This behavior suggests that the momentum is the most convenient kinematic factor for discussing the cross section distributions.

MI11 15 min 4:38 ABSOLUTE CROSS SECTIONS FOR VIBRATIONAL ENERGY TRANSFER IN THE QUASI-CONTINUUM OF PARA-DIFLUOROBENZENE. UROS S. TASIC, TODD A. STONE, and CHARLES S. PARMENTER, Indiana University Department of Chemistry, Bloomington, Indiana 47405. These experiments yield basic information for kinetic models of the activation/deactivation step of thermal unimolecular reactions. For these highly excited vibrational levels where the high state density approaches a quasi-continuum and where state mixing is significant, a special technique based on oxygen fluorescence quenching (chemical timing)a is used. Absolute cross sections are measured for vibrational energy transfer (VET) from a wide range of S1 levels of paradifluorobenzene (pDFB) as it undergoes single collisions with rare gases. The highest region so far studied has densities of about 104 levels per cm 1 . The study involves preparing pDFB in a narrow vibrational region and monitoring fluorescence as VET with Ar occurs into a field of surrounding vibrational levels. All of the cross sections so far observed are less than the Lennard-Jones value that is often assumed for modeling the unimolecular problem. Some exceed hard sphere values. a R.

A. Coveleskie, D. A. Dolson, and C. S. Parmenter, J. Phys. Chem., 89, 645 (1985).

MI12 STUDYING THE DYNAMICS OF THE RING-OPENING REACTION OF 1; 3

15 min CYCLOHEXADIENE

4:55

RAY DUDEK, CONOR EVANS, PETER WEBER, Department of Chemistry, Brown University, Providence, RI 02906. Upon excitation by an ultra-violet photon 1; 3 Cyclohexadiene loses its cyclic structure and becomes one of the isomers of 1; 3; 5 hexatriene. This ring-opening reaction serves as a model for a large number of photochemical processes. While many detailed studies have shed considerable light on this reaction, many details of the reaction pathway through the excited electronic states still have not yet been well determined. We have studied the ring-opening reaction using fluorescence spectroscopy and obtained the first free jet fluorescence spectrum. The spectrum provides clues about the excited states populated upon excitation. We have also examined the reaction process using pump-probe gas-phase electron diffraction. This technique gives a direct picture of the excited state structures accessed during the reaction. Preliminary results will be presented.

102

MI13 Post-deadline Abstract 15 min 5:12 TEMPERATURE DEPENDENCE OF THE RADIATIVE LIFETIME OF J-AGGREGATES WITH DAVYDOV SPLITTING OF THE EXCITATION BAND I. G. SCHEBLYKIN, M. M. BATAIEV and A. G. VITUKHNOVSKY, Lebedev Physical Institute, RAS, Leninsky pr.,53, 117924 Moscow, Russian Federation; M. VAN DER AUWERAER, Laboratory for molecular Dynamics and Spectroscopy, K.U.Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium. The temperature dependence of the radiative exciton lifetime (rad ) of J-aggregates of 3,30 -bis(sulffopropyl)-5,50 -dichloro9-ethylthiacarbocyanine (THIATS) characterized by a Davydov splitting of the exciton band has been determined over the temperature range from 4.2 to 130K.a The Davydov splitting of the exciton was taken into account during the calculation of the coherent length (NC ) from the values of (rad ). The dependence of (rad ) on temperature was analyzed. The rad (T) of J- aggregates of THIATS can be rationalized within the framework of a 1-D excitation model. a I.G.

Scheblykin, M.M. Bataiev, M. Van der Auweraer, A.G. Vitukhnovsky, Chem. Phys. Lett. 316, 37-44(2000)

103

TA. ELECTRONIC (SMALL) TUESDAY, JUNE 13, 2000 – 8:30 AM Room: 1153 SMITH LAB Chair: CHRIS BALL, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA

TA01 15 min 8:30 TERM ENERGIES, LINE POSITIONS, AND SPECTROSCOPIC CONSTANTS FOR THE OH MEINEL BAND SYSTEM P. C. COSBY, T. G. SLANGER, D. L. HUESTIS, Molecular Physics Laboratory, SRI International, Menlo Park, CA 94025; D. E. OSTERBROCK, University of California Observatories/Lick Observatory, University of California, Santa Cruz, CA 95064. High resolution spectra of OH Meinel bands emitting in the region of 571-993 nm have been observed in spectra of the night sky using the HIRES echelle spectrograph on the Keck I telescope on Mauna Kea, HI. Line positions in the 6-1 and other bands, measured with an accuracy of 0.01 cm 1 , are in excellent agreement with line positions calculated from the molecular constants of Abrams et ala and listed in the HITRAN data baseb for lines measured in the main branches with J < 10.5. However, for transitions accessing higher rotational levels in the main branches, or any rotational levels in the satellite branches, substantial discrepancies, up to 0.14 cm 1 , are found between the observed lines and their positions expected from these data bases. In an effort to determine the source of these discrepancies, the 1696 reported line positions of the 23 Meinel bands measured by Abrams et al were subjected to a model-free least-squares fit to determine experimental term energies for OH X(v=0-10). With few exceptions, those line positions are found to be exceptionally precise, yielding a standard deviation in the fit of 0.001 cm 1 . Referenced to the accurate term energies of Melen et alc for v=0-3, the experimental line positions of Abrams et al yield term energies for v=4-10 that are consistent with the present observations and with the term energies of Coxond but not with the calculated term energies reported by Abrams et al, or with those used to generate the HITRAN transitions for v > 3. Molecular constants for the X 2  state are also determined from the line positions of Abrams et al which reproduce both the experimental term values and the present Meinel observations, and are consistent with the rotational constants calculated from the X 2  potential energy curve. a M.

C. Abrams, S. P. Davis, M.L.P. Rao, R. Engleman, and J. W. Brault, Ap. J. Suppl. 93, 351 (1994). Goldman, W. G. Schoenfeld, D. Goorvitch, C. Chackerian, H. Dothe, F. Melen, M. C. Abrams, and J.E.A. Selby, J. Quant. Spectrosc. Radiat. Transfer 59, 453 (1998). c F. Melen, A. J. Sauval, N. Grevesse, C. B. Farmer, Ch. Servais, L. Delbouille, and G. Roland, J. Mol. Spectrosc. 174, 490 (1995). d J. A. Coxon, Can. J. Phys. 58, 933 (1980); Can. J. Phys. 60, 41 (1982). b A.

TA02 LINEAR RYDBERG STATES OF WATER

15 min

8:47

W. L. GLAB and T. THOMPSON, Texas Tech University, Lubbock, TX, 79409. We have studied the spectrum of the water molecule above the ionization limit using resonant excitation through a linear intermediate state. Water vapor in a differentially pumped time-of-flight mass spectrometer was excited to the energy region above the first ionization limit using a stepwise resonant (1+1’) REMPI process, in which intense VUV light near 118.5 nm pumped selected rotational levels of the (A~2 A1 )3pb12 B2 linear electronic state, followed by further excitation by a scanning dye laser. We observed transitions to Rydberg states which we have tentatively identified as belonging primarily to linear states converging to the A~2 A1 electronic state of the ion. These electronically autoionizing states perturb the bent Rydberg states which we have studied previously.

104

TA03 DISPERSED FLUORESCENCE SPECTRA OF SIMPLE CARBENES

10 min

9:04

BOR-CHEN CHANG, Department of Chemistry, National Central University, Chung-Li 32054, Taiwan; ANDREW J. BEZANT and TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, 120 W. 18th Avenue, Columbus, Ohio 43210. The electronic excitation specta of simple carbenes such as CCl2 , HCCl, and HCBr were found to be complicated due to Renner-Teller effects, spin-orbit couplings, and Fermi resonances.a Information on the ground electronic state structure is crucial to unravel the interplay between these interactions, as well as being valuable in its own right. We have adopted the combination of a DC electrical discharge free jet source and laser-induced fluorescence (LIF) to record the dispersed fluorescence spectra of these simple carbenes. The dispersed fluorescence spectra of CCl 2 reveal the vibrational structure ˜ state. Comparison with previous data from cryogenic matrix workb and recent theoretical calculationsc will be of the X discussed. Progress on the dispersed fluorescence experiments of other carbenes, such as HCBr and HCCl, will also be presented. Acknowledgments: BCC thanks Dr. Kopin Liu (Academia Sinica, Taiwan) for help with the experiment and the National Science Council, Taiwan for its support of this work under Grant No. NSC88-2113-M-008-007. J. Clouthier and J. Karolczak, J. Chem. Phys. 94, 1 (1991). E. Bondybey, J. Mol. Spectrosc. 64, 180 (1977). c K. Sendt and G. B. Bacskay, J. Chem. Phys. 112, 2227 (2000).

a D. b V.

TA04 15 min NEAR-INFRARED LASER SPECTROSCOPY OF BROMOMETHYLENE IN A SLIT JET EXPANSION

9:16

BOR-CHEN CHANG, Department of Chemistry, National Central University, Chung-Li 32054, Taiwan; MATHEW COSTEN, ANDREW J. MARR, GRANT RITCHIE, GREGORY E. HALL and TREVOR J. SEARS, Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000. Near-infrared transient frequency-modulation spectroscopy has been combined with a slit jet expansion-cooled source to ˜ 1 A0 electronic transition origin in ˜ 1 A00 X acquire the high resolution spectrum of the bromomethylene (HCBr/DCBr) A 1 the vicinity of 11972cm . The radical was generated by 193nm laser photolysis of bromoform in the early stages of the jet expansion and several rotational subbands were recorded. The jet-cooled spectrum shows a rotational temperature of approximately 20K. The spectral simplication achieved by jet cooling allowed a nearly complete analysis. The analysis of the data combined with results from previous measurements at ambient temperature has determined the ground state rotational constants and structure. It also shows that except for the K 0 =0 stack, the electronic excited state is highly perturbed by Renner-Teller and anharmonic couplings. Details of the experiment and analysis will be presented. Acknowledgments: The experimental work was carried out at Brookhaven National Laboratory under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences. BCC also thanks the National Science Council, Taiwan for its support of this work under Grant No. NSC89-2113-M-008004.

105

TA05 15 min VIBRATIONALLY EXCITED BROMOMETHYLENE-MAPPING THE BENDING POTENTIAL SURFACE

9:33

TREVOR J. SEARS, ANDREW J. MARR, Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000; NILS HANSEN, Physical Chemistry Department, Christian-AlbrechtsUniversitaet Kiel, Olshausenstrasse 40-60, 24106 Kiel. A wealth of high resolution data have now been obtained for HCBr and its deuterated isotopomer. Many vibronic bands have been rotationally analyzed and bending vibronic levels in the ground and first excited singlet states have been identified. The rotational levels in all the ground state vibrational levels so far studied at high resolution are regular and show no perturbations. This includes the (020) level of HCBr at 2311cm 1 which is above previously predicted positions of the low-lying triplet state. The bending vibrational spacings in the ground state do show some peculiarities, however. In the excited state, levels with K = 0 exhibit few, localized, perturbations, while those with K ¿ 0 are generally strongly perturbed. The measured vibronic levels should allow the determination of the Renner-Teller coupled bending potential surfaces and progress in this direction will be reported. Acknowledgments: This work was carried out at Brookhaven National Laboratory under Contract No. DE-AC0298CH10886 with the U.S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences.

TA06 BROMINE-CONTAINING RADICALS FORMED ON PHOTOLYSIS OF CHBr3

15 min

9:50

NILS HANSEN, Physical Chemistry Department, Christian-Albrechts-Universitaet Kiel, Olshausenstrasse 40-60, 24106 Kiel; ANDREW J. MARR and TREVOR J. SEARS, Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000. The photolysis of bromoform at 193 nm is thought to proceed via a primary HCBr2 radical product that undergoes spontaneous secondary decomposition leading to HCBr and CBr in separate channels. Spectra of both these secondary radicals have been detected in the past. During the measurement of a vibrational hot band of HCBr near 1m, several bands of yet another radical species were identified. Chemical tests showed that the new species contained no hydrogen and the observed isotope structure indicated that there was just one bromine atom. Rotational analysis of the bands resulted in estimated rotational constants close to 0.24cm 1 for a linear species, consistent with the CCBr radical. This must be produced by secondary radical reactions, possibly via dibromoacetylene formed on recombination of CBr. We have found no previous references to the spectrum of this species, which by analogy with CCH is expected to possess low-lying 2  and 2  electronic states. This paper will describe the observed spectra and progress in their assignment. Acknowledgments: The experimental work was carried out at Brookhaven National Laboratory under Contract No. DEAC02-98CH10886 with the U.S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences.

Intermission

106

TA07 SINGLET TRANSITIONS OF METHYLENE AT 890 nm

15 min

10:20

KAORI KOBAYASHI, Department of Chemistry, Brookhaven National Laboratory, Upton, New York 119735000; LEAH D. PRIDE, ERULF Student at the Department of Chemistry, Brookhaven National Laboratory. Present address: Department of Chemical Technology, New York City Technical College, Brooklyn, NY 11201; and TREVOR J. SEARS , Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973-5000. The near-infrared spectrum of CH2 (b˜ 1 B1 - a˜ 1 A1 ) was observed using frequency-modulated diode laser absorption spectroscopy. Rovibronic transitions between 11038 cm 1 and 11370 cm 1 were assigned based on the known lower state combination differences. On the basis of comparison with published results of quantum chemical calculations including the Renner-Teller effect, three upper rovibronic levels were assigned possessing both a˜ and b˜ primary electronic wavefunc˜ ˜ tion character: K = 1 b(0,2,0), K = 1 a˜ (1,7,0), and K = 4 b(0,2,0). Transitions involving J as high as 8 were observed in K = ˜ 1 b(0,2,0). In addition to further characterizing the CH2 bending potential surfaces near the barrier to linearity, the analysis also extends the rotational number of ground state levels that are accurately known. Acknowledgments: This work was at Brookhaven National Laboratory carried out under Contract No. DE-AC0298CH10886 with the U.S. Department of Energy and supported by its Division of Chemical Sciences, Office of Basic Energy Sciences. TA08

15 min

10:37

˜ 3 i STATE VIBRONIC STRUCTURE OF THE CCS RADICAL IN THE A MASAKAZU NAKAJIMA, YOSHIHIRO SUMIYOSHI and YASUKI ENDO, Depertment of Pure and Applied Sciences, College of Art and Sciences, The University of Tokyo, 153-8902, Tokyo, Japan. The CCS radical was generated in a supersonic jet using a pulsed-discharge of a mixture gas: C2 H2 0.35%/CS2 0.35% in Ar. Ro-vibronic spectra of the radical were measured with a LIF spectroscopic method in a spectral region from 900 to 600 ˜ 3  transition. In the near infrared region where a photomultiplier has no sensitivity, ˜ 3 i – X nm, corresponding to the A an MODR technique using an FTMW spectrometer was employed. ˜ ˜ v1 10) – X(000) ˜ ˜ v1 00) – X(000) and A( transitions (v1 = 1, 2). For Some of the observed bands could be assigned to the A( ˜ v1 00) level, rotational constants were determined using a 3  Hamiltonian. Although the A ˜ 3 i (v1 10) vibronic level the A( splits into seven levels by the Renner-Teller interaction, transitions to only two of the seven levels from the ground state ˜ v1 10) level, the spin-orbit constant, and the position of the were observed. Using the two transition frequencies of the A( ˜ state are estimated ˜ v1 00) level, the Renner parameter jj and the harmonic frequency of the bending motion !2 in the A A( to be 0.235 and 402.39 cm 1 , respectively. TA09 SEP SPECTROSCOPY OF THE HCCS RADICAL

15 min

10:54

TOMOKO ISHIBASHI, YOSHIHIRO SUMIYOSHI and YASUKI ENDO, Department of Basic Sciences, Graduate School of Arts and Sciences, University of Tokyo. Stimulated Emission Pumping (SEP) spectroscopy has been applied to the study of the ground state vibronic structure of a linear tetra-atomic free radical, HCCS, which has two Renner-Teller active bending modes. The radical was produced in a supersonic jet by a pulsed discharge in a C2 H2 and CS2 mixture diluted in Ar. Two Nd YAG laser pumped dye lasers with linewidths 0.02 cm 1 are used to observe SEP spectra. Eight vibronic bands in the ground electronic states were observed from the 2 3=2 origin band excitation, and 4 bands from the 2 1=2 origin band excitation. Three of the observed bands are assigned to the CS stretching mode, and others to overtones and combinations of two bending modes with  vibronic symmetry. The observed vibronic energy levels are successfully analyzed by taking into accunt the Renner-Teller interaction including the cross vibronic terms. The determined parameters agree with previous ab initio calculationsa and mm-wave spectroscopyb . a P. b J.

G .Szalay, J. Chem. Phys., 105, 2735 (1996), Y. Li and S. Iwata, Chem. Phys. Lett., 273, 91 (1997). Tang and S. Saito, J. Chem. Phys., 105, 8022 (1996).

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TA10 10 min 11:11 SPECTROSCOPIC DETECTION AND CHARACTERIZATION OF THE SELENOKETENYL (HCCSe) RADICAL DAVID A. HOSTUTLER, AND DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055. In 1979, Kirshnamachari and Venkitachalama reported a new transient absorption spectrum observed in the flash photolysis of selenophene. They found a series of strong, sharp bands in the 418 - 397 nm region and tentatively ascribed them to a C4 H4 species. We have detected the same band system by laser-induced fluorescence of the products of selenophene in a pulsed discharge jet experiment. Deuterium substitution experiments and the observed selenium isotope splittings show that the carrier of the spectrum contains a hydrogen and a selenium atom. We assign this band system to the previously unknown selenoketenyl or HCCSe radical. The B values for the ground and excited states have been determined by rotational analysis of high resolution spectra of the 000 bands of HCCSe and DCCSe. A combination of LIF and wavelength resolved fluorescence studies are in progress in an attempt to understand the vibronic structure in the spectrum. a S.

L. N. G. Krishnamachari and T. V. Venkitachalam, Chem. Phys. Lett. 67, 69 (1979).

TA11 15 min 11:23 JET AND LASER OPTOGALVANIC STUDIES OF THE ELECTRONIC SPECTRA OF GeH2 AND GeD2 AND AN IMPROVED STRUCTURE FOR GERMYLENE TONY C. SMITH, DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; WEI SHA and ALLAN G. ADAM, Department of Chemistry, University of New Brunswick, Fredericton, NB, Canada E3B 6E2. In 1995, we reported the structure of GeH2 , based on the assignment of 16 rotational lines in the LIF spectrum of the 000 ˜ 1 B1 - X ˜ 1 A1 electronic transition.a The number of observed rotational transitions was severely limited by band of the A an inhomogeneous predissociation in the excited state. We have now recorded high resolution LIF spectra of the 000 band of jet-cooled GeD2 using the pulsed discharge technique with a GeD3 Cl precursor. The spectrum is much more extensive than that of GeH2 due to less efficient tunneling through the barrier to dissociation on deuteration. Portions of the room temperature 000 band absorption spectrum of GeH2 have also been studied at Doppler-limited resolution using the laser optogalvanic technique. Rotational analysis of these spectra has provided the ground and excited state rotational constants for several germanium isotopomers. These data have been used to obtain an improved structure for germylene. a J.

Karolczak, W. W. Harper, R. S. Grev, and D. J. Clouthier, J. Chem. Phys. 103, 2839 (1995).

TA12 15 min 11:40 INVESTIGATION OF OPTOGALVANIC WAVEFORMS OF NEON AND ARGON UV TRANSITIONS FOR IDENTIFICATION OF THE PRIMARY ELECTRON COLLISIONAL IONIZATION PROCESS IN A HOLLOW CATHODE DISCHARGE H. E. MAJOR, and C. HARIDASS, Laser Spectroscopy Laboratory, Department of Physics and Astronomy and Center for the Study of Terrestrial and Extraterrestrial Atmospheres, Howard University, Washington, DC 20059; P. MISRAa , NASA Goddard Space Flight Center, Laser & Electro-Optics Branch, Code 554, Greenbelt, MD 20771. Laser-induced optogalvanic (OG) waveforms of neon ( 301.735 nm ) and arg on ( 320.366 nm) transitions in the UV region excited in commercial hollow cathode lamps at different currents were analyzed in order to identify and quantitatively characterize the dominant physical process contributing to the production of the optogalvanic signal. A rate equation model involving two or more states involved in the optical transitions was used to fit the observed waveforms. Effective decay rates of the states involved in the neon 1s4 - 4p8 (in Paschen notation) and argon 1s3 - 6p5 transitions, along with the associated amplitudes and instrumental time constants were determined using a non-linear least-squares fit of the observed data. Based on the present calculations, we conclude that the electron collisional ionization process is the main determining factor for the OG signal at 301.735 nm for neon and that of argon at 320.366 nm. a 1999-2000

NASA Administrator’s Faculty Fellow at Goddard Space Flight Center

108

TB. CONDENSED PHASE TUESDAY, JUNE 13, 2000 – 8:30 AM Room: 1009 SMITH LAB Chair: MARILYN JACOX, NIST, Gaithersburg, MD

TB01

15 min 8:30 4 MOLECULAR ROTATION IN SUPERFLUID He NANODROPLETS: THE VALIDITY OF A HYDRODYNAMIC MODEL CARLO CALLEGARI, ANDRE´ CONJUSTEAU, IRENE REINHARD, KEVIN K. LEHMANN, and GIACINTO SCOLES, Department of Chemistry, Princeton University, Princeton NJ 08544; FRANCO DALFOVO, Dipartimento di Matematica e Fisica, Universit`a Cattolica del Sacro Cuore, I-25121 Brescia (Italy). In order to accurately predict the effective moments of inertia (Ie ) of linear molecules rotating in superfluid 4 He droplets, we have recently devised a superfluid hydrodynamic model. In the present implementation, the helium density profile induced by the He-molecule interaction potential is first calculated at the Density Functional level, and then used as the input of the hydrodynamic equation for the irrotational motion of a viscousless fluid. The kinetic energy of the fluid (Ek ) is then used to calculate Ie via: Ek = 21
I ! 2 , where ! is the angular velocity of the molecule, and
I is the difference between Ie and the moment of inertia of the bare molecule.a The model relies on the assumption that the density of the fluid in the rotating frame of reference is independent of ! and can therefore be calculated in the limit of a static molecule (adiabatic following approximation). The validity of this approximation, and its first-order corrections will be discussed. The advantages and limitations of Density Functional Theory for calculating the true helium density will also be addressed, in a comparison with Quantum Monte Carlo results which recently became available for HCN and its oligomers.b a C. b E.

Callegari, A. Conjusteau, I. Reinhard, K.K. Lehmann, G. Scoles, and F. Dalfovo, Phys. Rev. Lett. 83, 5058 (1999); ibid. 84, 1848(E) (2000). Draeger and D. M. Ceperley, private communication.

109

TB02

15 min 8:47 4 MICROWAVE SPECTROSCOPY OF ISOTOPICALLY SUBSTITUTED MOLECULES IN He NANODROPLETS: A TEST OF THE ADIABATIC FOLLOWING APPROXIMATION ANDRE´ CONJUSTEAU, CARLO CALLEGARI, IRENE REINHARD, KEVIN K. LEHMANN, and GIACINTO SCOLES, Department Of Chemistry, Princeton University, Princeton NJ 08544. The microwave spectrum of HCN and DCN have been measured using Helium Nanodroplet Isolation Spectroscopy. A beam of cold (0.4 K) 4 He droplets is formed by expanding helium in vacuum through a 10 m nozzle. After collimation, the droplet beam is doped with the molecule of interest via standard pickup technique. During the time of flight of the seeded droplet in a 10 cm long waveguide, about 103 absorption/relaxation cycles occur with resonant radiation, which leads to evaporation of helium atoms from the droplet. This is detected as a depletion of the beam flux which is monitored optothermally. The J = 0 ! 1 transition for both molecules has been recorded at 72.140:01 GHz for HCN and 59.820:01 GHz for DCN. According to a recently developed superfluid hydrodynamic modela in which it is assumed that the helium density adiabatically follows the molecular rotation, the increase in moment of inertia caused by the helium is expected to be almost identical in each pair of isotopomers. In the case of HCN/DCN, it is predicted that DCN will be affected slightly less ( 1%) because the center of mass and the geometric center of DCN are closer together, which makes the rotor dynamically more spherical. Experimentally, the increase is found however, to be significantly smaller for the faster rotor, HCN, by about 11%. This result, which is in contradiction with the prediction of the hydrodynamic model, is interpreted as a breakdown of the adiabatic following approximation which is only valid for the slower rotors. Experiments with CH3 F and CD3 F are in progress and will be reported at the meeting. a C.

Callegari, A. Conjusteau, I. Reinhard, K.K. Lehmann, G. Scoles, and F. Dalfovo Phys. Rev. Lett. 83, 5058 (1999); 84, 1848(E) (2000)

TB03 15 min SPECTROSCOPY OF RUBIDIUM ATOMS AND MOLECULES ON COLD HELIUM NANODROPLETS

9:04

WOLFGANG E. ERNST, FRANK RUEDIGER BRUEHL AND RADU ALEX MIRON, Departments of Physics and Chemistry, Penn State University, 104 Davey Laboratory, University Park, PA 16802. Rubidium atoms were deposited on helium nanodroplets containing 5000 to 10000 atoms and having 0.4 Kelvin internal temperature. Alkali atoms remain on the surface of the droplets and can react to form dimers and larger aggregates. Laser excitation spectra as well as the dispersed fluorescence after excitation were measured for Rb atoms on helium in the wavelength range of the Rb D lines, i.e. from 12,000 to 13,000 wavenumbers. The spectra are qualitatively similar to those of Na and K on He. The observed emission indicates the same alkali-helium exciplex formation as in the case of Na-He a . Absorption and emission spectra of triplet dimers of rubidium were found near 15,000 and 16,800 wavenumbers. They were attributed to absorption from the triplet sigma ground state to excited triplet sigma and triplet pi states, respectively. First conclusions about the excited state potentials and comparisons with previous ab-initio calculations will be reported. a J.

Reho, C. Callegari, J. Higgins, W.E. Ernst, K. K. Lehmann, and G. Scoles, Faraday Discussions 108, 161-174 (1997).

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TB04 SPECTROSCOPY OF Mg ATOM-DOPED HELIUM NANODROPLETS

15 min

9:21

J. REHO, U. MERKER, MATTHEW R. RADCLIFF, K. K. LEHMANN, and G. SCOLES, Dept. of Chemistry, Princeton University, Princeton, NJ 08544. The technique of Helium Nanodroplet Isolation spectroscopy provides an ultra-cold environment (0.4 K) which can be doped with a variety of chromophores. Due to the unique nature of the droplets, the dopant will reside in one of two distinct trapping sites. Dopants may be solvated inside the droplet, in an environment similar to bulk liquid helium matrices. Or they may float on the surface, where the interaction with the helium is weak enough to give only minimal perturbations. Ancilotto et al.a have developed a model of solvation, based on the dopant-He pair potential, that uses a dimensionless parameter to determine the location of the dopant. Several systems have been studied so far (alkali, alkaline earths, and some transition and post-transition metals), but the boundaries between solvation and expulsion are not yet clear. 3 1S0 transition of Mg atom-doped helium nanodroplets. An interior Using LIF spectroscopy, we measured the 3 1P10 location of the Mg can be concluded from the blue shift and line broadening of the transition, which matches spectra of Mg atoms solvated in bulk liquid helium. The transition shows a splitting attributable to quadrupole-like deformations of the helium cavity surrounding the atom. Time-resolved studies show an increase in the lifetime of almost 20%, which can be quantitatively explained by the anisotropic distribution of the helium density surrounding the excited dopant, giving further evidence of solvation. Similar work on Ca atoms by Stienkemeier and co-workersb has shown that Ca atoms are surface species. Therefore the border between surface and solvated sites can be explored by studying the interaction of helium droplets with Mg and Ca atoms. a F. b F.

Ancilotto, P.B. Lerner, and M.W. Cole. J. Low Temp. Phys. 101, 1123 (1995) Stienkemeier, F. Meier, and H.O. Lutz. J. Chem. Phys. 107, 10816 (1997)

TB05 SPECTROSCOPY OF Al ATOMS SOLVATED IN HELIUM NANODROPLETS

10 min

9:38

J. REHO, U. MERKER, MATTHEW R. RADCLIFF, K. K. LEHMANN, and G. SCOLES, Dept. of Chemistry, Princeton University, Princeton, NJ 08544. We have performed the first measurement of the 3 2D 3 2P transition of Al atoms in liquid helium, using the helium nanodroplet isolation technique. The LIF excitation spectrum is broadened and blue shifted by amounts comparable to other Al transitions studied in bulk liquid helium, indicating solvation by the nanodroplet. As in the case of solvated Mg atoms, the Al transition shows a splitting attributable to quadrupole-like deformations of the cavity formed in the helium droplet. Time-resolved studies of wavelength-selected emission indicate a fast non-radiative quenching from the 3 2D state to the 4 2S state, which involves a transfer of 7000 cm 1 in less than 50 picoseconds. We have modeled this system using Hartree-Fock Damped Dispersion generated potential energy surfaces and shown that a ring of helium atoms forms around the node of the Al pz orbital. We conclude that as the number of He atoms in the waist of the orbital increases, the mixing of  character into the Al-He 1 2 state (as predicted by spin-orbit mixing) decreases. The lack of  character corresponds to less Al valence electron density in the xy plane, causing an attractive region into which the He atoms can be drawn. This can also be described as a localization of the valence electron in its pz orbital, occuring to a greater extent as the number of helium atoms increases.

111

TB06 X-RAY SPECTROSCOPY OF THE LIQUID WATER SURFACE

15 min

9:50

K. R. WILSON, B. S. RUDE, T. CATALANO, R. D. SCHALLER, J. G. TOBIN, and R. J. SAYKALLY, Department of Chemistry, University of California Berkeley, Berkeley, CA 94720. The molecular structure of liquid surfaces is a topic of much current interest relevant to problems in many disciplines. We present results from novel studies of liquid water microjets by a variety of spectroscopic methods. Soft X-ray absorption spectroscopy near the oxygen K-edge (530 eV) reveals a fine-structure pattern similar to that found for gaseous water monomers when the surface-selective total ion yield (TIY) is measured, but shows a broadened and blue-shifted spectrum when detecting the bulk-sensitive total electron yield (TEY). An analysis of the TIY EXAFS spectra provide evidence for a lengthening of the nearest neighbor O-O distance at the liquid water jet interface. Fourier Transform infrared microscopy measurements reveal a prominent free O-H stretching resonance and a strongly red-shift ”liquid band” when observing tangent to the microjet axis, but show a typical bulk water band at normal incidence. These results evidence a liquid water surface largely terminated by free OH bonds, and dominated by water molecules interacting at longer distances and with lower coordination number than in the bulk, thus supporting conclusions reached from computer simulations.

Intermission

TB07 15 min 10:30 HIGH RESOLUTION INFRARED ABSORPTION SPECTROSCOPY OF THE FIRST OVERTONE PURE VIBRATIONAL TRANSITION Q2 (0) OF SOLID PARAHYDROGEN HIROYUKI KATSUKI and TAKAMASA MOMOSE, Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, JAPAN. It has been shown that high-resolution infrared spectroscopy is applicable to the zero-phonon transitions of rotons and vibrons in solid hydrogen. Because the pure vibrational transitions Qn (0) [v=n 0, J=0 0] of solid parahydrogen become infrared-active only upon interaction with residual J=1 orthohydrogen, studies of the pure vibrational transitions under high-resolution provide detailed and accurate information on intermolecular interactions between hydrogen molecules. Here, we report the high-resolution absorption spectrum of the first overtone pure vibrational transition Q2 (0) of solid parahydrogen. The high-resolution spectrum of the Q2 (0) transition at around 8070 cm 1 was observed using a difference frequency laser systema . The spectrum shows a complicated spectral feature compared with that of the Q3 (0) transitionb . The v=3 vibrational exciton was found to be well localized on the parahydrogen molecule next to an orthohydrogen. On the other hand, since the vibron hopping matrix element of the v=2 state is comparable to the energy shift due to the existence of orthohydrogen, the observed rich spectral structure can be interpreted as due to the v=2 vibron hopping over a limited number of lattice sites in the crystal. We will discuss the quantitative analysis of the observed spectrum. a T. b R.

Momose, T. Wakabayashi, and T. Shida, J. Opt. Soc. Am. B 13, 1706 (1996). M. Dickson, T. Momose, T. J. Byers, and T. Oka, Phys. Rev. B 57, 941 (1998).

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TB08 15 min 10:47 STUDY OF STRUCTURAL FLUCTUATIONS IN AQUEOUS SOLUTIONS OF ACETIC ACID BY LIGHT SCATTERING METHODS B.S. OSMANOV, Department of Physics, The Ohio State University, Columbus OH 43210; F.H. TUKHVATULLIN, A. JUMABOEV, U. N. TASHKENBAEV, Samarkand State University, 703004 Samarkand, Uzbekistan. Two maxima of isotropic Rayleigh light scattering intensity for acetic acid-water solutions at 20 0C are observed at 0,06 and 0,12 mole fraction contents of acid. These maxima with temperature increasing is decreased. C=O vibrations band in Raman spectrum at contents of acid below 0,06 mole fraction has simple shape, whereas at above contents this band is complicated and consists of several lines. These date indicate about the changes of aggregated formations in mixture with concentration.

TB09 10 min 11:04 DIFFERENT POLARIZED COMPONENTS SHAPE OF RAMAN 1343 CM-1 BAND FOR NITRO-BENZENE AND ITS SOLUTIONS F. H. TUKHVATULLIN, A. JUMABOEV, U.N. TASHKENBAEV, S.A. OSMANOV, Z. MAMATOV, H. A. HUSHVAKTOV, Samarkand State University, 703004 Samarkand, Uzbekistan. In Raman spectra for 1343 cm-1 band of liquid nitro-benzene the maxima position of perpendicular and parallel polarized components are differed on =1,8 cm-1. At dilution of nitro-benzene in hexane (within the limits of solubility), chloroform and nitro-methane the frequency difference is decreased and is reduced to zero at the strong dilution. Peculiar kind of dependence the as a function of concentration for mixtures nitro-benzene with nitro-methane is associated with large dipole moment of solvent molecules.

TB10 15 min 11:16 INFRARED SPECTRA OF ACETONITRILE AND RELATED COMPOUNDS ADSORBED ON ALKALI HALIDE FILMS DENISE MAHALIDGE, N. SATISH CHANDRA, CANDICE TAYLOR, AND C. A. BAUMANN, Department of Chemistry, University of Scranton, Scranton, PA 18510-4626. The infrared spectra of acetonitrile (CH3 CN), deuterated acetonitrile (CD3 CN), fluoromethane and deuterated fluoromethane (CH3 F and CD3 F), and chloromethane (CH3 Cl) adsorbed onto sublimated films of alkali halides were observed. In acetonitrile, the symmetric CH stretch and the CN stretch are red-shifted relative to the gas phase frequencies, while the asymmetric CH stretch is blue shifted. Surface-induced splittings have been observed in the methyl bending and rocking modes. The spectra observed for fluoromethane are in agreement with those reported by Heidberg and coworkers a . Temperature-dependent broadening of the asymmetric CH stretch was observed in each of the compounds. This is attributed to dephasing of this vibration by an external mode of vibration, and is noticeably diminished upon deuteration. The effect of substituent (CN, F and Cl) and surface (NaCl, NaBr, KCl and KBr) on the dephasing dynamics of the methyl rotor on these films has been characterized. Acetonitrile exhibits an anomalously high activation energy to desorption, with a value (> 80 kJ mol 1 ) that approaches those seen for chemisorbed systems. The vibrational shifts and splittings will be used, along with desorption kinetics, to determine the mode of adsorption for this molecule. a J.

Heidberg, I. Hussla, Z. Szilagyi Z. Phys. Chem. 121, 145 (1980).

113

TB11 15 min 11:33 THE PHOTOLUMINESCENCE FROM HYDROGEN-RELATED SPECIES IN COMPOSITES OF SiO2 NANOPARTICLES YURI D. GLINKA, SHENG-HSIEN LIN AND YIT-TSONG CHEN, Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, and Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan. Dispersed photoluminescence (PL) spectra of silica (SiO2 ) nanoparticles induced by ArF (193 nm) and Nd:YAG (266 nm) lasers have been observed.a PL measurements from the composites of silica nanoparticles (the primary particle size 7 and 15 nm) as a function of heat-treatment temperature show that the PL results from hydrogen-related species and thermally produced structural defects. The green PL exhibits a progression with spacings of
 630 cm 1 assigned to the bending vibration of Si-H on the surface of particles. The spacings increase up to
 1200 cm 1 when Si-H and non-bridging oxygen (Si-O) form interfacial water species. The two-photon (TP) induced PL with an ArF laser excitation has also been studied. The TP-produced excitons can result in a self-trapped exciton recombination (blue band), surface hydrogen-related centers (green band) and bulk non-bridging oxygen hole centers (red band). Relaxation of free TP-produced excitons and energy transfer of the excitons to the surface and bulk defects will be discussed. a Y.

D. Glinka, S. H. Lin and Y. -T. Chen, Appl. Phys. Lett., 75, 778 (1999).

TB12 10 min 11:50 ISOMERIC STRUCTURAL STUDY OF DIAMINES IN LIQUID STATE AND ITS INTERACTIONS WITH ALCOHOLS THROUGH DIELECTRIC SPECTROSCOPIC METHOD N.M.MORE,, Department of Physics, Dr B.A..M University, Aurangabad, PIN-431004, Mharashtra (India); S.C.MEHROTRA, Department of Electronics and Computer Science, Dr.B.A.M. Univesity, Aurangabad, PIN431004, Maharashtra (India). Dielectric relaxation parameters of diamines HI2 N - (CHI2 )In - NHI2 (n=0-6) in alcohols in microwave frequency range 10 MHz to 20 GHz has been determined using time domain reflectometry a . The HP54750A digitizing oscilloscope with HP54754A TDR module is used for these measurements. The time dependent data is processed to obtain complex reflection coefficient. The complex permittivity spectra is obtained by applying bilinear calibration method. The Excess dielectric parameters and thermodynamic parameters are obtained using dielectric constant and relaxation time. These systems show interesting change in dielectric parameters with change in concentration and temperature. The paper discusses the conformation obtained regarding isomeric forms of diamines through their excess parameters. a A.C.

Kumbharkhane, S.M. Puranik and S.C.Mehrotra,Faraday Transactions, 1569-1573, JCFTEV(10)-1499-1665 (1991).

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TC. NEGATIVE IONS TUESDAY, JUNE 13, 2000 – 8:30 AM Room: 1000 McPHERSON LAB Chair: W. CARL LINEBERGER, University of Colorado, Boulder, CO

TC01 Invited Talk 30 min 8:30 UNUSUAL NEGATIVE MOLECULAR IONS AND DIANIONS AND CHEMICAL BONDS INVOLVING RYDBERG ORBITALS JACK SIMONS, Department of Chemistry and Henry Eyring Center for Theoretical Chemistry, University of Utah, Salt Lake City, Utah 84112.

115

TC02 15 min 9:05 CARBON CHAIN ANIONS OF ASTROPHYSICAL INTEREST: PHOTODETACHMENT SPECTROSCOPY AND THEORETICAL CALCULATIONS ¨ NICHOLAS M. LAKIN, M. TULEJ, M. PACHKOV, F. GUTHE AND J.P. MAIER, Institut f¨ur Physikalische Chemie, Universit¨at Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.. The recent observation of close coincidences between several of the diffuse interstellar bands and vibronic features of the X 2 g system of C7 in the gas phase has lead to discussion about the possible role of carbon-based anions in the interstellar mediuma . In this contribution spectra of the anions C3 , C5 and C7 , obtained using photodetachment spectroscopy, are presented and interpreted using the results of ab initio calculations. Transitions to both bound electronic states and to states lying above the photodetachment threshold are observed; the latter are assigned as Feshbach resonances on the basis of their calculated electronic structuresb . Lifetimes for these resonant states are estimated from the observed rotational structure. The spin-orbit splittings in these anions are calculated theoretically. The results confirm the assigments of the Renner3 components of the Teller structure in C3 . For C7 the calculations have lead to the identification of the = 32 2 0 1 2 2 A u X g 00 and 10 bands in the experimental spectrum. The implications for future laboratory and astronomical searches for transitions in these anions are discussed.

A2 u

a M. b M.

Tulej, D. A. Kirkwood, M. Pachkov and J. P. Maier Astrophys. J. 506, L69 (1998). Tulej, J. Fulara, A. Sobolewski, M. Jungen and J. P. Maier J. Chem. Phys. 112(8), 3747 (2000).

TC03

15 min

9:22

GROUND STATE POTENTIAL ENERGY SURFACE AND ROVIBRATIONAL STRUCTURE OF C3 H NICHOLAS M. LAKIN, Institut f¨ur Physikalische Chemie, Universita¨ t Basel, Klingelbergstrasse 80, CH4056 Basel, Switzerland; M. HOCHLAF AND P. ROSMUS, Theoretical Chemistry Group, Universit´e de Marne-La-Vale´e, F-77454 Champs sur Marne, France. The detection of molecular anions in the laboratory by spectroscopic methods and the interpretation of these spectra is greatly aided by accurate theoretical calculations for the geometries and relative stabilities of the different isomers. This contribution describes a six dimensional ab initio potential energy surface (PES) for the singlet ground state of C3 H calculated at the CCSD(T)/aug-cc-pVQZ level. In agreement with previous studiesa , the global potential minimum corresponds to a planar cyclic isomer. A local minimum is also located about 2500 cm 1 higher in energy, corresponding to a planar trans bent isomer. The PES, represented by a fitted analytical form in the region of the two minima,is used in variational calculations to determine anharmonic rovibrational term values (J 2) for both isomers and their deuterated analogues. Rotational, centrifugal distortion and vibration-rotation constants are evaluated. The implications of the theoretical calculations for future investigations of C3 H and C3 D using microwave, infrared and photodetachment spectroscopies are discussed. a K.

Aoki, K. Hashimoto, S. Ikuta and O. Nomura Chem. Phys. Lett. 242, 527 (1995).

TC04 15 min AN EFFICIENT MECHANISM LEADING TO THE FORMATION OF NEGATIVE IONS IN SPACE

9:39

RADOSLAVA V. TERZIEVA and ERIC HERBST, Departments of Physics and Astronomy, and Chemical Physics Program, The Ohio State University, Columbus, OH 43210. Recent spectroscopic studies of carbon chain anions in the gas phase, and more specifically of C 7 , have brought insight into the long-standing mystery of the unexplained diffuse interstellar bands (DIBs). Previously, negative ions had not been considered highly abundant in interstellar clouds, and the question of efficient mechanisms leading to their formation had not been investigated in great detail. We present a statistical calculation of the rate coefficients for radiative attachment of an electron to small linear carbon clusters containing 4 to 9 atoms. Our conclusion is that for molecules with 6 or more C atoms, the attachment occurs on every collision at the low temperatures of diffuse interstellar clouds.

116

TC05

15 min

9:56

TIME RESOLVED DYNAMICS OF ELECTRONIC EXCITATIONS IN C3 ¨ H.J. MUNZER, ¨ ¨ S. MINEMOTO, J. MULLER, R. FROMHERZ, G. GANTEFOR, J. BONEBERG, and P. LEIDERER, Universit¨at Konstanz, 78457 Konstanz, Germany.

a S.

0,07

Peak A / Peak B [a.u.]

Experiments have been performed on the ultrafast electron dynamics of mass selected cluster anions. The setup consists of a pulsed arc cluster ion source (PACIS), a time-of-flight mass spectrometer, a magnetic-bottle-type time of flight electron spectrometer, and a femtosecond laser. Time resolved pump/probe photoelectron spectra are recorded. We present first data on C3 a . Photoelectron spectra were obtained for a set of increasing delays between pump pulse (excitation of the anion) and probe pulse (detachment of the ad-electron). Interpretation of the series of spectra yields an assignment of the involved electron states and, moreover, the lifetime of the excited state. The method is suitable to study all kinds of electronic excitation and relaxation processes in mass selected nanoparticles.

t = 2.6 ± 0.7 ps

0,06

0,05

0,04

0,03 -5

0

5

10

15

20

25

30

35

Delay [ps]

Fig. 1: The decay of the first excited state of C3 as extracted from the time-resolved pump/probe photoelectron spectra. An exponential fit is shown corresponding to a lifetime of 2:6  0:7 ps

Minemoto, J. M¨uller, G. Gantef¨or, H.J. M¨unzer, J. Boneberg, and P. Leiderer, Phys. Rev. Lett. accepted for publication

TC06

10 min

10:13

COUPLED CLUSTER CALCULATIONS FOR C4 H , AN ANION OF INTEREST TO ASTROCHEMISTRY P. BOTSCHWINA, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany.

Intermission TC07

10 min

OBSERVATION OF METASTABLE AUTODETACHING STATES OF METHIDE, CH3

10:40

a

STEPHEN E. MITCHELL and JOHN W. FARLEY, Department of Physics, University of Nevada, Las Vegas, NV 89154. Metastable autodetaching states of methide, CH3 , have been observed, with an autodetachment lifetime of tens to hundreds of s. The excited state responsible for autodetachment is unknown, but could be a vibrationally excited state, because one vibrational quantum of the  1 ,  3 , or  4 vibrational mode has enough internal energy to produce autodetachment of the low-electron -affinity (0.08 eV) ion. The long lifetime may arise from small Frank-Condon overlap between the initial pyramidal ion and the final planar neutral. There are presently no theoretical calculations of the autodetachment mechanism or lifetimes. a Supported

by DOE/EPSCoR

117

TC08 THRESHOLD ION-PAIR PRODUCTION SPECTROSCOPY (TIPPS) of H2 S

15 min

10:52

Q. J. HU, X. K. HU, R. C. SHIELL, and J. W. HEPBURN, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Threshold Ion-Pair Production Spectroscopy (TIPPS) of H2 S will be presented. Hydrogen sulfide molecules were excited into weakly bound H — HS+ Rydberg-like state using XUV photons and then dissociated with pulsed electric fields. The TIPP spectrum was recorded by detecting the negative ion H . The spectrum agrees quite well with a simulated spectrum. From the TIPP spectrum the H-SH bond dissociation energy could be determined within several wavenumbers. We found that the positive ion product, HS+ , could be highly rotationally, or even vibrationally excited. The dynamics of the photodissociation process of H2 S ! H + HS+ will be discussed and compared to the process of H2 S ! H+ + HS .

TC09 15 min VIBRATIONAL SPECTROSCOPY OF NEGATIVE IONS BY STIMULATED RAMAN PUMPING

11:09

MICHAEL R. FURLANETTO, NICHOLAS L. PIVONKA, and DANIEL M. NEUMARK, Department of Chemistry, University of California, Berkeley, CA 94720. We have been developing methods for studying the vibrational spectroscopy of Raman-active modes of gas-phase negative ions. Several years ago, we demonstrated that C2 could be vibrationally excited by stimulated Raman pumping (SRP); in that study, we monitored the excitation by resonant two-photon detachment of the aniona . Since then, we have been investigating other, more general methods by which we could monitor the success of SRP. Recently we have demonstrated that anion photoelectron spectroscopy can be used in conjunction with SRP for vibrational spectroscopy of C2 b . Currently, we are attempting to couple SRP with the vibrational predissociation of a weakly-bound reporter species; in particular, we are focusing on the ArBrHI and ArNCO systems. Together, these methods constitute a quite general method for studying the vibrational spectroscopy of gas-phase negative ions. Ultimately, we hope to use the vibrationally excited ions produced by SRP to extend our studies of the transition states of neutral bimolecular reactions by the photodetachment of anion precursorsc ; for instance, by exciting the hydrogen-atom stretch in BrHI , we should be able to reach the transition state of the HI + Br ! HBr + I reaction by photodetachment. a E.

de Beer, Y. Zhao, I. Yourshaw, and D. M. Neumark, Chem. Phys. Lett. 244, 400 (1995) . R. Furlanetto, N. L. Pivonka, T. Lenzer, and D. M. Neumark, Chem. Phys. Lett., in preparation. c S. E. Bradforth, A. Weaver, D. W. Arnold, R. B. Metz, and D. M. Neumark, J. Chem. Phys. 92, 7205 (1990) .

b M.

118

TC10 10 min 11:26 TWO-ELECTRON WAVEFUNCTIONS FOR THE GROUND AND EXCITED STATES OF ALKALI NEGATIVE IONS S. MAGNIER, Laboratoire de Physique Mol´eculaire et des Collisions, Technopoˆ le 2000, 1 Bd Arago, F-57078 Metz Cedex 3.

TC11 15 min 11:38 RESONANCES IN SN 2 REACTIONS: TWO-DIMENSIONAL QUANTUM CALCULATIONS ON A NEW POTENTIAL ENERGY SURFACE FOR CL + CH3 CL J. HAUSCHILDT, R. SCHINKE, Max-Planck-Institut f¨ur Str¨omungsforschung, Bunsenstr. 10, D-37073 G¨ottingen, Germany; P. BOTSCHWINA and S. SCHMATZ, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstr. 6, D-37077 G¨ottingen, Germany.

119

TD. JET AND BEAM TUESDAY, JUNE 13, 2000 – 8:30 AM Room: 1015 McPHERSON Chair: JOHN MUENTER, University of Rochester, Rochester, NY

TD01 ROTATIONAL SPECTRUM OF DIMETHYL METHYLPHOSPHONATE

15 min

8:30

R. D. SUENRAM, F. J. LOVAS, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD., 208998441; A. LESARRI, Departamento de Qu´ımica F´ısica, Facultad de Ciencias, Universidad de Valladolid, 47005 Valladolid, Spain; J. O. JENSEN, and A. C. SAMUELS, Passive Standoff Detection Group, Edgewood Chemical and Biological Center, Edgewood Area, Aberdeen, MD 210105424. Dimethyl methylphosphonate [(CH3 O)2 P(=O)CH3 ] is a relatively nontoxic chemical that is often used as a chemical weapons (CW) simulant to test the sensitivity of analytical techniques. We have undertaken a microwave investigation of its rotational spectrum in order that Fourier transform microwave (FTMW) spectroscopy can be used in conjunction with other analytical methods in test and analysis procedures. Analysis of the spectrum is complicated by several factors. First, there are a number of possible low energy conformational isomers. Second, the methoxy methyl groups have low barriers to internal rotation which causes large splittings in the transitions. And finally, in the observed spectrum, the two methoxy groups in the molecule are not equivalent and they undergo a concerted tunneling motion which adds additional splittings to the spectrum. Fortunately the third methyl top, which is attached directly to the phosphorous atom, has a high barrier to internal rotation and adds only small splittings to the transitions. The basic rotational spectrum is that of a rather asymmetric prolate top ( = 0.41) with the dominant dipole selection rule along the cprincipal axis. Spectral splittings which arise from the internal rotation of the methyl tops and the concerted tunneling motion can, to a first approximation, be described using the Hamiltonian developed for the methanol dimer. (See the following paper.) In the present paper, only a rigid rotor analysis will be given and the structure of the observed conformational isomer will be presented. A comparison of the ab initio calculated structures and barriers to internal rotation will be made with the experimental results.

TD02 GROUP THEORY OF DIMETHYL METHYL PHOSPHONATE

15 min

8:47

JON T. HOUGEN, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441; NOBUKIMI OHASHI, Department of Physics, Faculty of Science, Kanazawa University Kakuma, Kanazawa 920-1192, Japan. The dimethyl methyl phosphonate molecule (CH3 O-)2 P(=O)-CH3 has five large-amplitude motions, consisting of rather traditional three-fold-barrier internal rotations for each of the three methyl tops, together with less traditional skeletalflexing internal rotations about each of the two P-O bonds. Experimental evidence (previous talk) indicates that all three methyl tops are inequivalent, with the corresponding splittings in a (J + 1)0;J +1 - J0;J pattern of the order of 20 MHz, 2 MHz and 0.2 MHz, respectively. A group theoretical treatment which neglects the smallest torsional tunneling motion leads to a permutation-inversion molecular symmetry group G18 , which is a subgroup of the group G36 used in our earlier study of the methanol dimer. This G18 group is chiral, in the sense that two-fold and four-fold separable degeneracies occur, i.e., degeneracies occur which are not intrinsic to the character table of the group, but result instead from an application of time reversal. Results from this G18 group nicely explain the qualitative features of the a-type spectral patterns, and work is in progress to apply the results also to b-type and c-type patterns. When rotation of the third methyl top is considered, the appropriate group is G54 . Work on splitting patterns from this group is in progress.

120

TD03 VIBRATIONAL SPECTROSCOPY AND A POTENTIAL SURFACE FOR THIOPHOSGENE

15 min

9:04

BRENT STRICKLER and MARTIN GRUEBELE, Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801. Vibrationally excited SCCl2 is a model for nonhydrogenic vibrational energy redistribution (IVR). Spectroscopic characterization of the ground and excited singlet states has been made by fluorescence excitation and high resolution dispersed ˜ B˜ dispersed fluorescence spectra, the ground fluorescence measurements. Using over 500 transitions from several X 1 1 electronic state has been mapped up to 20,200 cm with an error  3 cm . The adjustable parameters of an analytical six-dimensional ab initio potential surface have been fitted to the fluorescence transitions using a nonlinear least squares algorithm. The fitted potential surface provides an experimental standard for IVR quantum dynamics calculations.

TD04 15 min 9:21 TOLUENE INTERNAL ROTATION: REFINED BARRIER HEIGHT IN S1 , SIGN OF V6 , AND MOTION ALONG THE TORSIONAL COORDINATE.a DAVID R. BORST and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. High resolution electronic spectra of three torsional bands in the S1 S0 electronic transition of toluene have been recorded in a molecular beam. The analyses of these spectra provide a unique and unambigious determination of the sign of the V6 hindering potential in both electronic states; V6 (S0 ) = -4.874 cm 1 and V6 (S1 ) = -26.375 cm 1 . Furthermore, the data show that both F and the frame rotational constant AF vary between torsional levels within the S1 manifold. Information about geometric changes responsible for these differences will be discussed, along with the validity of the one-dimensional, rigid frame-rigid top model. a Work

supported by NSF

TD05 15 min 9:38 DESIGN AND PREFORMANCE CHARACTERISTICS OF A CONTINUOUS SLIT EXPANSION-FTIR SPECTROMETER SYSTEM ROBERT L. SAMS, ROBIN S. MCDOWELL , THOMAS A. BLAKE and STEVEN W. SHARPE, Pacific Northwest National Laboratory, P. O. Box 999, Mail Stop K8-88, Richland, WA 99352 (PNNL is operated for the US Department of Energy by the Battelle Memorial Institute under contract DE-AC06-76RLO 1830). Supersonic molecular beam sources have been used by the spectroscopy community to simplify high resolution, infrared spectral analysis for almost four decades. Originally, a continuous round orifice was utilized in conjunction with tunable lead-salt, difference frequency, f-center and a variety of other laser sources. More recently, a number of research groups have replaced these laser sources with Fourier transform infrared spectrometers (FTIRS) in favor of their extensive spectral coverage. These beam-FTIR systems have been operated in a variety of modes including asynchronous pulsing of the beam source and multiple pin-hole, CW sources. We report the design specifications and operating performance of a Bruker-120HR FTIRS coupled to a 12 cm x 50 m continuous slit molecular beam source. The PNNL FTIR-jet spectrometer system incorporates a continuous expansion source pumped by a high throughput (600 Torr liter/second) system of roots blowers. Typical rotational cooling temperatures of 10 K are routinely achieved while vibrational temperatures appear to be significantly warmer (100 K). Spectral line widths associated with either He or Ar expansions are almost always smaller than the FTIRS ultimate resolution of 0:0015 cm 1 (45 MHz). Despite a significantly lower signal-to-noise ratio when compared to a laser based system, the FTIR-jet spectrometer offers significant advantages including extensive spectral coverage from 4000 to 400 cm 1 . To demonstrate the system’s performance, a number of test cases including fluorocarbons, nitrous oxide monomer, and the weakly bonded nitrous oxide-argon dimer will be presented.

121

TD06 A SLIT-JET INFRARED SPECTRUM OF 1,3-BUTADIENE

15 min

9:55

MARJO HALONEN, DAVID NESBITT, AND MICHAL FARNIK, JILA, University of Colorado, Campus Box 440, Boulder, Colorado 80309. A slit-jet infrared spectrum of the CH stretching fundamental band 1 of trans-1,3-butadiene has been measured with a difference frequency laser system in the wavenumber region 3090 - 3120 cm 1 . The optical resolution of the spectrum is about 100 MHz. An a=b-type hybrid band structure is observed. A detailed analysis of the spectrum will be presented, and the role of large amplitude motion and intramolecular vibrational energy redistribution will be discussed.

Intermission TD07 HIGH RESOLUTION INFRARED SPECTRA OF 2-METHYL-1-BUTEN-3-YNE

10 min

10:30

JOHN KESKE and B. H. PATE, Department of Chemistry, University of Virginia, McCormick Rd.,P.O. BOX 400319 Charlottesville, VA 22904. The high resolution infrared spectrum (5MHz) of the acetylenic C-H stretch of 2-methyl-1-buten-3-yne (HCCC(CH3 )=CH2 ) has been assigned using microwave-infrared double-resonance spectroscopy. The double-resonance capabilities of our electric-resonance optothermal spectrometer allow for unambiguous rotational assignment of the extremely dense rovibrational spectrum. The high-resolution infrared spectrum shows substantial fragmentation and is evidence of extensive intramolecular vibrational energy redistribution (IVR). The local perturbations split the transition moment into a set of transitions containing as many as 100 or more components. Due to the rapid increase in state density as J increases only J=0-3 Ka=0-2 transitions have been assigned. From the analysis of these spectra the survival probability of the acetylenic C-H stretch has been determined to be 95 ps. Initial spectra of the ethylenic (C=CH2 ) hydrogens indicate a substantially longer IVR lifetime than for the acetylenic hydrogen. Preliminary work on the rotational spectra of vibrationaly-excited 2-methyl-1-buten-3-yne will also be presented.

TD08 15 min 10:42 FEMTOSECOND PUMP/PROBE STUDY OF VIBRATIONAL LIFETIMES OF THE FUNDAMENTAL ACETYLENIC C-H STRETCH IN DILUTE SOLUTIONS HYUN S. YOO and BROOKS H. PATE, Department of Chemistry, University of Virginia, McCormick Rd., P.O. Box 400319, Charlottesville, VA 22904. Vibrational lifetimes of the acetylenic C-H stretch for eight molecules in dilute carbon tetrachloride (CCl4 ) solutions have been measured at room temperature using femtosecond infrared pump/probe spectroscopy. The vibrational population relaxation in solution is driven by two factors; intramolecular vibrational energy redistribution (IVR) and collision induced relaxation. The solvent-induced relaxation rate has been determined by measuring the vibrational lifetimes of propyne, propargyl chloride, and propargyl bromide in CCl4 solutions. High-resolution gas-phase infrared studies of these molecules using an electric-resonance optothermal molecular-beam spectrometer (EROS) show no evidence of IVR. The solventinduced relaxation rate is approximately 2x1010 s 1 in dilute CCl4 solutions. The femtosecond pump/probe study shows that lifetimes are independent of the vibrational state densities of molecules, where the state densities range from 100 to 105 states/cm 1 around 3330 cm 1 , with propyne (HCCCH3 ) being the smallest and trimethylsilylacetylene (HCCSi(CH3 )3 ) being the largest. The overall trend of the relaxation rates, however, strongly resembles the trend of molecules’ IVR rates studied with EROS, which demonstrates the solvent-induced energy relaxation is unvarying for different molecules in the same solvent.

122

TD09 15 min 10:59 MODE-SPECIFICITY AND NON-RRKM KINETICS IN THE CONFORMATIONAL ISOMERIZATION OF 4CHLOROBUT-1-YNE JOHN KESKE and B. H. PATE, Department of Chemistry, University of Virginia, McCormick Rd., P.O. BOX 400319 Charlottesville, VA 22904. We have measured the rate of conformational isomerization of 4-chlorobut-1-yne at an energy of 3330 cm 1 above the zeropoint level through the rotational spectroscopy of single molecular eigenstates. From the spectrum of the J=3-J=4 rotational transition of several eigenstates in this energy region we measure a unimolecular conformational isomerization rate of 1.2x1010 s 1 . This rate is more than two orders-of-magnitude slower than the rate calculated using RRKM theory: 1x1013 s 1 . Furthermore, from the eigenstate-resolved rovibrational spectrum of the acetylenic C-H stretch we find that there is strong mode-specificity in the isomerization rate. Coherent preparation of the acetylenic C-H stretch of 4-chlorobut-1-yne leads to even slower isomerization with an upper limit of the rate set by the measured rate of intramolecular vibrational energy redistribution: 3.3x108 s 1 .

TD10 15 min 11:16 ROTATIONAL ANALYSIS OF CYCLOHEXYL METHYLPHOSPHONOFLUORIDATE (CYCLOHEXYL SARIN (GF)) R. D. SUENRAM, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 208998441; J. O. JENSEN, A. C. SAMUELS, M. W. ELLZY, and J. M. LOCHNER, Passive Standoff Detection, Edgewood Area, Aberdeen Proving Ground, MD 210105424. In an effort to use Fourier transform microwave spectroscopy as a detection technique for chemical compounds related to chemical weapons (CW) technology, we have investigated the rotational spectra of the title compound. This work was carried out using a Fourier transform microwave (FTMW) spectrometer in a surety laboratory at the ECBC in Aberdeen, MD. A survey spectrum was recorded from 11 GHz to 18 GHz. A rather rich spectrum was observed which was assigned to two conformational isomers. Each isomer has all three selection rules active indicating Cs symmetry for both isomers. Details of the rotational spectra and analysis will be given and the conformational structures presented.

TD11 CONFORMATIONAL ANALYSIS OF MUSTARD GAS HYDROLYSIS PRODUCTS

15 min

11:33

R. D. SUENRAM, D. F. PLUSQUELLIC, B. MATE´ , and A. R. HIGHT WALKER, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 208998441; J. O. JENSEN and A. C. SAMUELS, Passive Standoff Detection, Edgewood Chemical and Biological Center, Edgewood Area, Aberdeen Proving Ground, MD 210105424. In an effort to use Fourier transform microwave spectroscopy as a detection technique for chemical compounds related to chemical weapons (CW) technology, we have investigated the rotational spectra of ethyl sulfide, thiodiglycol and the intermediate compound 2hydroxyethyl ethyl sulfide. In addition to their importance in CW analysis, they present interesting spectroscopic problems since we have identified three, three, and two conformational isomers, respectively for the above compounds in the gas phase. Details of the rotational analysis using a new interactive assignment program will be given. In addition, a comparison will be made between the observed and ab initiocalculated conformational structures.

123

TD12 OVERTONE SPECTROSCOPY AND DYNAMICS OF HCFC COMPOUNDS

10 min

11:50

X. CHEN, (Present address: Department of Chemistry, UC Berkeley, Berkeley 94720-1460, California, USA); A. MELCHIOR, Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; I. BAR, The Institutes for Applied Research, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel; and S. ROSENWAKS, Department of Physics, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel. Photoacoustic spectra of the second, third and fourth overtones of methyl C-H stretches of CH3 CF2 Cl and CH3 CFCl2 and of the N = 3, N = 7/2 and N = 4 C-H stretch-bend polyads of CHFCl2 were measured at room temperature. For the last two compounds also the action spectra were obtained via photodissociation of the jet-cooled vibrationally excited molecules combined with mass spectroscopic detection of the photofragments. In the action spectra fragments of H, Cl(2 P3=2 ) [Cl] and Cl(2 P1=2 ) [Cl ] were detected, due to enhanced C-Cl and C-H bond breaking indicating energy flow out of the initially prepared states. A simplified local mode model for C-H stretching, including the stretch-deformation Fermi resonances, was used to interpret the multi-peak structure of the spectra of CH3 CF2 Cl and CH3 CFCl2 . The action spectra are significantly narrower than the room temperature photoacoustic spectra due to reduction of the rotational inhomogeneous structure. In CHFCl2 the action spectra enabled to resolve the components arising from the different isotopomers of the precursor and the resonance splitting attributed to a local resonance of the 7/21 polyad component with a combination of the 7/23 component and the ClCCl bending. This splitting reflects an oscillation period of ˜ 3 ps for the vibrational redistribution and indicates that the coupling of the stretch-bend mixed state to the rest of the molecule is weaker than the stretch-bend coupling itself. The yield of Cl photofragments was found to be about half that of Cl for ˜ 235 nm photolysis of vibrationally excited CH3 CFCl2 and CHFCl2 . The initial vibrational state preparation increases the Cl /Cl branching ratio, as compared to the nearly isoenergetic one-photon 193 nm photolysis of vibrationless ground state CH3 CFCl2 , implying that it alters the photodissociation dynamics. Possible reasons for this enhancement are discussed.

124

TE. INFRARED TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1153 SMITH LAB Chair: ROBERT McKELLAR, National Research Council of Canada, Ottawa, Canada

TE01

15 min 10 THE INFRARED SPECTRUM OF THE B2 H6 BANDS IN THE BRIDGE B-H STRETCHING REGION

1:30

W. J. LAFFERTY, Optical Technology Division, NIST, Gaithersburg, MD 20899, USA; J.-M. FLAUD, Laboratoire de Photophysique Mol´eculaire, CNRS, Universit´e Paris-Sud, 91405, Orsay, Cedex, France; ¨ H. BURGER and G. PAWELKE, Anorganische Chemie, FB 9, Universita¨ t-GH, D-42097, Wuppertal, Germany. We have been studying the spectrum of the 13 region of 10 B2 H6 around 5 m using high resolution Fourier transformed spectra of a pure isotopic sample. The 13 band, arising from the bridge-hydrogen stretching vibration, is highly perturbed by numerous nearby lying combination levels. At this point we have performed an almost complete assignment of the 13 fundamental as well as the much stronger combination band, v + 15 , and the 9 + 15 band. The energy level fitting has proven to be very difficult. At the present stage six interacting states are included, including the three bright states 131 , 51 15 and 91 151 and three dark states 71 141 , 41 181 and 31 51 . The observed energy levels are calculated in a satisfactory way but not to within the experimental accuracy (about 0.0002 cm 1 ). We hope to present a complete analysis including interaction constants between the resonating states.

TE02 10 min 1:47 12 CD OH MOLECULE: A GOOD LASER SOURCE OF FAR-INFRARED RADIATION IN THE SPECTRAL RANGE 3 22 TO 3030 MICRONS E. C. C. VASCONCELLOS, Instituto de F´ısica ”Gleb Wataghin,” Departamento de Eletrˆonica Quˆantica, Universidade Estadual de Campinas (UNICAMP), 13083-970 Campinas, SP, Brazil; M. JACKSON, Department of Physics, University of Wisconson, LaCrosse, WI 54601; M. D. ALLEN and K. M. EVENSON, Time and Frequency Division, National Institute of Standards and Technology, Boulder, CO 80303-3328. 12 CD OH is one of the most important methanol isotopomers for the generation of far-infrared (FIR) radiation. Over 400 3 FIR laser lines in the wavelength range 22 to 3030 m have been discovered in this molecule, mainly by optically pumping it with a CO2 laser. High frequency laser lines with wavelength below 160 m account for forty-five percent of the lines. This work presents an overview of the FIR laser lines discovered in 12 CD3 OH along with their frequency measurements, and recently obtained data for newly discovered lines. This will serve to highlight the availability of frequency measured laser lines that can be used in various applications, with particular interest in the high-energy range (  160 m). Several of the frequency measured laser lines have already been used in laser magnetic resonance spectroscopy.

125

TE03 15 min INDUCED ABSORPTION SPECTRA OF THE FUNDAMENTAL BAND OF D2 IN D2 -CO AND D2 -N2

1:59

G. VARGHESE, C. STAMP, and S. PADDI REDDY, Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John’s, Newfoundland, A1B 3X7, Canada. The collision-induced infrared fundamental band of D2 in D2 -CO and D2 -N2 binary mixtures were recorded at 298 K with a sample pathlength of 105.2 cm at various densities of the binary mixtures up to 115 amagat for several base densities of D2 . Binary and ternary absorption coefficients were obtained from the measured integrated absorption coefficients. The spectra have been interpreted in terms of the overlap transitions Qov (J), J=0 to 5 and by the following quadrupolar double transitions of D2 +CO and D2 +N2 : O1 (J)(D2 )+Q0 (J)(CO/N2 ), Q1 (J)(D2 )+Q0 (J)(CO/N2 ), S1 (J)(D2 )+Q0 (J)(CO/N2 ), and Q1 (J)(D2 )+S0 (J)(CO/N2 ). Analysis of the absorption profiles was performed by assuming appropriate line-shape functions a and characteristic half-width parameters Æd and Æc of the overlap transitions and Æq of the quadrupolar transitions a See

S. P. Reddy, ”Phenomena Induced by Intermolecular Interactions” edited by G. Birnbaum, Plenum, New York, 1985.

TE04 15 min 2:16 HELIUM DROPLET SPECTROSCOPY AS A TOOL FOR EXPLORING MOLECULAR AGGREGATION: VAN DER WAALS COMPLEXES OF HF WITH MULTIPLE H2 MOLECULES, PURE ORTHO-, PURE PARA- AND MIXED COMPLEXES DAVID T. MOORE, ROGER E. MILLER, Department of Chemistry, University of North Carolina, Chapel Hill NC, 27599. Pendular spectra of HF-(o-H2 )n(p-H2 )m [n,m=0,6] van der Waals complexes in liquid helium droplets have been recorded. The compositions of the different complexes were determined by comparing pendular spectra taken with normal and para-enriched hydrogen. Field-free, rotationally resolved spectra were also obtained for the (n,m)=(0,2), (1,1) and (2,0) complexes. The results have been used to draw inferences about the relative aggregation behaviors of ortho- and para-H2 with HF.

TE05 15 min 2:33 THE SPECTROSCOPY OF THE H2 -HF AND D2 -HF BINARY COMPLEXES IN LIQUID HELIUM DROPLETS DAVID T. MOORE, ROGER E. MILLER, Deptartment of Chemistry, University of North Carolina, Chapel Hill NC, 27599. Rotationally resolved liquid helium droplet spectra of the HF-H2 and HF-D2 van der Waals complexes have been recorded. The different nuclear spin states of the H2 and D2 molecules produce distinguishable complexes, and while the orthoH2 a ; b and ortho- and para-D2 c ; d complexes have been observed in the gas phase, this is the first time the para-H2 complex with HF has been observed. Comparsions of the gas phase and helium droplet spectra will be presented, with particular emphasis on the reduction of the rotational constants of the complexes from their gas phase values. a K.

W. Jucks, R. E. Miller, J. Chem. Phys. 87, 5629 [1987] M. Lovejoy, D. D. Nelson Jr., D. J. Nesbitt, J. Chem. Phys. 87, 5621[1987]. c C. M. Lovejoy, D. D. Nelson Jr., D. J. Nesbitt, J. Chem. Phys. 89, 7180 [1988]. d E. J. Bohac, R. E. Miller, J. Chem. Phys. 98, 2304 [1993] b C.

126

TE06 15 min 2:50 QUANTUM SOLVATION: PATH INTEGRAL MONTE CARLO CALCULATIONS OF THE H2 -HF AND D2 -HF BINARY COMPLEXES IN LIQUID HELIUM DROPLETS DAVID T. MOORE, ROGER E. MILLER, Deptartment of Chemistry, University of North Carolina, Chapel Hill NC, 27599. Path Integral Monte Carlo (PIMC) simulations were performed for the H2 -HF complex in helium droplets. These simulations are based on the quantum-classical isomorphisma ; b and correctly incorporate quantum effects at the temperature of the droplets (0.37K). For comparison, simulations of the D2 -HF complex in helium droplets were also performed in order to compare the effects of the quantum helium solvent on the heavier D2 molecule. Interpretations of the experimental results (from the preceeding talk) based on these simulations will be discussed. a D. b D.

M. Ceperley, Rev. Mod. Phys. 67, 279 [1995] Chandler, P. G. Wolynes, J. Chem. Phys. 74, 4078 [1981]

Intermission

TE07 ABSOLUTE INTENSITIES MEASUREMENTS IN THE 4 WALLIS EFFECTS AND FORBIDDEN TRANSITIONS

+

10 min 3:30 12 5 BAND OF C2 H2 : ANALYSIS OF HERMAN-

J. VANDER AUWERA, Laboratoire de Chimie Physique Mol´eculaire C. P. 160/09, Universit´e Libre de Bruxelles, 50 avenue F. D. Roosevelt, B-1050 Brussels, Belgium. + We have measured absolute line intensities in two bands of 12 C2 H2 near 7:5m, namely the 4 + 5 (+ u ) 0(g ) and + 4 + 5 (
u ) 0(g ) bands, using Fourier transform spectroscopy with an accuracy estimated to be better than 2%. Using theoretical predictions from Watson a , the observation of the forbidden 4 + 5 (
u ) 0(+ g ) band and the Herman-Wallis behavior exhibited by its rotational lines were studied quantitatively in terms of two types of interactions affecting the + levels involved by the band: `-type resonance and Coriolis interaction. In the case of the 4 + 5 (+ u ) 0(g ) band, the influence of `-type resonance is also confirmed. We also attributed the intensity asymmetry observed between the R and P branches of that latter band to a Coriolis interaction with ` = 1 levels. We did not observe the 4 + 5 (u ) 0(+ g ) band, consisting only of a Q branch, in agreement with Watson’s prediction. a J.

K. G. Watson, J. Mol. Spectrosc. 188, 78 (1998)

127

TE08 10 min 3:42 PRESSURE BROADENING, PRESSURE SHIFTS AND ABSOLUTE LINE INTENSITIES MEASUREMENTS IN THE 1 + 33 BAND OF 12 C2 H2 F. HERREGODTS, M. HEPP, D. HURTMANS, J. VANDER AUWERA, and M. HERMAN, Laboratoire de Chimie Physique Mol´eculaire C. P. 160/09, Universit´e Libre de Bruxelles, 50 avenue F. D. Roosevelt, B-1050 Brussels, Belgium. We have used a Ti:Sa autoscan laser spectrometer to perform a detailed investigation of individual line profiles in the 1 . Pressure self- and Ar-induced broadening, narrowing and shift effects, as well as absolute intensities, were measured for lines with J 00 = 0 to 23, at room temperature and total pressures in the range from 10 to 800 mbar using a long White-type multiple-pass absorption cell. For the pressure shift measurements, an optoacoustic cell with a constant, low acetylene pressure provided simultaneous reference line position wavenumbers. The high-pressure spectra (p > 330 mbar) were fitted satisfactorily by a Voigt profile. Line narrowing, characterized by an underestimation of the Lorentz contribution to the Voigt profile, was observed for the low pressures range (p < 200 mbar), indicating the influence of molecular confinement. The two usual limit models (soft and hard collisions) were fitted to the observed line shapes to extract more precise information concerning the pressure broadening. Self- and Ar-induced lineshift parameters significantly different from the overall behavior in the band are unexpectedly observed for the R(17) and P (19) lines. This result is explained in terms of a different intermolecular behavior of the molecule in the upper J = 18 rotational level, attributed to an intramolecular Coriolis-type coupling with a nearby state tentatively assigned as containing important excitation in 5 , the cis-bending mode.

1 + 33 band of 12 C2 H2 , near 12676 cm

TE09 15 min 3:54 FTIR JET SPECTROSCOPY OF THE FUNDAMENTAL PARALLEL BANDS OF PERFLUOROCYCLOBUTANE IN THE MID-INFRARED THOMAS A. BLAKE, ROBERT L. SAMS, and STEVEN W. SHARPE, Pacific Northwest National Laboratory, P. O. Box 999, Mail Stop K8-88, 3020 Q Avenue, Richland, WA 99352 (PNNL is operated for the US Department of Energy by the Battelle Memorial Institute under contract DE-AC06-76RLO 1830). Rotationally resolved spectra have been obtained for five fundamental bands and associated hot bands for perfluorocyclobutane using a Bruker IFS 120HR Fourier transform infrared spectrometer interrogating a continuous slit jet expansion of a 10% c-C4 F8 -in-helium mixture. The rotational temperature of the expansion is approximately 10 K. The ring of perfluorocyclobutane is slightly puckered and the molecule has D 2d symmetry. The B 2 parallel bands at 1240:3 and 1292:6 cm 1 correspond to CF2 stretchs and have been assigned and fit with a rigid rotor, symmetric top Hamiltonian. The fundamental band at 1292:6 cm 1 has the following fit constants:  0 = 1292:56039(3) cm 1 , B 0 = 0:0354142(4) cm 1 , and B 00 = 0:0354367(4) cm 1 . The band at 1240:3 cm 1 correlates with an B 1g symmetry mode in planar c-C4 F8 and consequently has IR allowed transitions from the excited ring puckering states. Indeed, we observe that the transitions in this band are split into strong and weak components corresponding to transitions from the ground and first excited ring puckering states, respectively. The stronger component has the following fit constants:  0 = 1240:34858(4) cm 1 , B 0 = 0:0354192(7) cm 1 , and B 00 = 0:0354356(7) cm 1 ; and for the weaker component  0 = 1240:34674(5) cm 1 , B 0 = 0:0354188(9) cm 1 , and B 00 = 0:0354360(9) cm 1 . No K structure was observed in any of the parallel bands and attempts to fit distortion constants to these bands were unsuccessful. Rotationally resolved bands were also observed at 964:3 cm 1 (E ), 1223:5 cm 1 (B 2 ), and 1343:2 cm 1 (E ).

128

TE10 15 min 4:11 A COMBINED FREQUENCY ANALYSIS OF THE 3 , 9 , AND THE FAR INFRARED TORSIONAL SPECTRA OF ETHANE N. MOAZZEN-AHMADI, Department of Physics and Astronomy, University of Calgary, 2500 University Drive N.W., Calgary, Alberta, Canada, T2N 1N4. The lowest frequency nondegenerate fundamental band 3 of ethane is Raman active and centered near 992 cm 1 : A stimulated Raman spectrum of the Q branch for this band (at a resolution of 0:0055 cm 1 ) has been recorded by Bermejo et al.a The torsion-rotation branch with  = 3 is perturbed by over 1 cm 1 : The lowest frequency degenerate fundamental band 9 is infrared active and occurs in the 12-m region. A high resolution (0:0014 cm 1 ) Fourier transform spectrum of this band has been measured by Moazzen-Ahmadi el al.b The observed torsional splittings for this band are substantially larger than expected simply from the observed increase in the barrier height. Because of the proximity of the upper level (l = 1; K = 17;  = 0) in v9 = 1 with its interacting partner (v9 = 0; v4 = 3) a perturbation allowed band 34 has also been observed. We have carried out a combined frequency analysis of 3 , 9 ; and 34 bands together with the far infrared torsional spectra in the ground vibrational state (gs). A vibration-torsion-rotation Hamiltonian with 32 fitting parameters was used. Three interacting torsional stacks, one for each of the vibrational state, were considered. The large torsional splitting in the 9 band is attributed to Coriolis-like interations between the torsional stacks of gs and v9 = 1 whereas the large shift for the torsion-rotation branch with  = 3 in the 3 band is attributed to a Fermi-like interaction between the torsional stacks of gs and v3 = 1. The details of this analysis will be presented. a D. b N.

Bermejo, J. Santos, P. Cancio, J.M. Fernandez-Sanchez, and S. Montero, J. Chem. Phys. 97, 7055 (1992). Moazzen-Ahmadi, J. Schroderus, and A.R.W. McKellar, J. Chem. Phys. 111, 9609 (1999).

TE11 FUNDAMENTAL AND OVERTONE INTENSITIES FOR OH STRETCHING BANDS

15 min

4:28

K. R. LANGE, K. S. PLEGGE, N. P. WELLS, J. A. PHILLIPS, Department of Chemistry, University of Wisconsin - Eau Claire, Eau Claire, WI 54701. Integrated absorption intensities of OH stretching bands, from the fundamental through the third overtone, have been measured for vapor-phase methanol, ethanol, isopropanol, n-propanol, 1,1,1-trifluoroethanol, tertiary butanol, and nitric acid. Several trends apparent in these data will be discussed. For example, the fundamental OH band intensities are much more consistent than those in CH containing moleculesab . Furthermore, the overtone intensities are even more consistent, and appear to be essentially indentical for the second overtone, at least among the compounds examined thus far. Trends in the intensities as a function of excitation level will be modeled, and the dipole moment functions which result from this procedure will be compared to those obtained from molecular orbital calculations. a A. b G.

Amrein, H. Dubal, M. Lewerenz, and M. Quack, Chem. Phys. Lett. 112, 387 (1984). Longhi, G. Zerbi, L. Ricard, and S. Abbate, J. Chem. Phys. 88, 6733 (1988).

TE12 15 min SIMULTANEOUS VIBRATIONAL TRANSITIONS IN ABSORPTION SPECTRA OF BINARY SYSTEMS

4:45

A. AKHMEDJONOV, R. AKHMEDJONOV, and A. RASULOV, Samarkand State University, Samarkand, 703004, Uzbekistan. Frequencies, widths and bands intensities of the simultaneous transitions of the infrared absorption spectra in the gases mixtures and solutions N2, CO2, Br2 and I2 with CO2 and CS2 have been measured and calculated. In all experiments there is a conservations of integral coefficients of simultaneous transitions absorption bands in gas and liquid mixtures. It shows that the binary character of molecular interactions in condensed pahse is basic. We revealed the correlation parameters of the simultaneous transitions bands in IR absorption spectra and Raman Different scientific and practical applications of simultaneous transitions IR spectroscopy have been discussed.

129

TE13 15 min 5:02 SIMULTANEOUS TRANSITIONS IN IR ABSORPTION SPECTRA OF SYSTEM CAPABLE TO THE COMPLEX FORMATION A. AKHMEDJONOV, U. RAHMATULLAEV, and I. RUSTAMOV, Samarkand State University, Samarkand, 703004, Uzbekistan. We observed a number of simultaneous vibrational transitions in the absorption spectra of gas and liquid mixtures with HCl, CHCl3, CDCl3, H2O and some alcohols. Frequencies, widths and integral band intensities of the IR spectra have been measured. In approximation of pair electrostatic induction mechamism the absolute intensities of observed IR absorption band were calculated. In these calculations the models of intermolecular potentials of the Lennard-Johns (12:6) and Kihara were used. Important role of complex formation on intensity of simultaneous transitions bands was demonstrated.

130

TF. RADICALS AND IONS TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1009 McPHERSON LAB Chair: BOR-CHEN CHANG, National Central University, Chung-Li, Taiwan

TF01 LIF EXCITATION SPECTROSCOPY OF 3-PENTOXY AND TERT-PENTOXY RADICALS

15 min

1:30

C.J. WANG, W. DENG, L. G. SHEMESH, M. D. LILIEN, D. R. KATZ and T. S. DIBBLE , Department of Chemistry, State University of New York, College of Environmental Science and Forestry, Syracuse, NY 13210.. The laser induced fluorescence (LIF) excitation spectra of 3-pentoxy and tert-pentoxy radicals are obtained for the first time. The experiments were carried out in the wavelength range 345-400nm by laser photolysis of corresponding pentyl nitrites at 355nm. For 3-pentoxy, 15 vibronic bands were labled in three progressions with initial vibrational interval 5786 cm 1 corresponding C-O stretch mode. Two other unknown mode progressions have vibrational intervals of 59610 and 59010 cm 1 . The transition origin was tentatively assigned at 264375 cm 1 . For tert-pentoxy, the LIF spectrum consists 12 vibronic bands in three progressions. The C-O stretching vibration frequency and transition origin are derived to be 55110 and 2549110 cm 1 . The initial vibrational intervals of other two unknown modes are 58710 and 63110 cm 1 . New observations from LIF experiments on 10 additional large alkoxy radicals in the range from 335 to 400 nm are reported.

TF02 JET-COOLED VIBRONIC SPECTROSCOPY OF VARIOUS ALKOXY RADICALS

15 min

1:47

JEFFREY R. ATWELL, CHRISTOPHER C. CARTER, SANDHYA GOPALAKRISHNAN, BRIAN E. APPLEGATE, AND TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210. Recently we have obtained vibronically resolved spectra of some moderately large alkoxy radicals, including 1-propoxy, isopropoxy, 1-butoxy, 2-butoxy, and t-butoxy. The species were produced in the jet by XeF photolysis of the appropriate alkylnitrite. This work represents the first jet-cooled spectra of the butoxy species; previous excitation spectra of the larger alkoxies have been limited to only a couple of flow cell experiments.a ; b A parallel effort has generated good quality ab initio calculations for the alkoxy radicals to aid in the spectral analyses. The vibronic structure and analysis will be discussed including comparisons with the previous cell experiments. The present experiments are preliminary to ones that will obtain higher resolution, rotationally resolved spectra. a Wang b Mund

C.; Shemesh L. G.; Deng W.; Lilien M. D.; and Dibble T. S., J. Phys. Chem. A, 1999, 103, 8207. C.; Fockenberg C.; and Zellner R.; Ber. Bunsen-Ges., 1998, 102, 709.

131

TF03 FLASH PYROLYSIS IR LASER JET SPECTROSCOPY OF KETENE DERIVATIVES

15 min

2:04

R. J. LIVINGSTONE, Z. LIU and P. B. DAVIES, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom; N. R. HORE and D. K. RUSSELL, Department of Chemistry, University of Auckland, Private Bay 92019 Auckland 1, New Zealand. We have used the flash pyrolysis technique, introduced by Chen and co-workers a , to generate free radicals and other short lived species for diode laser absorption spectroscopy in a supersonic jet b . The flash pyrolysis technique has proved to be particularly useful for producing ketene derivatives and we have recorded the carbonyl antisymmetric stretching modes of chloroketene (ClHCCO), methyl ketene (CH3 HCCO) and propadienone (H2 C3 O). The 2 band of ClHCCO was measured between 2153 and 2161 cm 1 . The molecule was formed by pyrolysis of chloroacetyl chloride at 1500 K. Over 200 lines of 35 ClHCCO were fitted, fixing the ground state constants to the microwave values c . We obtained A=1.201028(64), B=0.100399(3) and C=0.092530(3) cm 1 and a band origin of 2 = 2157.19238(16) cm 1 . We have also measured many lines of methyl ketene and propadienone generated from propionyl chloride and acrylic anhydride respectively. Their analysis is currently in progress. a P.

Chen, S. D. Colson, W. A. Chupka and J. A. Berson, J. Phys. Chem., 90, 2319 (1986). Liu, R. J. Livingstone and P. B. Davies, Chem. Phys. Lett., 291 480 (1998). c M. C. L. Gerry, W. Lewis-Bevan and N. P. C. Westwood, J. Chem. Phys., 79 4655 (1983).

b Z.

TF04 15 min 2:21 RYDBERG STATES OF ALLYL RADICAL OBSERVED BY ONE- AND TWO-PHOTON RESONANT IONIZATION SPECTROSCOPY JEN-CHIEH WU, RUNHUA LI, JIA-LIN CHANG and YIT-TSONG CHEN, Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, and Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan. The vibronic spectrum of allyl radical (CH2 CHCH2 ) at 4.9-8.2 eV has been observed using 1+1 and 2+1 resonanceenhanced multiphoton ionization (REMPI) spectroscopy. The allyl radicals were produced in the nozzle of a supersonic jet ~ 12 A1 ( !3s), C~ 22 B1 ( !3px ) expansion by the pyrolysis of allyl iodide. The vibronic assignment for the congested B 2  ~ and D 1 B2 ( !n ) bands at 4.9-5.2 eV will be reexamined with aid of the calculated Franck-Condon factors, especially for the weaker transitions at >5.2 eV which were not identified in previous study.a Three new electronic bands are observed for the first time and assigned to the 32 B1 ( !3dxz ), 22 A2 ( !3dxy ) and 32 A1 ( !3pz ) Rydberg states based on the ab initio CI calculation.b The observed band origins (in eV) at 6.460 (32 B1 ), 6.607 (22 A2 ) and 7.605 (32 A1 ) are compared with the calculated vertical energies of 6.41, 6.62 and 7.55, respectively. Vibrational progressions with the gross spacings of 420 cm 1 are observed in the Rydberg states. The totally symmetric 6 CCC bending in the excited state is responsible ~ state.c for the observed progression as that reported in the B a D.

W. Minsek and P. Chen, J. Phys. Chem., 97, 13375 (1993). -K. Ha, H. Baumann and J. F. M. Oth, J. Chem. Phys., 85, 1438 (1986). c A. D. Sappey and J. C. Weisshaar, J. Phys. Chem., 91, 3731 (1987).

b T.

TF05 THE ZEKE SPECTRA OF C3 H3 and C3 H5

15 min

2:38

THOMAS GILBERT,INGO FISCHER and PETER CHEN, Laboratorium f. Organische Chemie, ETH Zurich, CH-8092 Zurich, Switzerland.. The high-resolution zero kinetic energy photoelectron spectra of two important hydrocarbon radicals, propargyl (C3 H3 ) and allyl (C3 H5 ), were measured using both non-resonant and resonant excitation schemes. Accurate values for the ionization energies and cationic vibrational frequencies could be derived from the recorded data. In addition, information on the intermediate state vibronic coupling in allyl was obtained. The spectra of both species seem to agree well with the FranckCondon principle.

132

Intermission TF06 15 min 3:10 ROVIBRONIC INTERACTIONS AND l-UNCOUPLING IN THE HIGH-RYDBERG STATES OF HCO CONVERGING TO THE (010) STATE OF THE CATION ¨ ERIC J. ZUCKERMAN, ROBERT J. FOLTYNOWICZ, JASON D. ROBINSON, HARTMUT G. HEDDERICH, and EDWARD R. GRANT, Department of Chemistry, Purdue University, West Lafayette, Indiana 47906. We report the ionization-detected absorption spectra of vibrationally autoionizing Rydberg states converging to the (010) level of HCO+ . Resonances are isolated by transitions from photoselected rotational levels in the + and  Renner-Teller components of the (010) band of the 3p 2  Rydberg state. We systematically compare spectra in order to characterize observed resonances in terms of the good total angular momentum quantum number, N . Rydberg analysis establishes the convergence of series to detailed cation-core rotational quantum numbers, N + . Interactions between Rydberg orbital and core rotational angular momentum are found to conform with a coupling intermediate between Hund’s cases (b) and (d). Splitting patterns further assign certain features according to predominant case (b) composition.

TF07 15 min 3:27 THE EFFECTS OF INCREASED VIBRATIONAL AMPLITUDE ON ROVIBRONIC INTERACTIONS AND lUNCOUPLING IN THE HIGH-RYDBERG STATES OF HCO ¨ ERIC J. ZUCKERMAN, ROBERT J. FOLTYNOWICZ, JASON D. ROBINSON, and EDWARD R. GRANT, Department of Chemistry, Purdue University, West Lafayette, Indiana 47906. A detailed analysis of the autionizing Rydberg states converging to the (010) level of HCO has characterized series of transitions in terms of the total angular momentum, as well as the cation-core rotational quantum number, N + , and a quantum defect, Æ . Experiments employing optical selection to isolate structure built on higher vibrational states of the core show many of the same series. Systematic trends in quantum defects with increased bending amplitude reflect the structure of underlying close-couplied excited electronic states.

TF08 15 min 3:44 VIBRATIONAL SPECTROSCOPY OF A TRANSIENT SPECIES THROUGH TIME-RESOLVED FOURIER TRANSFORM IR EMISSION SPECTROSCOPY: THE VINYL RADICAL L. LETENDRE, and D.-K. LIU, Department of Chemistry, University of Pennsylvania, Philadelphia PA 19104; C. D. PIBEL , Department of Chemistry, American University, 4400 Massachusetts Avenue NW, Washington, DC 20016; J. B. HALPERN, Department of Chemistry, Howard University, Washington, DC 20059; H.-L. DAI, Department of Chemistry, University of Pennsylvania, Philadelphia PA 19104. An approach for detecting the vibrational spectrum of transient species is demonstrated on the vinyl radical. Photodissociation of carefully chosen precursors at a selected photolysis wavelength produce highly vibrationally excited radicals. IR emission from these radicals is then measured by time-resolved Fourier Transform Spectroscopy with nanosecond time resolution. This technique has the advantage of probing a wide frequency range of the IR spectrum in a single experiment. Using this method, all 9 vibrational bands of the vinyl radical, generated from 4 different precursors, are obtained for the first time. The cyanovinyl radical has also been studied and previously unknown vibrational assignments were made.

133

TF09 15 min 4:01 DETECTION OF TWO ISOMERS OF THE CYANOVINYL RADICAL: H2 CCCN AND CHCHCN BY FTMW SPECTROSCOPY J. TANG, K. SEIKI, Y. SUMIYOSHI, Y. ENDO, Department of Basic Sciences, The University of Tokyo, Komaba, Tokyo 153-8902, Japan; and Y. OHSHIMA, Department of Chemistry, Kyoto University, Kyoto 606-8502, Japan. The cyanovinyl radical has been proposed to play important roles in the interstellar chemistry of neutral-neutral reactions and the combustion chemistry of heavy fuels. However, no spectroscopic study was available before. We have observed two isomers of this carbon chain form: H2 CCCN and CHCHCN in their X 2 A0 states with a Fourier transform microwave spectrometer, generating them in a pulsed-discharge nozzle with the CH3 CN/Ar or CH2 CHCN/Ar gas mixtures. The rotational constants from the observation are in good agreement with the values from ab initio calculations (RCCSD(T)/ccPVTZ) by one percent. The observed spectra of both isomers showed very complicated patterns due to the comparable order of magnitude for the spin-rotation interaction and the nuclear hyperfine interactions from the three nuclei H and N, which made the traditional way of assignment incapable. An approach of maximizing a cross-correlation between experimental and simulated spectra has been applied to the assignment of the massing spectra. Result and progress will be presented.

TF10 15 min 4:18 OBTAINING INFORMATION ON JAHN-TELLER ACTIVE SYSTEMS THROUGH ASYMMETRIC ISOTOPIC SUBSTITUTION: CASE OF CHD2 O AND CH2 DO METHOXY RADICALS ILIA J. KALINOVSKI, WAI Y. FAN, X. L. CHEN, C. BRADLEY MOORE, Chemical Sciences Division of the Lawrence Berkeley National Laboratory and Department of Chemistry, UC Berkeley, Berkeley 947201460, California, USA. As for vibrational analyses of molecules in non-degenerate electronic states, isotopic substitution can enhance the set of parameters determinable from vibrational spectra of Jahn-Teller active systems. In comparison with molecular systems in non-degenerate electronic states, the vibronic Hamiltonian of Jahn-Teller active systems includes additional parameters linear and higher-order Jahn-Teller coupling constants. Asymmetric isotopic substitution lowers the original vibrational symmetry of the problem, and thus, drastically modifies the observed vibrational spectrum. This modification allows determination of parameters of the vibronic Hamiltonian of Jahn-Teller active systems with greater confidence than is possible using the symmetric isotopomers alone. SEP spectra of CHD2 O and CH2 DO are presented and analysis of the patterns of spin-vibronic states is attempted. A spin-vibronic Hamiltonian is used that considers simultaneous effects of linear Jahn-Teller and spin-orbit interactions. Connections between the Jahn-Teller interaction parameters of the isotopomers are discussed. This work was supported by the Chemical Sciences Division of the U.S. Department of Energy under Contract No. DEAC03-76SF00098.

134

TF11 15 min 4:35 DETECTION AND CHARACTERIZATION OF ALKYL PEROXY RADICALS USING CAVITY RINGDOWN SPECTROSCOPY MICHAEL PUSHKARSKY, SERGEY J. ZALYUBOVSKY, AND TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210. Peroxy radicals form a class of important intermediates in oxidation chemistry. In recent years much effort has been put e 2 A00 -X e 2 A00 UV into the study of the kinetics of peroxy radicals largely via monitoring their broad and structureless B 2 2 0 00 e e absorption transition. The A A -X A electronic transition of the peroxies, residing in the near-IR region, has also been observeda , but due to the relative inaccessibility of the spectral region and the small cross-section has practically not been used for monitoring peroxy radicals. Cavity Ringdown Spectroscopy (CRDS), is a powerful technique for dealing with these difficulties. Moreover the value of obtaining the IR spectra would be significant for both detection capabilities and e2 A0 -X e 2 A00 electronic transition spectroscopic characterization of peroxy radicals. We have used CRDS to record the A in near-IR region for the methyl and ethyl peroxy radicals and their deuterated isotopomers in an ambient cell. Analysis of partially resolved rotational structure for the origin bands of the CH(D)3 O2 will be presented. An empirical value for the absorption cross-section for CH3 O2 was determined from the CRDS absorption and the rate of radical-radical recombination. a H.

E. Hunziker and H. R. Wendt, J. Chem. Phys. 64, 3488(1976)

TF12 15 min 4:52 LABORATORY DETECTION OF A MOLECULAR BAND COINCIDENT WITH THE DIFFUSE INTERSTELLAR BAND AT 4428 C. D. BALL, M. C. MCCARTHY, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 and Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138. ˚ closely centered on the strongest diffuse interstellar band at A strong molecular absorption band at 4429.27  0.04 A, ˚ has been found in a supersonic molecular beam among the products of a discharge through benzene and 4428.9  1.4 A, other hydrocarbons. This agreement in wavelength to a few parts in 104 strongly suggests a common carrier. The width of the laboratory band is significantly less than that of the interstellar band, but this difference may be the result of the very low rotational temperature in the supersonic beam relative to that of a weakly polar molecule in the diffuse interstellar gas (100-200 K). Deuterium substitution suggests a carrier with elemental formula Cx H5 , where 3x6. Several candidate carriers are discussed. TF13 VIBRONIC SPECTROSCOPY OF CHLOROBENZYL RADICALS IN THE VISIBLE REGION

15 min

5:09

SANG KUK LEE, SANG YOUL CHAE, Department of Chemistry, Pusan National University, Pusan, 609735, South Korea. The jet cooled chlorobenzyl radicals have been generated with a large amount of He carrier gas from chlorotoluenes using a modified Engelking-type nozzle in a corona excited supersonic expansion. The vibronic emission spectra of chlorobenzyl radicals have been recorded with a long-path monochromator in the visible region. The spectra exhibit wellresolved vibronic structure from which the vibrational mode frequencies in the ground electronic state have been accurately determined by comparing with those of ab initio calculation as well as those of LIF-DF spectra reported previously.

135

TG. ELECTRONIC (SMALL) TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1000 McPHERSON LAB Chair: DONG-SHENG YANG, University of Kentucky, Lexington, KY

TG01

15 min

1:30

XUV LASER PHOTOIONIZATION SPECTROSCOPY AT A RESOLUTION OF 0.008 CM 1 U. HOLLENSTEIN, G. C. L. PETRAGLIO, H. PALM, R. SEILER and F. MERKT, Laboratorium f¨ur Physikalische Chemie, Eidgen¨ossische Technische Hochschule, ETH-Zentrum, CH-8092 Zu¨ rich, Switzerland. A new broadly tunable (7-17 eV) narrow bandwidth (0.008 cm 1 ) VUV laser system is presented. The system has been used to record photoionization spectra of small molecules (N2 , CO) in the vicinity of their ionization threshold. At the high resolution detailed information can be extracted on the spectroscopic and dynamic properties of electronically excited states, in particular Rydberg states.

TG02 15 min 1:47 PERTURBATIONS: THE (MODERATELY) HARD WAY TO OBSERVE CORE-NONPENETRATING RYDBERG STATES JASON O. CLEVENGER, XING JIANG, CHRISTOPHER M. GITTINS, and ROBERT W. FIELD, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139a . Core-nonpenetrating Rydberg states can provide information about the multipole moments and polarizability of the molecular ion-core. Unfortunately, the nonpenetrating states are not nearly as gregarious as their core-penetrating cousins. The vast majority of known Rydberg states are core-penetrating, and are well characterized precisely because they form regular Rydberg series and have molecular constants very similar to those of the molecular-ion electronic ground state. Nonpenetrating states often appear in fragmentary form as pattern-breakers, borrowing intensity from the penetrating states. As pattern-breakers, they place an enormous burden on spectroscopists, who must assemble the fragments into l-complexes and distinguish the bona fide nonpenetrators from ”interlopers” (usually higher-v levels of lower-n penetrating series). CaF and CaCl have very similar electronic structures, but with two important differences: CaCl has a much lower dissociation energy than CaF and CaCl has two Cl isotopes. Vive la difference! a This

research is supported by NSF Grant CHE97-30852.

136

TG03 RYDBERG STATES OF CALCIUM MONOCHLORIDE

15 min

2:04

JASON O. CLEVENGER, XING JIANG, SERGEY I. PANOV, and ROBERT W. FIELD, Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139a . Experimental results from our continuing study of the Rydberg states of Calcium Monochloride will be presented. Previously we have characterized the quantum defects and predissociation mechanisms of core-penetrating 2 + states of CaCl in the n* = 3-7 region.a ; b Questions unanswered by this work propelled further studies of the low-n* region (n* = 3-5) by REMPI and ion-dip techniques, as this region is expected to be extensively predissociated by 2 + and 2  repulsive states. Interest in high-n* (n* > 15) Rydberg states of CaCl has also fueled further REMPI experiments near the first ionization threshold (48 491 cm 1 ). Studies of the low-n* region failed to reveal several predicted members of known core-penetrating 2 + Rydberg series (n* = 0.16, 0.49, 0.68 2 + and 0.30 2 ), while preliminary data for the high-n* region above the v + = 0 IP indicate the presence of vibrationally autoionizing Rydberg states converging to v + > 0 vibrational levels of the CaCl+ ion X 1 + state. Analysis is ongoing. a This

research is supported by NSF Grant CHE97-30852. Li, Y. Liu, D. B. Moss, C. M. Gittins, N. A. Gittins, and R. W. Field, J. Mol. Spec. 193, 403 (1999). b J. O. Clevenger, N. A. Harris, R. W. Field, J. Li, J. Mol. Spec. 193, 412 (1999). a J.

TG04 15 min 2:21 NONLINEAR ABSORPTION IN JET-COOLED NO2 BY COMBINING THE CRDS AND LIF TECHNIQUES ´ ´ Grenoble High MagSYLVAIN HEILLIETTE, ANTOINE DELON, REMY JOST and PATRICK DUPRE, netic Field Laboratory, CNRS-MPI, BP 166, 25 Rue des Martyrs 38042 GRENOBLE,Cedex 9, France. By combining the capabilities of a high-Q optical cavity with the ones of a supersonic jet (nozzle) expansion, we can get a powerful tool for probing weak absorbing molecular transitions or traces of contaminants (  5:10 10 =cm). Moreover, sensitive high resolution spectroscopy is obtained by combining the Cavity Ring Down Spectroscopy (CRDS) technique with single mode CW laser sources. In the red energy range, Ring Down times greater than 100 s can be easily obtained with an intracavity power which can reach 100 W near 800 nm. In such conditions, the usual BeerLambert law can be readily violated, revealing nonlinear absorptions (saturations) when the electrical dipolar transition momentum is high enough (like for the hot vibrational bands of the NO2 radical) i.e., non exponential decays are observed.a Furthermore, Lamb dips are observable if the intensity of the electromagnetic field trapped inside the cavity is large enough. Additionally, 2-photons absorption transitions are detected by observing the LIF signal accompanying the absorption. Two kinds of 2-photon transitions are observed: i) sharp sub-Doppler (laser limited) transitions corresponding to resonant absorption and appearing only when the energy of the 2-photon transition is lower than the dissociation threshold, ii) Doppler limited transitions corresponding to non resonant transitions and appearing without energy threshold conditions revealing a continuum of absorption. a D.

Romanini, P. Dupr´e and R. Jost, in Vibrational Spectroscopy 19, 93 (1999)

137

TG05 JET-COOLED NO2 SPECTRUM AROUND THE DISSOCIATION THRESHOLD D0

( 25128 cm

15 min 1)

2:38

´ ´ Grenoble High MagSYLVAIN HEILLIETTE, ANTOINE DELON, REMY JOST and PATRICK DUPRE, netic Field Laboratory, CNRS-MPI, BP 166, 25 Rue des Martyrs 38042 GRENOBLE, Cedex 9, France. The Cavity Ring Down Spectroscopy (CRDS) technique is a unique tool for probing non fluorescing absorbing molecular species. High resolution in achievable in the blue-UV energy region by intracavity frequency doubling a CW laser source (here a Ti:Sa) and by using a seeded supersonic jet (slit nozzle) expansion. The NO2 radical is known to strongly absorb in the blue energy range. However, if a LIF signal can be easily detected up to the dissociation threshold D0 (NO2 ! NO(2 1=2 ) + O(3 P2 )), above, a lack of fluorescence is observed which is typical of a photodissociation process. The usual techniques for level detection above the dissociation threshold (PHOFEX or Fluorescence Depletion Pumping, for example) are based on pulsed sources (laser bandwidth limited). At the opposite, the CW CRDS technique (residual Doppler width:  400 MHz) allows to probe resonances above the threshold without laser bandwidth limitation. Resonances, whose the width spreads from  0:055 cm 1 (corresponding to a dissociation time of  200 ps) just above D0 , to larger shapes ( 1 cm 1 ) without clear structure 10 cm 1 higher, are identified. TG06 15 min 2:55 ROTATIONAL TEMPERATURE MEASUREMENTS OF AN OPTICALLY PUMPED, VIBRATIONALLY EXCITED CARBON MONOXIDE-ARGON PLASMA USING SINGLE PHOTON LASER INDUCED FLUORESCENCE OF THE (v00 = 20)X1 + (v0 = 2)D1 + BAND R. J. LEIWEKE and W. R. LEMPERT, Nonequilibrium Thermodynamics Laboratory, Department of Mechanical Engineering and Department of Chemistry, The Ohio State University, Columbus, OH 43210.

TG07

15 min 3:12 3 3 NEW RESULTS ON THE LOWEST LYING ELECTRONICALLY EXCITED STATES A2 AND B2 OF OZONE SABINE F. DEPPE, ALES CHARVAT, UWE WACHSMUTH, and BERND ABEL, Institut f¨ur Physikalische Chemie der Universit¨at G¨ottingen, Tammannstr. 6, 37077 G¨ottingen, Germany. The three low lying excited triplet states 3 A2 , 3 B2 and 3 B1 may have an impact on the observed anomalies of ozone concerning recombination kinetics, heavy isotope enrichment, photochemistry and atmospheric chemistry. Transitions to two of them - 3 A2 and 3 B2 - have been measured by Intracavity Laser Absorption Spectroscopy (ICLAS). In the former case single resolved rovibrational lines belonging to the (000) and (010) vibrational levels could be assigned, whereas in the latter case only broad absorption features are observed. The analysis has been performed by using an Hamiltonian explicitly taking into account spin-rotation and spin-spin coupling. The ozone molecule seems to follow a case (B) coupling behaviour. In the case of 3 B2 band contour simulations using the same formalism have been compared with the measured band contour of the considerably broadened spectrum. From this approach average life times in the order of 1-10 ps have been estimated. The obtained molecular parameters are in good agreement with predictions from ab initio calculations.

138

Intermission

TG08 15 min 3:45 CALCULATING FRANCK-CONDON FACTORS FOR TRANSITIONS FROM LINEAR TO BENT STATES: APPLICATION TO THE ELECTRONIC SPECTRUM OF DIACETYLENE PAUL R. WINTER and TIMOTHY S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907; KEVIN K. LEHMANN, Department of Chemistry, Princeton University, Princeton, NJ 08544. Expressions will be presented for calculating Franck-Condon factors in the harmonic approximation for transitions from a linear ground state to a bent excited state. These expressions are similar to those published previously by Doktorov et. al.a for the case where the number of modes does not change between the two states. The derivation of these equations will be briefly discussed. They will be applied to several test cases, including electronic transitions in diacetylene, C 4 H2 . a J.

Mol. Spec., 64, 302-326 (1977).

TG09 e 2A THE X

1 TOGETHER

15 min 4:02 2 Ae B2 CONICAL INTERSECTION IN NO2 , OR HOW EXPERIMENTS AND THEORY INTERPLAY

´ ´ PATRICE THEULE, ´ ANTOINE DELON, Grenoble High Magnetic Field REMY JOST, PATRICK DUPRE, Laboratory, CNRS-MPI, BP 166, 25 Rue des Martyrs 38042 GRENOBLE, Cedex 9, France; MARCEL JACON, GSMA, UFR Sciences, BP 1037, 51687 REIMS Cedex 2, France. We present a comparison between experimental results (vibronic energies, absorption and LIDFS intensity ratios, rotational constants) and ab-initio calculations (diabatic and adiabatic energies, vibronic matrix elements). The three main inputs e 2 A1 Ae 2 B2 conical intersection are: i) the diabatic levels of the Xe 2 A1 state (i.e., the required in the analysis of the X e 2 A1 observed by LIDFS), ii) the diabatic levels of the A e 2 B2 complete set of approximatively 200 low lying levels of the X state (they are approximately predicted by the ab-initio calculations), iii) the matrix elements of the vibronic interaction, V12 , between the Xe 2 A1 and Ae 2 B2 electronic states. The validity of the simplified form proposed for V12 , namely “Q3 ”, will be discussed. The comparison allows to assign some observed vibronic levels, which in return can be used to improve some parameters of the initial ab-initio PESurfaces. Up to now, our analysis is limited to the four lowest polyads of the Ae 2 B2 state ranging from 9700 cm 1 to 12300 cm 1 : At higher energy the interactions are stronger, leading to vibronic chaos above  17000 cm 1 :

139

TG10 THE NEAR IR BULK and JET-COOLED NO2 SPECTRA by FTS, ICLAS, CRDS and LIF

15 min

4:19

´ ´ ANTOINE DELON, SYLVAIN HEILLIETTE, PATRICE THEULE, ´ REMY JOST, PATRICK DUPRE, Grenoble High Magnetic Field Laboratory, CNRS-MPI, BP 166, 25 Rue des Martyrs 38042 GRENOBLE, Cedex 9, France; ALAIN CAMPARGUE, GABRIELE WEIRAUCH, Laboratoire de Spectrom´etrie Physique, ` CNRS-Universit´e J. Fourier de Grenoble, BP 87, 38402 SAINT MARTIN D’HERES Cedex, France; JOHANNES ORPHAL, Laboratoire de Photophysique Mol´eculaire, CNRS-Universit´e Paris-Sud, Bˆat. 350, Centre d’Orsay, 91405 ORSAY Cedex, France; JOHN P. BURROWS, SABINE DREHER, Suzanne Voigt Institute of Environmental Physics and Remote-Sensing University of Bremen, PO Box 330440, 28334 BREMEN, Germany. e 2 A1 A e 2 B2 conical intersection in NO2 we have extensively studied its near In order to characterize experimentally the X IR spectrum, both in a bulk cell and in a slit jet expansion. The advantages and disadvantages of the four techniques (FTS, ICLAS, CRDS, LIF) will be briefly summarized and there performances compared. Actually, only the slit jet spectra are analyzable, the room temperature spectrum being highly congested. More than 100 vibronic levels belonging to the 2 B2 e 2 B2 symmetry have been observed by absorption from 10800 to 13900 cm 1 whereas only 15 vibrational levels of the A 2 2 e e state (bright levels) are expected in that range. The X A1 A B2 vibronic interactions strongly mix the (dark) set of Xe 2 A1 levels (about 85 levels belonging to the 2 B2 symmetry) with the set of 15 Ae 2 B2 bright levels. In addition, numerous hot bands have also been observed in that range. Most of these vibronic levels have an irregular rotational structure, even if most of the K -subbands seem almost regular. This results from the combination of large energy differences between interacting levels and large matrix elements leading to smoothly varying mixing coefficients in each K stack. The iterative comparison of the band origins, intensities and rotational constants with those predicted by a model Hamiltonian is the clue of the understanding of the NO2 conical intersection.

TG11 HYPERFINE EFFECTS IN MAGNETIC ROTATION SPECTROSCOPY

15 min

4:36

CHRIS BOONE, Chemistry Department, University of Waterloo, Waterloo, Ontario, Canada, N2L 3G1. For magnetic rotation spectroscopy studies of diatomic molecules, strong signals occur for transitions involving electronic states with a significant component of electronic magnetic moment along the internuclear axis. Such electronic states are also candidates for large magnetic hyperfine effects. For transitions involving low values of J, it is therefore often difficult to perform a comprehensive analysis of magnetic rotation signals without taking hyperfine effects into consideration, even for Doppler-limited studies. Furthermore, there are contributions to the magnetic rotation signal that arise from interactions induced by the magnetic field between hyperfine levels. These unusual and interesting contributions to the magnetic rotation signal will be discussed. Examples will be given from a recent Doppler-limited magnetic rotation study of the 79 A3 1u –X1 + g system of Br2 , where hyperfine effects produced structure in the signals for transitions involving low values of J.

140

TG12

15 min

4:53 DOPPLER-FREE HIGH RESOLUTION SPECTRAL ATLAS OF IODINE MOLECULE 15,000 TO 19,000 CM 1 H. KATO, S. KASAHARA, M. MISONO, Department of Chemistry, Faculty of Science, Kobe University, 657-8501 Kobe, Japan; M. BABA, Faculty of Integrated Human Studies, Kyoto University, 606-8501 Kyoto, Japan. A new accurate spectral atlas with the Doppler-free spectrum of I2 from 15,000 to 19,000 cm 1 has been made up. Hyperfine lines were resolved using Doppler-free saturation spectroscopy with a single-mode ring dye laser (Coherent 899-29). The spectrum has been recorded together with frequency marks of an etalon. The cavity length of the etalon was stabilized by YAG laser light of which the frequency was locked to a certain hyperfine line of I2 . These frequency marks were calibrated with the precise transition wavenumbers of several standard lines. The absolute transition wavenumber of each observed hyperfine line can be determined by comparing the spectrum and the frequency marks in this atlas. The error is less than 0.00015 cm 1 , which is exceedingly better than the current atlas with the Doppler-limited spectrum.a The new atlas is essential for modern ultrahigh resolution molecular spectroscopy. The accurate transition wavenumbers of the spectral lines are important not only to obtain the accurate molecular constants but also to analyze the energy shifts by perturbation which induces excited state dynamics such as predissociation, intersystem crossing, intramolecular vibrational redistribution, and so on. This new atlas is now in press and will be released soon with the CD-ROM data. b a S.

Gerstenkorn and P. Luc, Atlas du Spectre d’Absorption de la Mol´ecule d’Iode entre 14800-20000 cm 1 , CNRS, Paris, 1978. by the propulsive committee of Photoscience :Research for the Future of Japan Society for the Promotion of Science (JSPS).

b This work was promoted

141

TH. MICROWAVE TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1015 McPHERSON LAB Chair: SCOTT DAVIS, NIST, Gaithersburg, MD

TH01 COMPARISON OF He AND H2 PRESSURE BROADENING OF NH3 FROM 15 TO 40 K

15 min

1:30

D. R. WILLEY, R. E. TIMLIN, M. DERAMO, P. L. PONDILLO, D. M. WESOLEK AND R. W. WIG, Department of Physics, Allegheny College, Meadville, PA 16335. Pressure broadening of the (J, K) = (1, 1), (2, 2) and (3, 3) inversion transitions of NH3 was measured using normal- H2 as the broadening agent at kinetic temperatures of 15 to 40 K. Measurements were taken in a quasi equilibrium cell using the collisional cooling technique. H2 pressure broadening cross sections were compared to low temperature He pressure broadening of the same transitions and found to be from 2.5 to 8 times larger than corresponding He cross sections. Measured normal H2 and He cross sections were also compared to calculated J = 0, para- H 2 cross sections. Preliminary experimental results for broadening by para- H2 will also be presented.

TH02 THE ROTATIONAL TORSIONAL SPECTRUM OF THE 5 /29 DYAD OF NITRIC ACID

15 min

1:47

DOUGLAS T. PETKIE, Department of Physics, Ohio Northern University, Ada, OH 45810; THOMAS M. GOYETTE, University of Massachusetts, Submillimeter Technology Lab, 175 Cabot Street, Lowell, Massachusetts, 01854; SIEGHARD ALBERT, Laboratorium f¨ur Physikalische Chemie, ETH Z¨urich, CH-8092 Z¨urich Switzerland; PAUL HELMINGER, Department of Physics, University of South Alabama, Mobile, AL 36688; REBECCA A. H. BUTLER and FRANK C. DE LUCIA, Department of Physics, The Ohio State University, 174 West 18th Avenue, Columbus, OH 43210-1106. The measurements and analysis of the millimeter/submillimeter transitions of the 5 /29 dyad of nitric acid have been extended from the symmetric topa into the asymmetric top limit. The analysis involves an IAM approach and includes the first term of a Fourier series expansion, cos(Ka ), for several elements of the Watson-type Hamiltonian. The analysis includes over 2300 transitions between 90-700 GHz that have been fit to a rms deviation of 97 kHz. The analysis also reproduces the published infrared line positions. Because of the strong Fermi resonance between the two vibrational states, the labeling of the torsional rotational energy levels can become ambiguous when the torsional and asymmetric splittings are similar. The analysis and schemes to deal with the labeling problem will be discussed. a Thomas

M. Goyette, Lee C. Oesterling, Douglas T. Petkie, Randy A. Booker, Paul Helminger, and Frank C. De Lucia, J. Mol. Spectrosc. 175, 395-410 (1996).

142

TH03 MICROWAVE INVESTIGATION OF SULFURIC ACID MONOHYDRATE

15 min

2:04

D. L. FIACCO, S. W. HUNT, and K. R. LEOPOLD, Department of Chemistry, University of Minnesota, Minneapolis, MN 55455. We report the first microwave spectroscopic investigation of the 1:1 complex of H2 O-H2 SO4 and several of its deuterated and 18 O containing isotopomers. The complex is prepared in situ via reaction of water and SO3 using a co-injection source in which H2 O vapor is introduced into the early stages of an Ar + SO3 expansion. Both a- and c- type spectra for fourteen isotopomers have been measured and are consistent in all cases with that of a near-prolate rotor with appreciable dipole moment components along the a- and c- inertial axes. The spectra of the isotopomers containing H2 16 O are complicated by internal motion of the water unit affecting both the a-type K 1 = 0 and several of the c-type transitions. The possible internal motions giving rise to the observed spectral splittings as well as the ground state structural parameters of the H2 O-H2 SO4 complex will be discussed and compared to recent DFT calculations.a ; b a S. b H.

Re, Y. Osamura, K. Morokuma, J. Phys. Chem. A 103, 3535 (1999). Arstila, K. Laasonen, A. Laaksonen, J. Chem. Phys. 108, 1031 (1998).

TH04 10 min 2:21 THE SUBMILLIMETER-WAVE SPECTRUM OF TRANS- AND CIS-CROTONONITRILE (CH3 CH=CHCN) BRIAN J. DROUIN AND JOHN C. PEARSON, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099. The ground state rotational spectrum and ground state rotational torsional spectrum of trans- and cis-crotononitrile are further characterized in the 270-480 GHz frequency range. The A-E splittings due to methyl internal rotation in transcrotononitrilea are not observed in the sub-millimeter spectrum which has been assigned and fit to a semi-rigid rotor Hamiltonian in agreement with previous workb . For cis-crotononitrile over 380 transitions are now assigned to this conformation, twice the number previously reported. Internal rotation splittings are observed throughout the a R branches and have been assigned for J > 30. The A-E spectrum fits reasonably well in an internal axis system, but strong correlation between Dab and the rotational constants indicates that a rotated internal axis system may suit the data better. a M.

Suzuki and K. Kozima, J. Mol. Spec. 33, 407-413 (1970); S. L. Hsu and W. H. Flygare, J. Mol. Spec. 37, 92-99 (1971). Lesarri, J. Cosleou, X. Li, G. Wlodarczak and J. Demaison, J. Mol. Spec. 172, 520-535 (1995).

b A.G.

TH05 THE PURE ROTATIONAL SPECTRA OF LANTHANUM MONOHALIDES

15 min

2:33

DARYL S. RUBINOFF, COREY J. EVANS and MICHAEL C. L. GERRY, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B. C., Canada, V6T 1Z1. The pure rotational spectra of the X 1 + ground states of all lanthanum monohalides have been measured using a pulsed-jet cavity Fourier microwave spectrometer in the range of 5-18 GHz. The molecules were prepared by ablating solid La with the second harmonic of a pulsed Nd:YAG laser and allowing the vapour to react with SF6 , Cl2 , Br2 or CH3 I precursor present as 0.01% in an Ar carrier gas. These are the first reported observations of any kind for lanthanum monobromide, and the first measurements of the pure rotational spectra of all species. Equilibrium geometries, vibrational wavenumbers and dissociation energies have been determined for all species. Nuclear quadrupole constants and nuclear spin-rotation coupling constants are also reported for both La and X (X=F, Cl, Br, I) and will be discussed.

143

TH06 15 min 2:50 MICROWAVE SPECTRA AND MOLECULAR STRUCTURE OF ACETYLENEMETHYLDIOXORHENIUM, A RHENIUM METALACYCLOPROPENEa STEPHEN KUKOLICH, BRIAN DROUIN, OLIVER INDRIS AND JENNIFER DANNEMILLER, Department of Chemistry, University of Arizona, Tucson, AZ 85721 (Present Address for B. Drouin: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109); JOCHEN ZOLLER and WOLFGANG HERRMANN, Anorganisch-Chemisches Institut der Technischen Universit a¨ t M¨unchen, Lichtenbergstrasse 4, D-85747 Garching bei Mu¨ nchen, Germany. The molecular structure for ((2 -acetylene)methyldioxorhenium (ACMDO) was H obtained by measuring and analysing the rotational spectra for 14 isotopomers. H H This appears to be the first gas-phase measurement for a rhenium metalacycloC propene, and the first structural data on this compound. This complex is closely H related to reaction intermediates in methyltrioxorhenium(MTO) and OsO4 catalC ysed oxidation reactions. These reactions are very important in industrial chemical production and for syntheses of chiral products. Only a few alkyne complexes O Re C of transition metals in high oxidation states are known and even fewer have been O structurally characterized. The microwave spectra were measured in the 4-11 H GHz range using a Flygare-Balle-type pulsed-beam microwave spectrometer. Rotational constants and rhenium quadrupole coupling tensors were obtained for all isotopomers. The acetylene ligand structure is modified and exhibits partial sp2 hybridization. The C-C bond length ˚ . The H-C-C interbond angles are reduced from 180Æ to 141Æ , and 152Æ . The quadrupole ˚ to 1.29A is increased by 0.08A splitting patterns and systematic changes in the quadrupole coupling tensors were very helpful in making positive assignments. a Supported

by THE NATIONAL SCIENCE FOUNDATION

TH07 15 min 3:07 EXTENSION OF TIME-RESOLVED DOUBLE RESONANCE STUDIES OF ROTATIONAL ENERGY TRANSFER TO AN OBLATE SYMMETRIC ROTOR MATTHEW M. BEAKY, Department of Physics, Duke University, Durham, NC 27708; DAVID D. SKATRUD, Physics Division, U.S. Army Research Office, RTP, NC 27709. Time-resolved double resonance spectroscopy is a powerful technique for studying intramolecular energy transfer mechanisms. Previous studies of rotational energy transfer in the prolate symmetric tops CH3 F and CH3 Cl have culminated in a quantitative and predictive model for rovibrational relaxation in these molecules which reduces the inherent complexity of the problem to only a small number of adjustable parameters. In the oblate symmetric top CDF3 , the spacing between K levels is much closer than the spacing between J levels, while for CH3 F and CH3 Cl the opposite is true. The goal of the current study is to understand exactly what effect this has on the relative importance of the pathways for rovibrational relaxation in CDF3 , because it can provide a stringent test both of the existing model and of our current state of understanding of energy transfer mechanisms in polyatomic molecules. Recent experimental results will be presented.

Intermission

144

TH08 15 min 3:40 SUBMILLIMETER WAVE ABSORPTION SPECTROSCOPY OF PSEUDOROTATIONAL TRANSITIONS IN TETRAHYDROFURAN DMITRY G. MELNIK, SANDHYA GOPALAKRISHNAN, TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210; and FRANK C. DE LUCIA, The Ohio State University, Dept. of Physics, Microwave Laboratory, 174 W. 18th Avenue, Columbus OH 43210. The c-type rotational structure belonging to the n = 1 ! n = 2 pseudorotational transition in tetrahydrofuran (THF) has been observed in the region of 185-326 GHz. The transitions have been observed using a pulsed jet fast scan absorption spectrometera . The apparatus incorporates a free running backward wave oscillator (BWO) and utilizes a technique which is an extension of FASSST spectroscopy to a pulsed jet environment. A suitable model to fit the available spetroscopic data along with the assignment of the observed pseudorotational transitions is discussed, and the analysis of the experimental data combined with data obtained previouslyb is presented. S.Gopalakrishnan, T.A.Miller, and F.C.De Lucia, 54th International Symposium on Molecular Spectroscopy Meyer, J. C. L´opez, J. L. Alonso, S. Melandri, P. G. Favero, and W. Caminati, J. Chem. Phys. 111, 7871, (1999)

a D.Melnik, b R.

TH09 ROTATIONAL SPECTROSCOPY TETRAHYDROFURAN

AND

RING-PUCKERING

CONFORMATION

OF

15 min 3:57 3-HYDROXY-

RICHARD J. LAVRICH, RACHELE L. RHEA, JAMES W. McCARGAR, and MICHAEL J. TUBERGEN, Department of Chemistry, Kent State University, Kent, OH 44242. The ring puckering conformation of 3-hydroxytetrahydrofuran, a five-membered heterocyclic ring, has been determined from rotational spectroscopy. Rotational constants for the normal isotopomer are A = 5581.8230 (7), B = 3638.8316 (7), and C = 2924.7410 (7) MHz; rotational spectra were also recorded for four 13 C isotopic species in natural abundance. The best fit structure is a C40 endo conformation with an intramolecular hydrogen bond from the hydroxyl to the ring oxygen. Projections of the dipole moment on the inertial axes, a = 0.956 (1) D, b = 0.875 (2) D, and c = 1.050 (2) D, were determined from Stark effect measurements. The experimental structure is nearly identical to the lowest energy ab initio conformation (MP2/6-31+G**).

TH10 15 min 4:14 VAN DER WAALS COMPLEXES OF 3-HYDROXYTETRAHYDROFURAN: 3-HYDROXYTETRAHYDROFURANH2 O AND 3-HYDROXYTETRAHYDROFURAN-Ar RICHARD J. LAVRICH, CHARLES R. TOROK, and MICHAEL J. TUBERGEN, Department of Chemistry, Kent State University, Kent, OH 44242. Microwave spectra have been measured for the most abundant isotopic species of two van der Waals complexes of 3hydroxytetrahydrofuran: 3-hydroxytetrahydrofuran-H2 O and 3-hydroxytetrahydrofuran-Ar. For the H2 O complex the fitted rotational constants suggest that the water molecule forms a double hydrogen bond with the furan by donating a hydrogen bond to the ring oxygen and accepting a hydrogen bond from the hydroxyl group. Preliminary Stark effect experiments have been performed, yielding a = 1.2 (3), b = 1.82 (1), and c = 0.7 (4) D. The rotational constants of the argon complex are fit best by a model that has the Ar atom situated on the same side of the ring as the hydroxyl group.

145

TH11 MICROWAVE INVESTIGATION OF FOR THIS MOLECULE

15 min 4:31 CIS; T RANS -1,4-DIFLUOROBUTADIENE AND A PARTIAL STRUCTURE

RICHARD J. LAVRICH and MICHAEL J. TUBERGEN, Department of Chemistry, Kent State University, Kent, OH 44242; NORMAN C. CRAIG and CATHERINE M. OERTEL, Department of Chemistry, Oberlin College, Oberlin, OH 44074. The cis,trans isomer of 1,4-difluorobutadiene has been investigated with a pulsed-beam, Fourier transform microwave spectrometer in the spectral range of 5-17 GHz. This molecule is a near-symmetric top with  = -0.9744. Sufficient btype and a-type transitions for the parent species have been observed to fit a Watson-type Hamiltonian with A = 12,982.1, B = 1467.82, and C = 1318.64 MHz. From a Stark-effect study of three transitions of the parent, the two components of the dipole moment have been determined as b = 2.213 (5) D and a = 0.660 (4) D. Fewer transitions have been observed for each of the four different 13 C isotopomers in natural abundance. Fitting Hamiltonians for the 13 C isotopomers has required the transfer of some centrifugal distortion constants from the parent. Cartesian coordinates and geometric parameters for the carbon-atom backbone have been found by the substitution method. All the bond angles and bond lengths differ in this planar molecule. Thus, its complete structure is an eighteen-parameter problem. Partially deuterated material has been prepared by isotopic exchange in basic D2 O. From a study of this mixture a full structure should be determinable.

TH12 10 min 4:48 ROTATIONAL SPECTRA AND INTERNAL ROTATION OF 1,1,1,2,2-PENTAFLUOROPROPRANE AND 2,2,2TRIFLUOROETHYLMETHYLETHER N. SAKAKIBARA, K. FUCHIGAMI, Y. TATAMITANI, T. OGATA, Department of Chemistry, Faculty of Science, Shizuoka University, Shizuoka, Japan 422-8529. The rotational spectra of CF3 CF2 CH3 and trans - and gauche -CF3 CH2 OCH3 , constitute alternative compounds to the CFCs, have been studied by microwave spectroscopy. The spectra were measured using Stark modulation and Fouriertransform microwave spectrometers at Shizuoka University. Both molecules exhibited the spectrum due to many excited states of the CF3 torsion. Accurate rotational constants and quartic centrifugal distortion constants have been obtained for the ground and torsional excited states up to v = 3. The barrier heights to internal rotation of the CF3 top have been determined for these molecules. Reasonable molecular structures have been derived from the observed rotational constants and were compared with those of ab initio calculations of GAUSSIAN MP2/6-311G** level.

TH13 GAS PHASE STRUCTURE OF TRIFLUOROACETYL PEROXYNITRATE.

10 min

5:00

ANGELIKA HERMANN, JAN NIEMEYER, HANS-GEORG MACK, DINES CHRISTEN, and HEINZ OBERHAMMER, Institute of Physical and Theoretical Chemistry, University of Tu¨ bingen, Germany; HELGE ¨ WILLNER, Institute of Synthetic Chemistry, University of Duisburg, Germany; MARTIN SCHAFER and ALFRED BAUDER, Laboratory of Physical Chemistry, ETH, Z¨urich, Switzerland. The molecular structure and conformational properties of trifluoroacetyl peroxynitrate, FPAN, CF3 C(O)OONO2 , were investigated in the gas phase by electron diffraction, microwave spectroscopy and quantum chemical methods. All experimental and theoretical methods show the syn conformer (C=O bond of the acetyl group syn to O-O bond) to be strongly ˚ which correlates with the low predominant relative to the anti conformer. The O-N bond is extremely long (1.526 (10) A), ˚ is bond energy and the easy formation of CF3 C(O)OO and NO2 radicals in the atmosphere. The O-O bond (1.408 (8) A) ˚ and the C-O-O-N dihedral angle is close to 85o . shorter than that in hydrogen peroxide (1.464 A)

146

TH14 10 min 5:12 THE MICROWAVE SPECTRUM OF 1,2,4-TRIAZINE AND THE ROTATIONAL CONSTANTS OBTAINED FROM A SIMULTANEOUS ANALYSIS OF MICROWAVE GROUND STATE AND HIGH RESOLUTION IR-TRANSITIONS. DINES CHRISTEN, Institute of Physical and Theoretical Chemistry, University of T¨ubingen, Germany; MICHAEL H. PALMER, Department of Chemistry, University of Edinburgh, Scotland, UK; FLEMMING HEGELUND, Department of Chemistry, Aarhus University, Denmark. The microwave spectrum of 1,2,4-triazine has been recorded in the Ku- and Ka-bands using a conventional stark spectrometer. The low-J lines appeared close to the frequencies predicted for the ground state from the high resolution FTIR-studiesa , but to secure a correct assignment of higher J Q-branch transitions, a microwave-microwave double resonance experiment was done for a few pairs of transitions sharing a common level. 145 transitions were recorded with Jmax = 42, Ka;max = 33, and Kc;max = 11. A simultaneous fit to MW pure rotational transitions and to the rotational structure of selected IR-bands led to a determination of rotational and all 5 quartic centrifugal distortion constants. a Palmer, Maier, Hegelund, and Newnham, J. Mol. Spectrossc. 192, 331, (1998) and Bach, Hegelund, Beukes, Nicolaisen, and Palmer, J. Mol. Spectrosc. 198, (1999)

TH15 PROGRESS REPORT ON THE STUDY OF THE AMINO AMIDE VALINAMIDE

10 min

5:24

RICHARD J. LAVRICH, CHARLES R. TOROK, and MICHAEL J. TUBERGEN, Department of Chemistry, Kent State University, Kent, OH 44242. We have continued our study of the amide derivatives of amino acids by measuring the rotational spectrum of the most abundant isotopic species of valinamide. Because of its isopropyl side chain, valinamide has greater conformational flexibility than alaninamide. The rotational transitions are split into many nuclear quadrupole hyperfine components by the two 14 N nuclei; preliminary estimates for the line centers were used in fitting the 23 a-, b-, and c-type transitions, resulting in rotational constants of A = 3019.10 (4), B = 1472.97 (2), and C = 1252.48 (2) MHz. A comparison of the experimental data with ab initio calculations will be presented.

147

TI. THEORY TUESDAY, JUNE 13, 2000 – 1:30 PM Room: 1005 SMITH LAB Chair: PETER BOTSCHWINA, Universit¨at G¨ottingen, G¨ottingen, Germany

TI01 15 min 1:30 K-SCRAMBLING IN A NEAR-SYMMETRIC-TOP MOLECULE CONTAINING AN EXCITED NON-COAXIAL INTERNAL ROTOR JUAN ORTIGOSO, Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cient´ıficas, Serrano 121, 28006 Madrid, Spain; JON T. HOUGEN, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441. Classical trajectories on rotational energy surfaces and coherent-state quantum projections have been used to study an asymmetric-top molecule containing a freely rotating internal symmetric top whose symmetry axis is not coincident with a principal axis of the molecule. Stationary points on the rotational energy surface, which strongly influence the trajectories, increase in number from two to four to six as J=n increases from zero to infinity (where J is the total and n is the freeinternal-rotor angular momentum). For some J=n values trajectories can arise which sample a large fraction of K values (where K is the z -axis projection of J ), corresponding in quantum wavefunctions to extensive K -mixing in the symmetrictop basis set jJ; K i. When such mixing cannot be made small for any choice of z axis we call it K -scrambling. For typical values of the torsion-rotation coupling parameter , rotational eigenfunctions for given J and torsional state turn out to be quite different from eigenfunctions for the same J in some other torsional state. Nonzero rotational overlap integrals are then distributed among many rotational functions for each (n; n0 ) pair, which may in turn contribute to internal rotation enhancement of intramolecular vibrational energy redistribution. We have also examined near-free-rotor levels of our test molecule acetaldehyde, which arise for excitation of ten or more quanta of methyl group torsion, and find that barrier effects do not change the qualitative picture obtained from the free-rotor treatment.

TI02 IVR SCALING OF THE INTERNAL ROTOR

15 min

1:47

RYAN PEARMAN and MARTIN GRUEBELE, Beckman Institute for Advanced Science and Technology and Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801. It is widely known that the presence of an internal rotation (eg methyl rotor) will enhance IVR rate for local modes in close proximity. We utilize a simple 2-D model to demonstrate the enhancement in IVR between a coupled Morse Oscillator/Hindered Rotor system. In particular, we show that this enhancement is due to a peak in the effective density of states when the energy in the rotor degree of freedom lies at or just above the barrier height. We extend the model to show similar behavior for the case of methanol.

148

TI03 15 min DYNAMICAL STUDY OF TRIMETHYLAMINE BY MEANS OF THE NON-RIGID GROUP THEORY

2:04

Y. G. SMEYERS, Instituto de Estructura de la Materia, C.S.I.C, Serrano 113-bis, 28006-Madrid, SPAIN. ; and M. VILLA, Departamento de Quimica, Universidad Autonoma Metropolitana - I., 09340, D. F., MEXICO.. In this communication, the character table for the triple equivalent methyl rotation is determined from the Non-RigidMolecule-Group theory (NRG), in which the dynamical symmetry operations are defined as physical operations. This Group of order 648 is shown to be a product of two subgroups, the G324 corresponding to planar trimethylamine and the pyramidal inversion subgroup. For this purpose, the structure of the NRG of planar trimethylamine is first deduced, i.e., the number of classes, irreducible representions as well as their dimensions. Finally, guidelines are given to deduce systematically the symmetry eigenvectors developed on the basis of quadrupole products of trigonomeetric functions. TI04 15 min 2:21 INFLUENCE OF THE VIBRATIONAL ZERO POINT CORRECTION ON THE AMINE INVERSION BARRIER AND THE FIR SPECTRUM OF METHYLAMINE Y. G. SMEYERS, Instituto de Estructura de la Materia, C.S.I.C, Serrano 113-bis, 28006-Madrid, SPAIN. ; and M. VILLA, Departamento de Quimica, Universidad Autonoma Metropolitana - I., 09340, D. F., MEXICO.. In the present communication the vibrational zero point corrections for the methyl torsion and amine hydrogen wagging potential energy function are determined, and the corresonding spectrum calculated. It is found that the amine inversion barrier increases from 1727 cm 1 up to 1850.65 cm 1 in better agreement with respect to the value of 1937 cm 1 deduced from experiment. In addition, the spitting values obtained for the fundamental band agree fairly well with the experimental data reported in the literature. TI05 CURVILINEAR INTERNAL VALENCE COORDINATE HAMILTONIAN FOR AMMONIA

15 min

2:38

JANNE PESONEN, ANDREA MIANI, Laboratory of Physical Chemistry, P.O. Box 55 (A. I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland; LAURI HALONEN, JILA, University of Colorado, Campus Box 440, Boulder, Colorado 80309. A new six-dimensional vibrational Hamiltonian based on curvilinear internal valence coordinates is presented for ammonia. The square of the inversion coordinate adopted is similar to the often used out-of-plane bending coordinate for planar XY3 -type molecules. Conventional symmetrized internal coordinates are employed for the other vibrational degrees of freedom. The exact kinetic energy operator is given in closed form. TI06 15 min 2:55 THEORETICAL STUDY OF THE METHANE STRETCHING VIBRATIONAL ENERGY LEVEL STRUCTURE CLOSE TO A NICKEL SURFACE LAURI HALONEN AND DAVID NESBITT, JILA, University of Colorado, Campus Box 440, Boulder, Colorado 80309. A vibrational Hamiltonian has been constracted for methane to study stretching vibrational energy level structure when the molecule approaches a nickel surface. A local mode Hamiltonian is used for an isolated molecule. A LEPS potential energy function is chosen to describe surface-molecule interactions. Stretching vibrational energy levels have been calculated variationally at different molecular distances and orientations from the surface. In the case of the local mode pairs of states (1000A1 /F2 ) and (2000A1 /F2 ), the symmetric A1 states decrease in energy and the antisymmetric F2 states stay almost constant in energy and become stretching states of CH3 as the methane molecule approaches the surface. This indicates that the excitation of the symmetric states would have an effect on the chemical reactivity close to the surface but the excitation of the antisymmetric states would not.

149

TI07 ANTIGRAVITATION QUANTUM HIGH ENERGY KHOLMURAD KHASANOV, [email protected].

Samarkand State University,

15 min

Uzbekistan,

703004,

email:

3:12

han-

An electric discharge in rarefied argon and nitrogen gas produces a quantum antigravity of high energy which was registered by taking an negative picture in total darkness. When such radiation is taking place, gravitons from the gases flee straight away from the earth causing the weight of the substance, in this case quartz (SiO2 ), to decrease by 1/100 of its’ original weiaght. The substance quickly returns to its’ original weight after the electric discharge has been removed. This experiment has been performed on many types of material, all with similar results. This phenomena takes place as a result of the quantum electro-magnetic field bending space, thus changing the gravitational weight of the material a a Kholmurad Khasanov, The Phenomemon of Electro-Gravitation, Abstracts of the Symposium on Experimental Gravitation, Samarkand, Auguat 16-21, 1999

Intermission

TI08 15 min 3:45 DIRECT TWO QUANTUM JUMPS IN HIGH FREQUENCY ELECTRON PARAMAGNETIC RESONANCE DESCRIBED BY A 3-LEVEL DENSITY MATRIX FORMALISM. W. LEO MEERTS, Department of Molecular and Laser Physics, University of Nijmegen, P.O. Box 9010, 6500 GL Nijmegen, The Netherlands; PAUL J.M. van KAN, Department of Molecular Spectroscopy, University of Nijmegen; ETIENNE GOOVAERTS, Department of Physics, University of Antwerp, UIA campus, 2610 Wilrijk, Belgium. High frequency EPR spectroscopy is a powerful tool for revealing the magnetic resonance properties of Nickel(II) complexes with an S=1 (triplet) ground state. For Ni(ethylenediamine)3 (NO3 )2 we observed first-order spectra at 95 GHz. A MS = 1 and the MS = 1 MS = 0 transitions single crystal of this compound shows two normal MS = 0 with an effective zero-field splitting depending on the orientation in the magnetic field. Moreover, a direct transition that MS = 1 is observed. For this transition, the intensity is strongly orientation dependent. corresponds to MS = 1 At the magic angle all three transitions fall on top of each other for this axially symmmetric crystal. All three transitions show the same dependence on microwave power. The existence of a two quantum jump (
MS = 2 transition) and its dependence of the microwave power cannot be understood and explained in a (conventionally used) 2-level picture of each transition in a triplet system. In the current work we present the results of a 3-level density matrix calculation. The calculation starts from the general equation of motion of the density matrix operator in the Heisenberg picturea . The resulting set of differental equations is solved numerically. The solutions reproduce very well the observed linewidths and intensities. The two quantum jump follows intrinsically form the model. a N.

Dam, Ethylene Hot-band Spectroscopy and Relaxation phenomena, Thesis 1988, University of Nijmegen.

150

TI09 15 min 4:02 DIFFUSION QUANTUM MONTE CARLO ON MULTIPLE POTENTIAL SURFACES: A SCALABLE APPROACH FOR CALCULATING SHIFTS IN TRANSITION FREQUENCIES IN CLUSTERS ANNE B. McCOY, Department of Chemistry, The Ohio State University, Columbus, OH, 43210. An approach is described for applying Diffusion Monte Carlo (DMC) techniques to problems that involve two or more coupled potential energy surfaces. This technique combines surface hopping with traditional Diffusion Monte Carlo approaches. The accuracy and efficiency of this approach will be demonstrated through studies of the shifts in the frequencies of the fundamental and first overtone of the HF stretch in linear chains of HF. In the case of (HF )2 the errors in the energies, calculated using DMC, are smaller than the statistical uncertainty of DMC. In this case, the vibrational excitation is localized in one of the monomers, but, as the number of HF monomers is increased to ten, the excitation becomes delocalized. Extensions of this approach to realistic studies of the IR spectrum of molecular clusters will be discussed.

TI10 NONEXPONENTIAL DEPHASING IN QUANTUM MECHANICAL SYSTEMS

15 min

4:19

V. WONG and M. GRUEBELE, Department of Chemistry and Beckman Institute for Advanced Science and Technology, University of Illinois,Urbana IL 61801. Power law dephasing of quantum systems at intermediate times is investigated. The Hamiltonians of systems whose survival probabilities exhibit ideal power law behavior are found to contain strong correlations when cast into a ’golden rule’ representation. Quantum dynamics simulations of molecules generated from a local random matrix model have produced survival probabilities with power law decays. Correlations of the type observed for the case of ideal power laws are also seen for these molecules. Decoherence of spin boson systems are also found to display power law behavior.

TI11 15 min 4:36 ANGULAR MOMENTUM TRANSFER IN ROTATIONAL ENERGY TRANSFER: TESTS OF GENERALIZED SCALING LAWS APPLIED TO O2 STEPHEN L. COY, K. RYBAK, J. I. STEINFELD, MIT Department of Chemistry, Cambridge, MA 02139. In inverting experimental data to relaxation matrix elements and to basis rates with predictive power, only Boyd, Ho and Rabitz a have tried to avoid restrictive and arbitrary limitations to angular momentum scaling models. The commonly applied scaling models (such as ECS-EP) enforce a few-parameter smooth basis rate variation which is quite different from calculated results, especially at low values of angular momentum transfer. The Rabitz approach has met with very limited success, but the more restricted forms do not extract all the information available in current data sets. We have used the extensive linewidth dataset available for A¡-X O2 transitions to develop and test a new method of determining angular momentum transfer basis rates via global optimization with non-negative constraints. This makes use of the experimental results that we have recently reported. b We will describe these results, relate them to other scaling schemes, and show how these differences can be experimentally tested. a Boyd b Yang

R, Ho TS, Rabitz H, J Chem Phys 108,1780(1998) SF, Canagaratna M, Witonsky S, Coy SL, Steinfeld JI, and Kachanov A, submitted to J. Molec. Spectrosc.

151

TI12

15 min

~ 2 ; vXH BOUND ROVIBRATIONAL ENERGY LEVELS FOR THE NeXH/D (X COMPLEXES

4:53

= 0; X = O; S ) VAN DER WAALS

HEE-SEUNG LEE and ANNE B. McCOY, Department of Chemistry, The Ohio State University, Columbus, OH 43210.

~ 2 ) Bound rovibrational energy levels for the complexes of a neon atom with OH or SH in their ground electronic state (X are obtained by a variational calculation with J = 3=2; 1=2 using the potential energy surfaces recently developed by Cybulski and coworker.a In these calculations, a descrete variable representation (DVR) is employed for the intermolecular stretching coordinate and symmetrized Hund case (a) basis functions are used for the rotational motion of XH fragment. For both species, the ground states have linear geometries with the hydrogen atom pointing toward the rare gas atom. In the case of the SH complex, the motion of SH is found to be close to the free rotor limit, but the couplings induced by the potential and Coriolis terms in the Hamiltonian make the OH complex deviate significantly from the free rotor limit. A comparion with available experimental data is also made. a S.

M. Cybulski (to be published)

TI13 15 min FINGERPRINTS OF SADDLE-NODE BIFURCATION IN SPECTRUM AND DISSOCIATION OF HOCl

5:10

S. GREBENSHCHIKOV, J. WEISS, J. HAUSCHILDT, and R. SCHINKE, MPI f¨ur Str¨omungsforschung Bunsenstraße 10, D-37073 G¨ottingen, Germany. We present a detailed analysis of the bound-state spectrum of HOCl (hypoclorous acid) in the ground electronic state. Exact quantum mechanical calculations (filter diagonalization) are performed employing an ab initio potential energy surface. The wave functions of all bound states up to the HO+Cl dissociation threshold are visually inspected in order to assign the spectrum in a rigorous way and to elucidate how the spectrum develops with energy. The dominant features are (1) a 2:1 anharmonic resonance between the bending mode and the OCl stretching mode, which is gradually tuned in as the energy increases, and (2) a saddle-node bifurcation, i.e., the sudden birth of a new family of states, caused by the resonance. We carefuly investigate the bifurcation in terms of the structure of the classical phase space (periodic orbits, continuation/bifurcation diagram). To this end, a two-dimensional adiabatic model is developed, which quantitatively reproduces the exact three-dimensional results. The classical phase space of this dynamical model can be completely mapped using the Poincare surfaces of section. It is shown that the saddle-node bifurcation is associated with splitting of the phase space into a set of zones divided by separatrices. Close correspondence is established between the finest details of the quantum wave functions and the topology of periodic orbits (stable and unstable). Of special interest are the quantum states localized on the classical separatrix. It is also discussed how the spectrum of bound states persists into the continuum and how the various types of quantum mechanical continuum wave functions affect the state-specific dissociation rates.

152

WA. PLENARY WEDNESDAY, JUNE 14, 2000 – 8:45 AM Room: AUDITORIUM INDEPENDENCE HALL Chair: BRUCE BURSTEN, The Ohio State University, Columbus, OH

WA01 40 min 8:45 JET COOLED LASER SPECTROSCOPY OF HYDROCARBON RADICALS AND MOLECULAR IONS IN SLIT SUPERSONIC EXPANSIONS DAVID J.NESBITT, SCOTT DAVIS, MICHAL FARNIK, DAIRENE UY, MARJO HALONEN, AND PINGRONG YU, JILA, National Institute for Standards and Technology, Department of Chemistry and Biochemistry, University of Colorado, Boulder, CO, 80309. The novel combination of pulsed slit supersonic expansions and pulsed electrical discharges results in a remarkably intense source of jet cooled chemical reactive species in a long path length geometry ideal for near shot noise limited direct absorption spectroscopy with high resolution tunable lasers. This proves particulary powerful in the near infrared, where the reduced Doppler linewidths in the slit jet permits rovibrational, open shell fine structure and sometimes even hyperfine structure to be resolved. Most importantly, this method provides access to spectra of transient species at very low temperatures (10K), which greatly simplifies the resulting spectroscopic assignment and analysis. This talk will develop the background methodology of these slit discharge methods, and then discuss three sample hydrocarbon radical systems studied: from 1) the relatively simple methyl (CH3 ) radical, which by virtue of sub-Doppler linewidths permits both Fermi contact information on gas phase spin densities to be extracted for the first time and elucidates the effects of spin polarization through CH molecular bonds, 2) the more complicated ethyl (CH3 CH2 ) radical, which exhibits strongly coupled large amplitude motion between wagging of the CH2 radical center and internal rotation around the C-C bond, to 3) the allyl (CH2 CHCH2 )radical, which represents the fundamental paradigm for electron delocalization in a  system. Time permitting, recent extensions to high frequency discharge modulation techniques and applications to jet cooled molecular ion spectroscopy will also be discussed.

WA02 40 min 9:30 HIGH-RESOLUTION ELECTRON AND PHOTOELECTRON SPECTROSCOPY IN THE EXTREME ULTRAVIOLET (XUV) F. MERKT, Laboratorium f¨ur Physikalische Chemie, Eidgen¨ossische Technische Hochschule, ETH-Zentrum, CH-8092 Z¨urich, Switzerland. We present recent progress in high-resolution spectroscopic studies of atomic and molecular Rydberg states using narrowbandwidth XUV laser sources and millimeter waves. From such studies one can (1) derive very detailed information on the energy level structure (including the hyperfine structure) of molecular Rydberg states up to principal quantum numbers beyond n = 50, (2) improve the current understanding of the unusual properties of the very high Rydberg states with n > 150 probed by pulsed-field-ionization zero-kinetic-energy (PFI-ZEKE) photoelectron spectroscopy, and (3) use this improved understanding to better exploit the advantages of this technique, in particular its resolution, to study the structure and dynamics of molecular ions. To illustrate the potential of high-resolution electron and photoelectron spectroscopic studies, we shall present our recent results on several molecular systems such as H2 , N2 , CH4 and the corresponding singly charged cations.

Intermission

153

WA03 40 min 10:30 MOLECULAR BEAM SPECTROSCOPIC STUDIES OF TRANSITION METAL CONTAINING RADICALS TIMOTHY C. STEIMLE, Department of Chemistry and Biochemistry, Arizona State University, Tempe, Az, 85287-1604. This oration will focus on four subjects: a) the experimental approaches utilized in the studies of molecular beam samples of metal containing radicals, b) the comparison of the permanent electric dipole moments, , of early transition metal diatomic molecules, c) optical spectroscopy of transition metal dicarbides, and d) new directions using absorption based spectroscopy. The experimental database of  values for early 3d and 4d transition metal sulfides, oxides and nitrides is now extensive enough to examine ligand-induced trends in the ionic nature of bonding1 . The validity of a simple, single configuration molecular orbital correlation diagram will be described. The third topic is a report on the analysis of the high resolution optical spectrum of YCC, being performed in collaboration with Prof. A.J. Merer(U.B.C.), and the preliminary analysis of a low resolution optical study of what we beleive to be PtCC. Yttrium dicarbide is the only gas-phase metal dicarbide to be detected via an optical spectroscopic technique2 . The correlation of the determined physical properties to their proposed role as catalytic agents in the formation of single walled nanotubes3 will also be presented. Absorption based transient frequency modualtion (FM) spectroscopy4;5 will be proposed as a new direction for the study of metal containing molecules in light of our recent comparison of this technique with LIF for TiS and PtC6 .

1. 2. 3. 4. 5. 6.

R. Bousquet, K.C. Namiki and T.C. Steimle (accepted J. Chem Phys). T.C. Steimle, A.J. Marr, J. Xin, A.J. Merer, K. Anthanassenas and D. Gillett, J. Chem. Phys. 106, 2060 (1997). A.A. Puretzyk, D.B. Geoheagan, X. Fan, S.J. Pennycook, Appl. Phys. Lett. 76, 182 (1997). J.C. Bloch, R.W. Field, G.E. Hall and T.J. Sears, J. Chem. Phys. 101, 1717 (1994). M.C. McCarthy, J.C. Bloch and R.W. Field, J. Chem. Phys. 100, 633 (1994). T.C. Steimle, M.L. Costen, G.H. Hall, and T.J. Sears, Chem. Phys. Lett. accepted (2000).

154

WA04 40 min 11:15 SUBMILLIMETER AND MID/FAR-INFRARED SPECTROSCOPY IN INTERSTELLAR AND CIRCUMSTELLAR CLOUDS JOSE CERNICHARO, CSIC. IEM. Dpt. Molecular Physics. C/Serrano 121. 28006 Madrid. Spain. email:[email protected]. The observation of the rotational emission of molecules in the space can be used to determine the physical and chemical conditions of the emitting gas. The low–J pure rotational transitions of species like CO, HCN, CN, HCO+ , : : :, have been observed during the last thirty years using ground-based radio telescopes operating at millimeter and submillimeter wavelengths. Many molecules have been discovered in this way in the space, even prior to its detection in the terrestrial laboratories. The gas that can be investigated through these molecular transitions is cold and of moderate volume density. Although many important studies have been carried out on galactic and extragalactic molecular clouds, these observations can not give an accurate view of the warm and dense regions where star are formed and of the hot gas surrounding stars in the last stages of their evolution. The ISO satellite has offered us the opportunity to study the mid and far-infrared spectrum of molecular clouds and evolved stars. In this lecture I will review the main results obtained in the field of molecular astrophysics with ISO. The physical processes related to star formation can be, for the first time, analyzed in great detail through the observation of high excitation lines of water vapor and other molecular species. Although most of the observed molecules, H2 O, CH+ , high–J rotational lines of CO and HCN, have well known rotational constants, the analysis of the observed emission has shown the lack of some important molecular properties that have to be obtained from laboratory experiments or from ab initio quantum chemistry calculations. In this lecture I will review the type of molecules that can be observed in the space in the far– and mid–infrared and the physical processes related to the pumping of the ro-vibrational levels of the most abundant species (C2 H2 and HCN in C-rich objects, H2 O in O-rich objects). The future space platform “Far Infrared Space Telescope” (FIRST) will be equipped with high resolution heterodyne receivers that will allow to study the chemical complexity of the universe. In order to prepare the scientific program of this mission, a close collaboration between astronomers and molecular spectroscopists is needed. The spectroscopic information that we need to get the maximum scientific output from FIRST will be reviewed.

155

WE. MICROWAVE WEDNESDAY, JUNE 14, 2000 – 1:30 PM Room: 1153 SMITH LAB Chair: KEN LEOPOLD, University of Minnesota, Minneapolis, MN

WE01 MILLIMETER WAVE SPECTRA OF THE H2 -H2 O VAN DER WAALS COMPLEX

15 min

1:30

CHRISTOPHER WHITHAM, KENSUKE HARADA and KEIICHI TANAKA, Institute for Molecular Science, Myodaiji, Okazaki 444-8585 Japan. Twelve pure rotational transitions of the highly non-rigid H2 -H2 O Van der Waals complex have been observed using a free jet expansion millimeter wave absorption spectrometer in the 70-210 GHz region. Following the recent infrared work of Weida and Nesbitt a all the transitions are believed to originate from the ortho-H2 j=1, hydrogen internal rotation state. The water internal rotor states involved are the para-H2 O 000 , and the ortho-H2 O 101 , f and e states. In addition, four rotational transitions of the H2 -D2 O complex have also been observed. Work is continuing in recording and analysing the spectra which will provide information on the potential energy surface for the complex and the interesting question of whether the water acts as a proton acceptor or donor, something which may depend on the hydrogen internal rotor state. a M.

J Weida and D. J Nesbitt, J. Chem. Phys. 101, 5824 (1999).

WE02 FT MICROWAVE SPECTROSCOPY OF THE H2 O-O2 COMPLEX

10 min

1:47

YASUKO KASAI, Millimeter-Wave Remote Sensing Section, Global Environment Division Communication Research laboratory, Tokyo 184-8795, Japan; YOSHIHIRO SUMIYOSHI, and YASUKI ENDO, Depertment of Pure and Applied Sciences, College of Art and Sciences, The University of Tokyo, Tokyo 153-8902, Japan. Rotational transitions of a van der Waals complex, H2 O-O2 , in the 3 B2 ground vibronic state have been observed using a pulsed nozzle Fourier-transform microwave spectrometer for the first time. Six transitions observed in the frequency region between 8 - 30 GHz have been assigned to the rotational and fine structure components of the H2 O-O2 complex, and are analyzed to obtained the rotational, centrifugal distortion, and spin-spin coupling constants. Each of the observed transitions is further split into several hyperfine components due to the water protons. Analysis of the hyperfine structure is in progress. The structure of the complex is considered to be C2v .

156

WE03 15 min 1:59 MICROWAVE SPECTRUM AND STRUCTURE OF THE OPEN-SHELL VAN DER WAALS COMPLEX Ar–ClO2 ¨ MARTIN SCHAFER, Laboratorium f¨ur Physikalische Chemie, ETH Zentrum, CH-8092 Z¨urich, Switzerlanda . Due to its very high resolution, microwave spectroscopy is a very sensitive method, not only for the investigation of molecular geometries, but also for the elucidation of information about the electronic structure through the analysis of the hyperfine structure. In an open-shell Van der Waals complex, it is possible to study an possible perturbation of the electronic structure of the radical upon complexation, or the unpaired electron delocalisation within the complex. But because of the complexity of their rotational spectra, only very few open-shell Van der Waals complexes have been studied by microwave spectroscopy. The microwave spectra of the open-shell complexes Ar–35 ClO2 and Ar–37 ClO2 have been measured using a pulsed-jet Fourier transform cavity microwave spectrometer in the frequency range 5–24 GHz. These complexes have been formed in a supersonic expansion of ClO2 entrained in argon. The analysis of Zeeman patterns and extensive microwave-microwave double resonance experiments were used to assign individual hyperfine components of rotational transitions. A tunnelling motion between two equivalent positions of the argon atom on opposite sides of the ClO2 molecule cause splittings of the rotational levels, but due to the presence of two identical zero spin nuclei, only rotational states with odd Ka values occur in the lower tunnelling state and only states with even Ka values occur in the higher tunnelling state. Structure data have been obtained from the analysis of the spin-interaction parameters and of the moments of inertia of both isotopomers. The observed tunnelling splitting is much smaller than that for similar complexes as Ar–SO2 , Ar–O3 or Ar–NO2 . a Present

address: Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260.

WE04 VIBRATION-ROTATIONAL-TUNNELING (10 ,n=0) (00 , n=0) TRANSITION IN Ar
ND3

15 min

2:16

SANDHYA GOPALAKRISHNAN, DMITRY G. MELNIK, TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210; and FRANK C. DE LUCIA, The Ohio State University, Dept. of Physics, Microwave Laboratory, 174 W. 18th Avenue, Columbus OH 43210. A vibration-tunneling-rotation transition in the Ar
ND3 complex has been observed using the previously reporteda Pulsed Jet Fast Scan Submillimeterwave Spectrometer . The spectrum was assigned as rotational lines belonging to (10 ,n=0) (00 , n=0) vibrational transition, corresponding to activation of hindered rotation of the monomer in the complex with zero quanta of van der Waals’ stretch in each state. An analysis of the rotational and quadrupole structure is presented. The implications of the new measurements for the potential energy surface of the complex will be discussed. a D.Melnik,

S.Gopalakrishnan, T.A.Miller, and F.C.De Lucia, 54th International Symposium on Molecular Spectroscopy, June 99

WE05 ROTATIONAL SPECTROSCOPY OF OCS–N2 O

15 min

2:33

OLAYINKA A. OYEYEMI, HELEN O. LEUNG, Department of Chemistry, Mount Holyoke College, South Hadley, MA 01075. The rotational spectrum of OCS–N2 O has been recorded in the 7 - 18 GHz region using a pulsed molecular beam, Fourier transform microwave spectrometer. Both a- and b-type transitions are observed, and the hyperfine structure due to the two quadupolar 14 N nuclei have been analyzed using the Watson A-reduced Hamiltonian with the inclusion of hyperfine interactions. The spectroscopic constants are consistent with a planar structure with the centers of mass of the two subunits ˚ The OCS subunit is approximately perpendicular to the intermolecular axis while the N2 O subunit separated by 3.52 A. forms an angle of about 56Æ with the intermolecular axis.

157

WE06 15 min 2:50 VAN DER WAALS BENDING BAND OF THE ArDCN CLUSTER OBSERVED BY MILLIMETER-WAVE SPECTROSCOPY COMBINED WITH A PULSED SUPERSONIC-JET TECHNIQUE KEIICHI TANAKA, S. BAILLEUX, A. MIZOGUCHI, and K. HARADA, Institute for Molecular Science, Okazaki, 444-8585, Japan. Millimeter-wave absorption spectroscopy combined with a pulsed-jet expansion technique was applied to the measurement of the rovibrational transitions of the van der Waals (vdW) bending bands of the ArDCN cluster in the frequency region of 182-294 GHz. Sixteen and thirty-seven rovibrational lines were observed for the 1 - 0 and 1 - 0 bands, respectively, split into hyperfine structure due to the nitrogen nucleus. A set of accurate molecular constants, including the band origins, rotational constants, nuclear coupling constants, and the Coriolis interaction constant between the 1 and 1 bending substates, was determined. The band origins for the 1 - 0 and 1 - 0 bands of ArDCN, 189.017380(7) GHz and 195.550736(12) GHz, are larger by 24.126585(9) and 13.566314(16) GHz than the corresponding values of ArHCN, respectively. The abnormal isotopic effect on the vibrational frequencies is attributed to the characteristic potential energy surface of ArH(D)CN, which has two minima, corresponding to the linear configuration and a much shallower minimum at the T-shaped configuration. The rotational and quadrupole coupling constants for the excited state are quite different from those of the ground state. For example, the rotational constants 1926.8863(16) and 1967.8768(9) MHz for the excited the 1 and 1 states are significantly larger than that of the ground 0 state, 1574.79316(24) MHz. It indicates the shrinkage of the bond length of the cluster by about 0.402 - 0.440 A on the excitation of the vdW bending mode, together with the change from the linear form in the ground (j = 0) state to the T-shaped form in the first excited (j = 1) state. The determined molecular constants were compared with those calculated with the potential energy surface calculated at CCSD(T) level.

WE07 15 min 3:07 MILLIMETER-WAVE SPECTROSCOPY FOR VAN DER WAALS BENDING HOT BANDS OF THE Ar-HCN COMPLEX A. MIZOGUCHI, S. BAILLEUX, K. HARADA, and K. TANAKA, Department of Applied Molecular Science, Institute for Molecular Science, Okazaki 444-8585, Japan. We report a millimeter-wave spectroscopic study for the vdW bending j =2-1 hot bands of the Ar-HCN complex. In the frequency region of 150 - 300 GHz, in total 154 rovibrational lines including hyperfine splittings for all j =2-1 subbands have been observed by using direct absorption spectroscopy combined with a pulsed nozzle. The spectroscopic constants including the Coriolis interaction constants were determined precisely. The energies of the jK j sublevels in the j =2 state decrease with increasing jK j. The order is reversed against that in the j =1 statea . The change in distance between Ar and center of mass of HCN for the  and  states due to the excitation of the bending vibration from j =1 to 2 is not obvious as in the case of that from j =0 to 1. The eQq aa constants in the 2 , 2 and
2 states are determined to be -0.4, -0.6 and 1.2 MHz [-1.3, -0.7 and 1.3 MHz in the free rotor limit respectively], suggesting the 2 and
2 states have more free rotor character. a S.

Drucker, A. L. Cooksy and W. Klemperer, J. Chem. Phys., 98, 5158(1993).

Intermission

158

WE08 15 min 3:40 EVIDENCE FOR NOBLE GAS-METAL CHEMICAL BONDING: FT-MICROWAVE SPECTRA, GEOMETRIES AND HYPERFINE CONSTANTS OF THE COMPLEXES Ar-CuX (X=F, Cl, Br). COREY J. EVANS and MICHAEL C. L. GERRY, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B. C., Canada, V6T 1Z1. The rotational spectra of the complexes Ar-CuF, Ar-CuCl and Ar-CuBr have been measured between 5-22 GHz using a cavity pulsed jet Fourier transform microwave spectrometer. They were prepared by ablating Cu metal with a Nd:YAG laser (532 nm) and allowing the vapour to react with a suitable precursor contained as SiCO > SiSiO. The computation of  resulted in negative values for all of these radicals due to the energy ordering of the split potential energy surfaces. The  predicted for A~ 3  CCO (-0.153 at TZ3P(2f) EOM-CCSD) is good agreement with the  value of -0.172 from Devillers and Ramsay’sa experimental analysis. ——————– a Devillers, M. C. and Ramsay, D. A., Can. J. Phys., 1971, 49, 2839.

175

WH05 15 min 2:56 FOURIER TRANSFORM SPECTRA OF COPPER DICHLORIDE : RENNER-TELLER EFFECT IN ROVIBRONIC LEVELS OF THE GROUND STATE P. CROZET, E. BOSCH, A. J. ROSS, Laboratoire de Spectrom´etrie Ionique et Mol´eculaire (UMR 5579 CNRS), Bˆatiment 205, Universit´e Lyon I, Campus la Doua, 69622 Villeurbanne Cedex, France; and J. M. BROWN, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, England. High-resolution Fourier transform spectra of the laser-induced fluorescence of 63 Cu37 Cl2 produced in a cell have been recorded following excitation of a single vibronic level of the E 2 u electronic state. Fluorescence occurs in combination bands to a broad spread of rovibrational levels in the ground electronic state, X 2 g(3=2) . A global rovibronic model is proposed for the ground state based on an effective Hamiltonian, which fits experimental data (2782 fluorescence lines, lower state quantum numbers : v1 = 0 6; v2 = 0 2; v3 = 0 4, and J = 4 12 80 12 ) with a root mean square error of 0.019 cm 1 . Vibrational, rotational and Renner-Teller parameters are obtained (e.g. !2 = 95.195 cm 1 , Be = 0.055106(3) cm 1 ,  = - 0.1893). A revised value for the equilibrium internuclear distance Cu-Cl is deduced: re (Cu-Cl) = 0.20341(3) nm.

Intermission

WH06 Invited Talk 30 min 3:30 MULTI-MODE DYNAMICAL JAHN-TELLER EFFECTS IN MOLECULAR ELECTRONIC SPECTRA AND INTERNAL CONVERSION DYNAMICS ¨ HORST KOPPEL, Theoretical Chemistry, University of Heidelberg, INF 229, D-69120 Heidelberg, Germany. An overview is given over the basic theory of the Jahn-Teller (JT) effect in molecular electronic spectra, with an emphasis on doubly degenerate electronic states. While in the weak-coupling limit the nuclear motion is generally nonadiabatic, i.e. proceeds on both JT-split potential energy surfaces simultaneously, for strong coupling adiabatic and nonadiabatic energy regimes can be distinguished. Then, also the phenomenon of the geometric phase becomes of relevance. When another (degenerate or nondegenerate) electronic state is not too far in energy it may also interact with the degenerate electronic state in question (pseudo-JT coupling). In fact, this interaction can be important for an energetic separation as large as 2-3 eV. Pertinent examples of JT systems treated by us theoretically in the past several years, partly in collaboration with other groups, include electronic spectra of triatomic hydrogena , the methoxy radicalb and the benzene radical cationc . The salient features of the various interaction mechanisms in these cases are elucidated based on ab initio calculated JT coupling parameters. - Additional strong pseudo-JT coupling effects are identified in the radical cations of the tetraphosphorous moleculed , of allenee and again benzenef . Their profound impact on the internal conversion dynamics is established by wave-packet dynamical simulations. a S.

Mahapatra and H. K¨oppel, J. Chem. Phys. 109, 1721 (1998); Phys. Rev. Lett. 81, 3116 (1998). H¨oper, P. Botschwina and H. K¨oppel, J. Chem. Phys. 112, 4132 (2000). c J. Eiding, R. Schneider, W. Domcke, H. K¨ oppel and W. von Niessen, Chem. Phys. Lett. 177, 345 (1991). d R. Meiswinkel and H. K¨ oppel, Chem. Phys. Lett. 201, 449 (1993). e S. Mahapatra, L.S. Cederbaum and H. K¨ oppel, J. Chem. Phys. 111, 10452 (1999). f M. D¨ oscher and H. K¨oppel, Chem. Phys. 225, 93 (1997). b U.

176

WH07

15 min

4:05 RENNER-TELLER COUPLING IN OPEN-SHELL COMPLEXES: THE ROVIBRONIC STRUCTURE OF CH(A2
)Ne GALINA KERENSKAYA, ALEXEY L. KALEDIN, and MICHAEL C. HEAVEN, Department of Chemistry, Emory University, Atlanta, GA 30322. Open-shell complexes that involve radicals in orbitally degenerate states exhibit weak-field Renner-Teller coupling effects. The CH(A2
)-Ne complex is an interesting example as both the anisotropy of the intermolecular potential energy surface and the spin-orbit coupling constant are small. The level splittings produced by the interaction with Ne produce a dense manifold of states. Consequently, the congested fluorescence excitation spectra observed for the A-X bands of CH-Ne could not be analyzed. The spectra have been simplified using fluorescence depletion techniques. Hole-burning of the B-X fluorescence via the A-X bands provides well-resolved spectra for the latter. Even so, unambiguous assignment of the lines still could not be achieved using a conventional combination difference analysis. To resolve the ambiguities we are predicting the ro-vibronic structure of CH(A)-Ne using high-level ab initio methods. Potential energy surfaces have been calculated using the CASSCF-MRCI(SD) level of theorya . The bound states supported by these surfaces are calculated using product basis sets for the angular coordinates, combined with an optimized DVR treatment of the radial coordinate. The results of these calculations and assignments for the A-X bands of CH-Ne will be presented. Work supported by the National Science Foundation a U.

Schnupf, Ph. D. Thesis, Dept. of Chemistry, Emory University 1995.

WH08 10 min 4:22 LARGE-SCALE COUPLED CLUSTER CALCULATIONS FOR THE TWO RENNER-TELLER COMPONENTS OF HCCO P. BOTSCHWINA, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany.

177

WH09

15 min 4:34 2 THE RENNER-TELLER EFFECT FOR THE  ELECTRONIC EXCITED STATE OF MgCN; AN AB INITIO MOLECULAR ORBITAL PREDICTION ERIKA ODAKA, TETSUYA TAKETSUGU, TSUNEO HIRANO, Department of Chemistry, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan; UMPEI NAGASHIMA, National Institute for Advanced Interdisciplinary Research, Ibaraki 305-8562, Japan. MgNC is the first Mg-bearing molecule in space identified by us through the cooperative studies between ab initio molecular orbital calculationsa and the laboratory microwave studyb . MgCN is its isomer, and has also been identified in space by Ziurys et al.c We have generated the potential energy surface of 2  electronic excited states of MgCN at the MRSDCI/aug-cc-pVQZ level of calculations, and predicted spectroscopic constants. The potential energy surface shows that MgCN has a linear structure in the 2  electronic state, which splits into two states, 2 A0 and 2 A" via Mg-C-N bending motions (Renner-Teller splitting). The Renner parameter  is calculated as 0.24 for 2  in MgCN, which is smaller than the corresponding value for 2  in MgNC ( = 0.32). a K.

Ishii, T. Hirano, U. Nagashima, B. Weis, and K. Yamashita, Astrophys. J. 410, L43, (1993) Kawaguchi, E. Kagi, T. Hirano, S. Takano, and S. Saito, Astrophys. J. 406, L39, (1993) c L. M. Ziurys, A. J. Apponi, M. Guelin, and J. Cernicharo Astrophys. J. 445, L47, (1995)

b K.

178

WI. MATRIX WEDNESDAY, JUNE 14, 2000 – 1:30 PM Room: 1005 SMITH LAB Chair: TAKAMASA MOMOSE, Kyoto University, Kyoto, Japan

WI01 SPECTROSCOPY OF CHLORINE MONOFLUORIDE ISOLATED IN RARE GAS MATRICES

15 min

1:30

M. BARGHEER, P. DIETRICH and N. SCHWENTNER, Institut f¨ur Experimentalphysik, Freie Universita¨ t Berlin, Arnimallee 14, 14195 Berlin, Germany. We report for the first time spectroscopy of chlorine monofluoride (ClF) isolated in rare gas matrices. The strongest absorption is to the dissociative 1 u state around 275 nm. Upon laser excitation at 308 nm into this state we observe in emission a vibrational progression from 580 to 930 nm which can be safely attributed to A0 ! X with !e = 780:7 cm 1 and !e xe = 6:5 cm 1 . The population accumulates in the A0 state with a phosphorescence lifetime of the order of one second. Excitation from A0 to the ionic manifold results in two broad emission bands at 425 and 510 nm respectively. ClF is an interesting molecule in the perspective of condensed phase photochemistry. Upon excitation at 308 nm it dissociates with a quantum yield similar to the F2 molecule. But as a heteronuclear molecule the two fragment atoms behave extremely differently: From experiments on matrix isolated Cl2 in Kr and Ar it is known that cage exit of Cl atoms is negligible. In contrast, the fluorine atom leaves the cage with up to unit probability with increasing excess energy. The fragmented fluorine atoms and the parent molecules are recorded spectroscopically and the dissociation and recombination kinetics are analysed. The blue fluorescence bands after two-photon excitation are established as a channel for femtosecond pump-probe spectroscopy and time-resolved measurements of the dissociation in a condensed-phase environment are discussed.

WI02 15 min FTIR ISOTOPIC STUDY OF C-C STRETCHING MODES OF THE C12 CHAIN TRAPPED IN SOLID Ar

1:47

X.D. DING, S.L. WANG, C.M.L. RITTBY, and W.R.M. GRAHAM, Department of Physics and Astronomy, TCU, Fort Worth, TX 76129. The increasing length of carbon chains, which are being investigated, makes detailed isotopic studies to test vibrational assignments progressively more difficult. The large number of overlapping isotopomer bands resulting from 13 C enrichment can make unambiguous assignments problematical. We report here the results of an investigation of the linear C12 produced by laser ablation of graphite and trapped in solid Ar. The Fourier transform infrared spectrum is simplified by limiting the isotopomers produced to those with single 13 C substitutions. Comparison of measured frequencies and isotopic shifts with the results of density functional theory calculations at the B3LYP/cc-pVDZ level has resulted in the identification of the 8 = 1997.2 cm 1 and 9 = 1818.0 cm 1 stretching modes, with very good agreement between experiment and theory. Since bands close to these frequencies had previously been reported in Ne matrices and assigned to the anion, the Ar measurements have also been compared to DFT predictions and simulated spectra for C12 .

179

WI03

15 min

2:04

THE INFRARED SPECTRUM OF H2 O2 + TRAPPED IN SOLID NEON CATHERINE L. LUGEZ, WARREN E. THOMPSON, and MARILYN E. JACOX, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441. When a Ne:H2 O2 + sample is codeposited at approximately 5 K with a beam of microwave-excited neon atoms, photoionization and Penning ionization of the H2 O2 leads to the stabilization of the H2 O2 + cation. Although the energy of the excited neon atoms exceeds that required for the formation of HO2 + from H2 O2 , as has been previously found in photoionization studies, the yield of this fragment ion is small. The infrared spectra observed for H2 O2 + and for its deuterium-substituted isotopomers will be compared with those predicted by ab initio calculations.

WI04 15 min 2:21 INFRARED SPECTRA OF THE PRODUCTS OF THE PHOTODISSOCIATION AND PHOTOIONIZATION OF NCCN, ClCN, AND BrCN AT 16.6-16.85 eV WARREN E. THOMPSON and MARILYN E. JACOX, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899-8441. When a Ne:C2 N2 , Ne:ClCN, or Ne:BrCN sample is codeposited at approximately 5 K with neon atoms that have been passed through a microwave discharge to provide a source of 16.6-16.85 eV excitation, prominent new infrared absorptions result. These absorptions include the CN-stretching modes of the corresponding cations and absorptions of the uncharged isocyanides. Subsequent exposure of the deposit to various wavelengths of near-infrared, visible, and near-ultraviolet radiation results in a series of changes in the product spectra. The photoprocesses which are responsible for these changes are analogous to photoprocesses which occur for the diatomic halogens, but have the advantage in the XCN studies of yielding infrared-active products.

WI05 15 min 2:38 MATRIX-ISOLATION SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBON (PAH) IONS: HYDROGENATED-PAH CATIONS AND THE PENTACENE IONS THOMAS M. HALASINSKI, FARID SALAMA, LOUIS J. ALLAMANDOLA, NASA Ames Research Center, Mail Stop: 245-6, Moffett Field, CA 94035-1000; and THOMAS BALLY, Institute of Physical Chemistry, University of Fribourg, Perolles, CH-1700 Fribourg, Switzerland. We are currently extending the size, structure, and charge state of polycyclic aromatic hydrocarbons (PAHs) studied spectroscopically in the laboratory to develop a more complete understanding of the physical conditions and the chemical evolution within the interstellar medium. We report here the UV/Visible spectroscopy of a series of PAHs containing excess H atoms (Hn -PAHs) and their photoproducts isolated in a neon matrix and compare them to the spectra of their chromophores. We also report supporting time-dependent density-functional theory (TD-DFT) calculations that allow new and revised assignments for pentacene ions. These calculations indicate that in the specific case of the pentacene cation, the HOMO to LUMO transition leads to the lowest excited electronic state. This is the first time such an effect is reported for the acenes.

180

WI06 SPECTROSCOPY AND RELAXATION KINETICS OF MATRIX ISOLATED CH/D RADICALS

15 min

2:55

AMY BURROUGHS and MICHAEL C. HEAVEN, Department of Chemistry, Emory University, Atlanta, GA 30322. We have investigated the properties of matrix isolated CD and present a comparison with earlier studies of the CH radical. The CH/D radicals were formed by the microwave dissociation of methane. The products were trapped in solid Ar or Kr at 12 K and investigated using laser excitation and dispersed fluorescence techniques. The B2  -X2  and A2
-X2  transitions were studied. The decay of CH(B) v = 0 is primarily radiative in both Ar and Kr with small contributions from B!A nonradiative transfer. Fluorescence was not detected from CD(B), v = 0, as the B!A transfer process was much faster than radiative decay for this isotope. Differences in the B!A energy gaps are responsible for the large difference in the transfer rates of the two isotopes. Excitation spectra yield evidence that CH/D(B) rotates in solid Ar and Kr matrices. Low frequency structure in the B-X (0,0) absorption band changed considerably on H/D isotopic substitution while it was relatively insensitive to the replacement of the matrix material. Absorption spectra for the A-X transition did not show evidence for rotation in the matrix, but it is likely that optical selection rules prevent the observation of rotational structure in this instance. Vibrational relaxation of CH/D(B) is faster for the heavier isotope, indicating that vibration to rotation energy transfer is the dominant relaxation mechanism. Work supported by the National Science Foundation

WI07 15 min 3:12 INVESTIGATION OF lATTICE DYNAMICS AND SYMMETRY OF HYDROGEN-CONTAINING IODATE CRYSTALS BY IR AND NQR METHODS A. BARABASH, Institute of Physics, National Academy of Sciences of Ukraine, 46, Prospect Nauki, 252022 Kiev, Ukraine. The results of investigations of the lattice dynamic and symmetry of the hydrogen-containing iodate crystals in the wide temperature range, including temperatures of the phase transitions, is presented. It was shown, that these crystals have similar structure and have different properties: piezoelectric, ferroelectric, untiferroelectrc, dielectric and other. The observed properties, as it was founded by us in previous works, determine by energy and state of hydrogen bonds, which form unit cell of investigated crystals. The IR spectrum analysis of of these crystals in the hydrogen vibration region was done. It was shown, that center-symmetric crystals due to the existence of symmetric hydrogen bonds with two-minimum proton potential, which form hydrogen net-work, undergo the second type phase transitions. The asymmetric hydrogen bonds can provide the observed first (displace) or second (untiferroelectric) type phase transitions. The analyze of the pressure dependencies of 127 I NQR spectra of these crystals lead to conclusions that all hydrogen bonds, independently on their symmetry, stay more symmetric under hydrostatic pressure (so called by us effect of symmetrization of the hydrogen bonds).

Intermission

181

WI08 NUCLEAR SPIN MODIFICATION OF METHANE IN PARAHYDROGEN CRYSTALS

15 min

3:45

MIZUHO FUSHITANI, MASAAKI MIKI, and TAKAMASA MOMOSE, Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, JAPAN. Solid parahydrogen is an excellent matrix for matrix-isolation spectroscopy because of its high spectral resolution. Here, we report the nuclear spin symmetry selection rule of a chemical reaction CH2 + H2 ! CH4 and the nuclear spin conversion of CH4 embedded in parahydrogen crystals studied by infrared absorption spectroscopy. Due to the nuclear spin modification, not only the J=0 rotational level but also the J=1 level of CH4 is populated even if the temperature is lowered sufficiently. Since conversion among different nuclear spin states is very slow, population ratio between the J=1 and J=0 levels observed just after the crystal growth reflects the ratio of A and F nuclear spin states before the cooling. The vibration-rotation absorption of CH4 in parahydrogen crystal grown from a premixed gas of methane and hydrogen molecules shows the population ratio of approximately (J=1):(J=0)=2:1. On the other hand, CH4 produced by the photochemical reaction of CH3 + H2 + 193nm ! CH2 + H + H2 ! CH4 + H was found to have four times larger population in the J=1 rotational level than in the J=0 level just after the reaction. The former reflects the ratio of the A and F nuclear spin states being 5:9 at room temperature, while the latter is due to a nuclear spin selection rule of the reaction. In addition, the vibration-rotation absorptions of CH4 exhibit time-dependent intensity changes at 4.8K. These changes are interpreted to be a result of the I = 1(F ) ! I = 2(A) nuclear spin conversion which accompanies the J = 1 ! J = 0 rotational relaxation. The half-lifetime of the upper J = 1 rotational state is unchanged by the addition of up to 2% orthohydrogen molecules, but decreases with more than 10% orthohydrogen molecules. The increase of the decay rate at higher orthohydrogen concentration indicates that the magnetic field gradient across CH4 caused by orthohydrogen molecules mixes the nuclear spin states which accelerate the conversion.

WI09 15 min 4:02 ANALYSIS OF FEMTOSECOND PUMP-PROBE SPECTRA IN THE CONDENSED PHASE: DYNAMICS AND POTENTIALS OF I2 IN RARE GAS MATRICES M. BARGHEER, K. DONOVANG, P. DIETRICH and N. SCHWENTNER, Institut fu¨ r Experimentalphysik, Freie Universit¨at Berlin, Arnimallee 14, 14195 Berlin, Germany. We present a scheme to directly extract molecular dynamics and potentials from femtosecond pump-probe-spectra in the condensed phasea . As a model-system we consider the well studied I2 molecule isolated in a Kr matrix, since it shows up to 32 oscillations of the molecule despite relaxation and predissociation. The method can be applied to more complicated systems, if several oscillations of one mode can be measured. It is complementary to sophisticated simulations and yields intuitive understanding of pump-probe spectra. Due to the coupling to many degrees of freedom of the bath atoms, the electronic absorption spectrum is broad and completely unstructured. Using femtosecond pump-probe spectroscopy, the molecular vibrations can be observed in the time domain as oscillations in the LIF-signal. Vibrational frequency, anharmonicity and a rate of energy dissipation can be read directly off the spectra. Using independently tunable pump and probe pulses (from noncollinearly pumped OPAs) we measured a set of spectra covering a wide range of excitations of the B-state. The systematic variation of pump and probe wavelengths allows to seperate predissociation, relaxation, dephasing and dispersion of the molecular wavepacket. Interesting details of the probe process are revealed. a Bargheer,

K. Donovang, P. Dietrich and N. Schwentner, J. Chem. Phys. 111 (1999) 8556-8564

182

WI10 FOURIER TRANSFORM INFRARED SPECTRA OF Gen CLUSTERS TRAPPED IN SOLID Ar

10 min

4:19

S. DEVDAS,C.M.L. RITTBY, AND W.R.M. GRAHAM, Department of Physics and Astronomy, TCU, Fort Worth, TX 76129. The structures and vibrational fundamentals of Gen clusters trapped in solid Ar are under investigation using Fourier transform infrared spectroscopy. Gen anions (n=2 - 15) were studied earlier by Neumark et al.a , using anion photoelectron spectroscopy and zero electron kinetic energy spectroscopy. Tentative assignments were made for a fundamental vibration of each of Ge3 and Ge4 , although vibrational structure was unresolved for larger clusters. We present vibrational spectra obtained for Gen species produced by laser ablation of pure germanium followed by trapping in an Ar matrix and compare the experimental observations with the predictions of density functional theory calculations. a G. R. Burton, C. Xu, C. Arnold, and D. Neumark, J. Chem. Phys. 104, 2757 (1996). WI11 FTIR AND DFT STUDIES OF GERMANIUM-CARBON CLUSTERS

15 min

4:31

D.L.ROBBINS,C.M.L. RITTBY, AND W.R.M. GRAHAM, Department of Physics and Astronomy, TCU, Fort Worth, TX 76129. Fourier transform infrared studies have been intiated on germanium-carbon clusters formed by laser ablation and trapped in solid Ar. The determination of structures and vibrational fundamentals is facilitated by comparison of fudamental frequencies and isotopic shifts with the predictions of density functional theory calculations which are being carried out in concert with the experimental measurements. Of particular interest are comparisons with the previously reported structures and vibrations of a large number of related silicon-carbon clusters. a a X.D. Ding, S.L. Wang, C.M.L. Rittby, and W.R.M. Graham J. Chem. Phys. 110, 11214 (1999) and references therein. WI12 15 min 4:48 SPECTROSCOPIC STUDY OF THE Ga(CH3 )3 PLUS HN3 REACTION SYSTEM IN LOW TEMPERATURE ARGON MATRICES JULANNA V. GILBERT, MATTHEW L. MULCH, Department of Chemistry and Biochemistry, University of Denver, Denver, CO 80208-2435. During the past several years, infrared and UV absorption spectroscopy and low temperature matrix isolation have been used to probe the photolytic mechanisms of Group III-azide systems. These systems have the propensity to decompose to form nitride films, and hence are of considerable practical interest. The first compounds studied were the boron-azide molecules, B(N3 )3 , BCl(N3 )2 and BCl2 N3 , species which can be generated in the gas phase reaction between BCl 3 and HN3 by adjusting the stoichiometic ratio of the reagents. Their photolysis mechanisms were probed by depositing the products of the reaction in low temperature argon matrices and following changes in the IR and UV spectra during broad band photolysis of the matrices.(1,2,3) New photolytic intermediates were identified via their IR spectra. Other Group III-azide systems of interest include the gallium- and the aluminum-azides, and this presentation will report the spectroscopic information obtained for the gallium-azide system using the low temperature matrix isolation technique. Results of previous studies of the gallium-azide reaction system indicated that Ga(CH3 )3 and HN3 do not react in the gas phase.(4) Rather, a slow surface reaction between Ga(CH3 )3 adsorbed on the walls and HN-3 was observed, the rate of which increased upon irradiation at 254 nm. GaN and GaN3 containing species formed on the walls of the reaction vessel. In this presentation, a spectroscopic study of the Ga(CH3 )3 + HN3 reaction system with 254 nm irradiation will be discussed and IR and UV spectra will be reported. 1. I. A. Al-Jihad, B. Liu, C. J. Linnen, J. V. Gilbert, J. Phys. Chem., 1998, 102, 6220. 2. L. A. Johnson, S. A. Sturgis, I. A. Al-Jihad, B. Liu, J. V. Gilbert, J. Phys. Chem. A, 1999, 103, 686. 3. M. J. Travers, E. L. Eldenburg, J. V. Gilbert, J. Phys. Chem. A, 1999, 103, 9661. 4. C. J. Linnen, R. D. Coombe, Applied Phys. Lett., 1998, 72, 88.

183

WI13 THERMOLUMINESCENCE OF IMPURITY-HELIUM SOLIDS IMMERSED IN LIQUID HELIUM

10 min

5:05

R. E. BOLTNEV, E. B. GORDON, V. V. KHMELENKO, I. N. KRUSHINSKAYA, M. V. MARTYNENKO, A. A. PELMENEV, E. A. POPOV, Institute of Energy Problems of Chemical Physics, 142432, Chernogolovka, Moscow Region, Russian Federation; A. F. SHESTAKOV, Institute of Problems of Chemical Physics, 142432, Chernogolovka, Moscow Region, Russian Federation. A solidification of liquid helium around impurity particles injected in its volume results in IHSP (Impurity-Helium Solid Phase) formation a , so these particles can be stabilized with inert environment during long time. Particular interest is stabilization of metastable particles. The capture of N(2 D) atoms from discharge allows to save ones at T=1.5 K during 104 s - time comparable with their lifetime, 4:4  104 s. Nevertheless, even small temperature increase (< 0:1 K) causes the luminescence on the 2 D - 4 S transition. It was explained as thermoactivated association of neighbouring centers of IHSP, N+N2 or N+Rg, which partially removes the prohibition because of ”heavy particle effect” b . The main part of stabilized nitrogen atoms is in the ground state 4 S, so thermoactivated mobility leads to the pair recombination N+N or N+O (O2 presents as trace in condensed gas mixture). The results presented in report confirm that heating of IHSP samples causes a blue emission which can be assigned to excited states of N2 or NO. Acknowledgement: The work was carried out with support from Russian Foundation for Basic Research (Grant 99-0333261). a E.

B. Gordon, V. V. Khmelenko, A. A. Pelmenev, E. A. Popov, O. F. Pugachev, A. F. Shestakov, Chem. Phys. 170, 411 (1993). E. Boltnev, E. B. Gordon, V. V. Khmelenko, I. N. Krushinskaya, M. V. Martynenko, A. A. Pelmenev, E. A. Popov, A. F. Shestakov, Chem. Phys. 189, 367 (1994). b R.

WI14 ODMR OF ATOMS TRAPPED IN IMPURITY-HELIUM SOLID. a

10 min

5:17

E.A. POPOV, R.E. BOLTNEV, E.B. GORDON, A.A. PELMENEV, Institute of Energy Problems of Chemical Physics, Russian Academy of Sciences, 142432, Chernogolovka, Moscow Region, Russia; Yu.A. DMITRIEV, A.F. Ioffe Physico-Technical Institute, St. Petersburg, 194021, Russia; A. WEIS, S. LANG, Institute of Applied Physics, Bonn University, 53115 Bonn, Germany. Metastable N(2 D) atoms are stabilized in an aerogel-like medium, soaked by superfluid helium (HeII), and called ImpurityHelium Solid (IHS), showing strong thermoluminescence in the range of 1.4 to 4.0 K on the 2 D-4 S transition (523 nm). Even slight increase in temperature (less than 100 mK) leads to significant rise in luminescence. We used IHS as a specific optical bolometer for monitoring of magnetic resonance (ODMR) of paramagnetic atoms, trapped in IHS and detected for the first time ODMR of ground state N(4 S) atoms upon CW microwave incident on the sample and slow sweep of magnetic field. On passing through resonance the sample absorbed microwave radiation and, as a result of spin-lattice relaxation was heated large enough for excitation of luminescence and optical detection of magnetic resonance. Recently we have managed to excite blue luminescence of Kr- and Ar- IHS samples, containing diluted amounts of atomic nitrogen by applying a short heat pulses to the sample directly in HeII. The observed luminescence was found to decay at  427 nm with characteristic time  less than 10 msec. We have been improving the sensitivity of this ODMR approach by employing a pulsed microwave radiation with subsequent synchronous detection of luminescence. The method proposed is expected to be universal for optical monitoring of magnetic resonance of any paramagnetic species, trapped in IHS due to non-specific nature of excitation of luminescence. a Supported

by RFBR Projects 98-03-33095, 98-03-32283, 99-03-33261

184

RA. ELECTRONIC (SMALL) THURSDAY, JUNE 15, 2000 – 8:30 AM Room: 1153 SMITH LAB Chair: JEFF GRAY, Ohio Northern University, Ada, OH

RA01

15 min

QUANTITATIVE ANALYSIS OF NON-ADIABATIC PREDISSOCIATION OF Li2 (F

8:30

1 + ) g

ROBERT J. LE ROY and GEOFFREY T. KRAEMER, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Extensive recent measurementsa of the widths of predissociating levels of the F (4) 1 + g state of Li2 are analysed within states. The coupling operator driving the an adiabatic description of the interstate mixing of the F (4) and E (3) 1 + g  d  , where each W (R) function is a predissociation is the sum of two terms of the form ( h2 =2) 2 We0 (R) + We (R) dR e Lorentzian centred at one of the avoided crossings between the adiabatic F – and E –state potential energy curves.b Application of an updatedc version of photodissociation code BCONT d allows the parameters of the two Lorentzians defining this coupling operator to be quantitatively determined from a direct least-squares fit to the 274 measureda line widths for 7;7 Li . 2 a b c d

S. Antonova, G. Lazarov, K. Urbanski, A. M. Lyyra, L. Li, G.-H. Jeung and W. C. Stwalley, J. Chem. Phys. 112 (2000). A. Bandrauk and M. S. Child, Mol. Phys. 19, 95 (1970). R. J. Le Roy, http://theochem.uwaterloo.ca/ ~leroy (2000). R. J. Le Roy, Comp. Phys. Comm. 52, 383 (1989).

RA02

15 min 1 + DIRECT-POTENTIAL-FIT DETERMINATION OF THE LiH (C  ) DOUBLE MINIMUM POTENTIAL

8:47

JENNING Y. SETO and ROBERT J. LE ROY, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Empirical analyses of data involving states whose potential energy curves have double or multiple minima tend to be fragmentary or approximate, since conventional molecular constant expressions cannot describe their level energy patterns. The only accurate quantal way of analysing such data is to perform direct fits of the data to analytic expressions for the underlying potential energy curves. This paper describes our direct-potential-fit (DPF) analysis of recently publisheda data for the C 1 + state of LiH which is knownb to have a shallow second potential well lying near dissociation on the inner potential wall. The resulting potential has the “MLJ” form V (R) = De [1 (Re =R)n e (z ) z ]2 , where z = (R Re )=(R + Re ) and (z ) is a power series in z which has smooth monotonic behaviour across the region where the potential oscillates to support the two minima.c a b c

J.-J. Chen, W.-T. Luh and G.-H. Jeung, J. Chem. Phys. 110, 4402 (1999) A. Boutalib and F. X. Gad´ea, J. Chem. Phys. 97, 1144 (1992) P. G. Hajigeorgiou and R. J. Le Roy, J. Chem. Phys. 112, 3949 (2000).

185

RA03

15 min

9:04 DIRECT-POTENTIAL-FIT DETERMINATION OF AN ACCURATE ANALYTICAL POTENTIAL FOR THE F (4) 1 + g

“SHELF” STATE OF Li2

YIYE HUANG and ROBERT J. LE ROY, Guelph-Waterloo Centre for Graduate Work in Chemistry and Biochemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. The F (4) 1 + state of Li2 is known to have an unusual shape because of two (or three) avoided crossings with other states of the same symmetry. One of these avoided crossings gives rise to a well defined “shelf” in the effective adiabatic potential curve, which makes analysis of data for this state by traditional methods quite difficult, since conventional molecular constant expressions cannot describe the resulting level energy patterns. Recent experimental results a have yielded precise measurements of selected vibration-rotation levels of this state spanning almost the entire interval from the potential minimum to dissociation. The present paper describes our use of “direct-potential-fit” (DPF) methods to quantitatively reanalyse those data and determine an accurate analytic potential energy function for this shelf-state system. a

S. Antonova, G. Lazarov, K. Urbanski, A. M. Lyyra, L. Li, G.-H. Jeung and W. C. Stwalley, J. Chem. Phys. 112 (2000).

RA04

10 min

OBSERVATION OF HIGH LYING LEVELS OF THE 1g

9:21

11 g STATE OF K2

A. J. ROSS, F. MARTIN and I. RUSSIER-ANTOINE, Laboratoire de Spectrom´etrie Ionique et Mol´eculaire (UMR 5579 CNRS), Bˆatiment 205, Universit´e Lyon I, Campus la Doua, 69622 Villeurbanne Cedex, France; H. M. CHEN, M. PICHLER, H. WANG and W. C. STWALLEY, Department of Physics, University of Connecticut, Storrs, CT 06269-3046, U.S.A. Very high-lying vibrational levels 87  v” 138 of the 1g 11 g electronic state of K2 have been observed in a photoassociation experiment performed in Connecticut, using ionization detection. Photoassociation of ultracold potassium atoms furnishes accurate binding energies for J  4 in these levels. These binding energies have been treated with laser induced fluorescence data covering the levels 0  v”105 at high J (infrared C 1 u ! 1 1 g transitions recorded by Fourier transform spectrometry) to construct an accurate potential curve for this electronic state. Because several vibrational levels were observed both in photoassociation and in fluorescence, an experimental dissociation energy can be deduced from the sum of binding energies (measured in photoassociation) and vibrational energies established with respect to the potential minimum (from fluorescence data), giving De = 1230.297  0.002 cm 1 . Applying asymptotic models for the interactions between K(4s) + K(4p) atoms to the molecular potential energy curve, a slightly lower value, 1230.292  0.002 cm 1 is obtained. This is considered to be the best available value for the dissociation energy of the 1 1 g electronic state into K(4s) + K(4p)2 P3=2 atoms.

186

RA05 FOURIER TRANSFORM INFRARED EMISSION SPECTROSCOPY OF SeH

15 min

9:33

R. S. RAM, Department of Chemistry, University of Arizona, Tucson, AZ 85721; P. F. BERNATH, Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1.

Intermission

RA06 THE ELECTRONIC SPECTRA OF LaNH AND LaND

15 min

10:10

DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; ANTHONY J. MERER, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1; SCOTT J. RIXON, Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC, Canada V6T 1Z1; THOMAS D. VARBERG, Department of Chemistry, Macalester College, St. Paul, MN 55105. Electronic bands of the new molecules LaNH and LaND have been observed by laser-induced fluorescence following the reaction of laser-ablated La metal with NH3 or ND3 under supersonic jet-cooled conditions. High-resolution data for LaNH show that the ground state is 2 + (b S ) with B 0 = 0:305478 (22) cm 1 . Extensive dispersed fluorescence data have given ground state vibrational frequencies for LaNH (LaND):  2 (bend) = 462 (354) cm 1 and  3 (La-N stretch) = 755 (744) cm 1 . Two electronic systems with origins near 658 and 823 nm, both of which appear to have 2  upper states, have been identified from spectra in the 525 875 nm region.

187

RA07 15 min 10:27 PHOTOFRAGMENTATION SPECTROSCOPY OF NIOBIUM CATION CLUSTERS IN A REFLECTRON TIME-OFFLIGHT (TOF) MASS SPECTROMETER AND DENSITY FUNCTIONAL CALCULATIONS ON NIOBIUM CATION CLUSTERS M. AYDIN, D. M. LINDSAY, J. R. LOMBARDI, Department of Chemistry and Center For Analysis of Structure and Interfaces (CASI), City College of New York of City University of New York 137th. Street and Convent Ave. New York, NY 10031. The dissociation energies of niobium dimer and tetramer cation clusters are presented. The clusters are produced by laser vaporization of a niobium target rod and cooled in a helium supersonic expansion. The molecular beam containing niobium cation clusters are interrogated in the range 15,400-18,440 cm 1 using a pulsed dye laser to dissociate the cluster. The dissociation thresholds of the niobium dimer and tetramer cations were determined to be 5:9070:056 eV and 5:9900:004 eV, respectively, in agreement with other experiments.ab Several density functional calculations predicted the dissociation energy of niobium dimer, trimer and tetramer cation clusters and the first ionization energy of Nb2 , Nb3 , and Nb4 in remarkable agreement with experiments. a David. b J.

A. Hales, Li Lian, and P. B. Arementrout, Int. J. Mass Spect. And Ion Processes. 102, 269 (1990). M. W. Chase, C. A. Davies, J. J. R. Downey, D. J. Frurip, R. A. McDonald, and A. N. Syvrud, J. Phys. Chem. Ref. Data Suppl. 14, 1 (1985)

RA08

10 min

VIBRATIONAL STRUCTURE IN THE B4 

10:44

X 4  ELECTRONIC TRANSITION OF NbO

NING FANG, CHRISTOPHER T. KINGSTON, DAVID C.K. LIAO, ANTHONY J. MERER and SHUENNJIUN TANG, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1. During our studies of niobium methylidyne, NbCH, we were continually faced with the presence of the much stronger and frequently overlapping niobium oxide spectrum. This motivated us to begin a thorough investigation of NbO throughout the visible region in order to document the somewhat irregular nature of the vibrational structure of its electronic spectrum. X 4  electronic transition were recorded at high resolution. Two (3,1) The (n,0) bands, where n=1, 2, 3, of the B4  4 X 4 3=2 and B4 1=2 X 4 1=2 sub bands were also studied using hot band transitions corresponding to the B  1=2 high resolution methods. The vibrational dependencies of the rotational and hyperfine structure as well as other interesting aspects of the spectra will be presented.

188

RA09 ˜ 2 + , A ˜ 2 HIGH RESOLUTION STUDY OF THE B˜ 2 + X 14 15 14 TRIUM IMIDE (Y NH, Y NH, AND Y ND).

˜ 2 + , AND A ˜ 0 2 3=2 X

15 min 10:56 2 + ˜  SYSTEMS OF YTX

ZYGMUNT J. JAKUBEK AND BENOIT SIMARD, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6; HIDEAKI NIKI, Electrical and Electronics Engineering, Fukui University, Fukui-shi, Fukui 910, Japan; WALTER J. BALFOUR, Department of Chemistry, University of Victoria, Victoria, BC, Canada V8W 3V6. ˜ 2 + , A ˜ 2 + , and A ˜ 2 + (0,0,0 ˜ 2 X ˜ 0 2 3=2 X Results of high resolution molecular beam studies of the B˜ 2 + X 0,0,0) transitions in yttrium imide are reported. Preliminary analysis of several transitions between Renner-Teller vibronic states is also presented. Three isotopomers (Y14 NH, Y15 NH, and Y14 ND) are investigated. The YNH molecules are produced by laser ablation of yttrium metal in the presence of ammonia diluted in helium gas (1-2%). Molecules are excited by a ring dye laser and laser induced fluorescence is detected. The spectra are very complicated due to multiple perturbations in the upper states and nuclear magnetic hyperfine structure in the ground state. The hyperfine structure arrises from the interaction of the unpaired  electron with the 89 Y nucleus. Some of the perturbers are assigned to vibronic states originating from low-energy electronic states and others are treated as effective perturbers. The spectra ˜ 2 , A ˜ 0 2 3=2 , and X ˜ 2 + are deperturbed and accurate molecular constants for the zero-vibration levels of the B˜ 2 + , A electronic states as well as some of the perturbers are obtained. The yttrium imide is found to have the linear Y-N-H structure in the four electronic states studied in this project. The bond lengths (r0 ) are determined to be:

rY N [nm] X~ 2 + 0:187785 (17) A~2  0:1894 (10) B~ 2 + 0:18848 (52)

rNH [nm] 0:10039 (14) : 0:1112 (95) 0:1236 (46)

The results are discussed and related to isovalent diatomic and triatomic molecules (YO, ScNH).

RA10 NEAR INFRARED LASER SPECTROSCOPY OF VS

15 min

11:13

QIN RAN, W. S. TAM, A. S-C. CHEUNG, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong; A. J. MERER, Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B.C. V6T 1Z1, Canada.

189

RA11 NEAR INFRARED LASER SPECTROSCOPY OF CrS

10 min

11:30

QIANG SHI, QIN RAN, W. S. TAM, J. W-H. LEUNG, A. S-C. CHEUNG, Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong.

RA12 15 min 11:42 AN AB INITIO MOLECULAR ORBITAL STUDY OF LOW LYING ELECTRONIC EXCITED STATES OF FeC SACHIKO S. ITONO, TETSUYA TAKETSUGU, TSUNEO HIRANO, Department of Chemistry, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan; UMPEI NAGASHIMA, National Institute for Advanced Interdisciplinary Research, Ibaraki 305-8562, Japan; K. AIUCHI, K. TSUJI, and K. SHIBUYA, Department of Chemistry, Graduate School of Science and Engineering, Tokyo Institute of Technology, Tokyo, 152-8551, Japan. Spectroscopic constants and energy levels of the ground and low-lying excited states of iron carbide, FeC, have been calculated from potential energy functions obtained by the ab initio MR-SDCI molecular orbital approach. Investigated states are 1
and 5 , both of which are proposed by DF spectraa as a candidate for the new = 2 electronic state observed above the 3
2 state by 3460 cm 1 . The character of each electronic state has been discussed theoretically. Contrary to the previous tentative assignment to 5 , the MR-SDCI results predict that the observed = 2 state should be the 1
state and be located at 3252 cm 1 above 3
2 . The spin-orbit coupling constant for 3
state has also been calculated. a K.

Aiuchi, K. Tsuji and K. Shibuya Chem. Phys. Lett. 309, 229, (1999)

190

RB. JET AND BEAM THURSDAY, JUNE 15, 2000 – 8:30 AM Room: 1009 SMITH LAB Chair: LAURI HALONEN, University of Helsinki, Helsinki, Finland

RB01 15 min 8:30 HIGH-LYING RYDBERG STATES AND IONIZATION POTENTIAL OF VINYL CHLORIDE STUDIED BY TWOPHOTON RESONANT IONIZATION SPECTROSCOPY JIA-LIN CHANG, JAU-CHIN SHIEH, RUNHUA LI, JEN-CHIEH WU and YIT-TSONG CHEN, Department of Chemistry, National Taiwan University, Taipei 106, Taiwan, and Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan. High-lying Rydberg states of jet-cooled vinyl chloride (C2 H3 Cl) at 7.5-10 eV have been observed using 2+1 resonanceenhanced multiphoton ionization (REMPI) spectroscopy. The vibronic transitions in the ranges of 62500-65000 cm 1 , 67000-70000 cm 1 and 70000-72500 cm 1 are attributed to  !3p,  !3d/nCl !3s and  !4p excitations according to the previous assignment by Williams and Cool.a Comprehensive analysis for the vibronic transitions is facilitated with the calculation of Franck-Condon factors based on our recently developed theoretical method.b Four Rydberg series at 9.5-10 eV are newly observed and tentatively assigned as due to the promotion of a  -electron to the ns (n = 8-13, 20), np (n = 7-11, 18), np0 (n = 6, 7, 10-18, 21) and nf (n = 6-16) Rydberg orbitals. All the four Rydberg series converge to the same limit, i.e. the ground state of vinyl chloride cation. The term values of the nf Rydberg series, fitted to Rydberg formula, provide a very accurate adiabatic ionization energy, 80718  2 cm 1 , for vinyl chloride with a quantum defect of Æ = 0.02. a B. b A.

A. Williams and T. A. Cool, J. Phys. Chem., 97, 1270 (1993). M. Mebel, Y. -T. Chen and S. H. Lin, J. Chem. Phys., 105, 9007 (1996).

191

RB02 15 min 8:47 STRUCTURE AND MOLECULAR DYNAMICS OF THE HYDROGEN-BONDED PHENOL-METHANOL COMPLEX FROM HIGH RESOLUTION ELECTRONIC SPECTROSCOPY AND AB INITIO THEORY.a ¨ JOCHEN KUPPER, ARNIM WESTPHAL, MICHAEL SCHMITT and KARL KLEINERMANNS, HeinrichHeine-Universit¨at, Institut f¨ur Physikalische Chemie und Elektrochemie I, 40225 Du¨ sseldorf, Germany. The rotationally resolved spectrum of the electronic origin of the hydrogen bonded phenol-methanol cluster in a molecular beam at 35933 cm 1 has been analyzed. Due to the internal rotation of the methyl group in the methanol moiety the spectrum is split into A and E sub-torsional bands separated by 3.558 GHz. From a perturbation analysis of the torsionalrotational structure the V3 =F values of the threefold barriers to internal rotation of the methyl group could be determined to be 32:16 in the S0 and 27:65 in the S1 state, respectively. The determination of barrier heights from these ratios is discussed, and the obtained barrier heights are compared to bare methanol and other methanol clusters. The perturbation analysis also yields the angle between the internal rotor axis and the inertial axes of the cluster, which allows the determination of the geometry of the hydrogen bond in both electronic states. From the obtained data parameters of the intermolecular structure of the cluster as well as for the torsional potential of the methyl rotation are determined. The structure, energetics and barrier to internal rotation of the cluster are calculated at different levels of theory (HF, DFT, and MP2) and compared to the experimental results. The structure of the phenol-methanol cluster is determined by the hydrogen bonding interaction and the (mostly) dispersive interaction of the methyl group with the aromatic ring. To account for the correct balance between these two attractive forces, methods have to be employed which include electron correlation. Furthermore ab initio normal mode analyses are compared to experimental intermolecular vibrational frequencies for both electronic states. The results obtained for phenol-methanol are compared to the phenol-water cluster,a in which also the phenol moiety acts as proton donor. This cluster shows distinct differences to the phenol-methanol cluster in structure and molecular dynamics and the reasons for these different behaviours are discussed. a Work a G.

supported by DFG. Berden, W.L. Meerts, M. Schmitt and K. Kleinermanns, J. Chem. Phys. 104(1996), 972

RB03 THE HIGH RESOLUTION S1

15 min 9:04 S0 SPECTRUM OF THE ANISOLE-WATER COMPLEX: WATER AS AN ACID. a

JASON W. RIBBLETT, Department of Chemistry, Ball State University, Muncie IN 47302; DAVID R. BORST, and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. The rotationally resolved S1 S0 electronic spectra of anisole and the 1:1 anisole-water complex have been recorded in a molecular beam. This is the first rotationally resolved electronic spectrum recorded in which water acts as an acid and the chromophore acts as base. The spectrum is split into two subbands separated by 730 MHz, having an intensity ratio of 3:1. This indicates that the water hydrogens are exchanged by a low barrier tunneling motion. The nature of this motion will be discussed. a Work

supported by NSF.

RB04 BENZONITRILE AND ITS WATER COMPLEX: THE S1

15 min 9:21 S0 SPECTRUM AT ROTATIONAL RESOLUTION. a

DAVID R. BORST and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. The high resolution S1 S0 electronic spectrum of benzonitrile-water has been recorded in a molecular beam. The spectrum is split into two subbands with a 3:1 intensity ratio separated by 53 MHz. Analysis of this splitting leads to values of the barrier height in both electronic states. The barrier and the position of the water molecule will be used to discuss the bonding between the two subunits. Analysis of other benzonitrile complexes and of the change in the benzonitrile dipole moment upon excitation will be used to further characterize the structure of the complexes in both electronic states. a Work

supported by NSF.

192

RB05 HIGH RESOLUTION SPECTRUM OF THE 1,2-DIMETHOXYBENZENE/D2 O COMPLEX a

15 min

9:38

JOHN YI and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh PA 15260. The rotationally resolved S1 S0 electronic spectrum of the 1,2-dimethoxybenzene/D2 O complex has been analyzed. The D2 O complex appears 126 cm 1 to the blue of the bare molecule origin. The complex spectrum exhibits two subbands separated by 45 MHz. These spectra have an intensity ratio of 2 to 1, with the stronger band shifted to lower frequency. Possible motions of the water molecule that are suggested by these data will be discussed. a Work

supported by NSF

RB06 15 min 9:55 A HIGH RESOLUTION ELECTRONIC SPECTRUM OF THE PARA-DIFLUOROBENZENE/WATER COMPLEX a CHEOLHWA KANG and DAVID W. PRATT, Department of Chemistry, University of Pittsburgh, Pittsburgh, PA 15260. The rotationally resolved S1 S0 fluorescence excitation spectrum of para -difluorobenzene (p DFB) / water complex has been observed. The water complex appears 169 cm 1 to the blue of the bare molecule origin and is split into two spectra separated by 0.12 cm 1 .These spectra are a result of the internal rotation of the water molecule in the complex. Analyses of the bands show that the water molecule lies in the ab plane of the p DFB molecule. The possible types of water motion will be discussed. a work

supported by NSF

Intermission

RB07 SPECTROSCOPY AND STRUCTURE OF A HYDROGEN BONDED CIS AMIDE DIMER

10 min

10:30

A. V. FEDOROV, J. R. CABLE, Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403. Electronic spectra of the dimer of the cis amide oxindole and the complex of oxindole and formamide have been obtained in a supersonic jet expansion using mass-resolved resonant two-photon ionization spectroscopy. The experimental results are supportive of cyclic hydrogen bonded structures for both complexes. The oxindole chromophores in the dimer are equivalent and statistical deuteration reveals a small exciton splitting, indicative of an essentially localized excitation. Spectra of the oxindole dimer hydrated with one and two water molecules have also been obtained and have been interpreted by comparison to the dimer spectrum in conjunction with ab initio Hartree-Fock calculations.

193

RB08 15 min 10:42 ELECTRONIC SPECTROSCOPY OF TWO N-PHENYL CIS AMIDES AND THEIR HYDROGEN BONDED CLUSTERS WITH WATER AND AMMONIA A. V. FEDOROV, J. R. CABLE, Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403; JOEL CARNEY, T. S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907. Electronic spectra of two N-phenyl amides in which the amide group is constrained to a cis configuration by incorporation into a five- or six-membered rings as well as their clusters with water and ammonia have been obtained in a supersonic jet expansion using mass resolved resonant two photon ionization spectroscopy (R2PI). Based on both spectral shifts of the electronic origin transitions and the results of statistical deuteration experiments, the single water clusters are assigned to a cyclic structure where water interacts strongly with both the NH and CO sites of the amide. The single ammonia complexes are also found to adopt cyclic, doubly hydrogen bonded structures that, in contrast, contain strong NH–N and weak NH–O hydrogen bonds. Complexes containing up to two ammonia molecules and up to three water molecules have also been assigned to cyclic structures containing hydrogen bonds at both sites of the amide group. In addition, R2PI spectra of the ternary mixed clusters containing both a water and an ammonia molecule have been recorded. RB09 15 min 10:59 RESONANT ION-DIP INFRARED SPECTROSCOPY OF TWO N-PHENYL CIS AMIDES AND THEIR HYDROGEN BONDED CLUSTERS WITH WATER AND AMMONIA JOEL CARNEY, T. S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907; A. V. FEDOROV, J. R. CABLE, Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43403. One-color, mass-resolved R2PI based resonant ion-dip infrared (RIDIR) and IR-UV hole-burning spectroscopies have been used to identify and assign the structures of the water and ammonia hydrogen bonded clusters of two N-phenyl cis amides in a supersonic jet expansion. The frequency shifts and intensities of the OH and NH fundamental vibrations allow unambiguous identification of vibronic features belonging to different clusters and permit detailed structural assignments to be made. Experimental RIDIR spectra and structural assignments will be discussed with an emphasis on the comparison of single water and ammonia clusters and on the structural alternatives for the ternary mixed clusters of the cis amides containing both water and ammonia. RB10 15 min 11:16 IR-PIRI AND IR-PHOTODISSOCIATION SPECTROSCOPY PERFORMED ON AROMATIC IONS AND HYDROGEN-BONDED CLUSTERS M. GERHARDS, C. UNTERBERG, A. JANSEN, K. KLEINERMANNS, H.-Heine Universit a¨ t D¨usseldorf, Institut f¨ur Physikalische Chemie I 40225 D¨usseldorf, Germany. The new developed IR-PIRI (IR-Photo Induced Rydberg Ionization) spectroscopy can be used to investigate CH-, NH-, and OH-stretching vibrations of aromatic cations and hydrogen-bonded clusters. IR-PIRI spectroscopy is a MATI (MAss Threshold Ionization) depletion method, i.e. the Rydberg neutrals contributing to a MATI signal can be autoionized by exciting CH-, NH-, and OH-stretching vibrations of the ionic core. The knowledge of these vibrational frequencies lead to important information on structure and reactivity of the cation. IR-PIRI spectroscopy offers the possibility to perform a state selective spectroscopy of the cation, since different vibrational levels of the ion can be obtained by MATI spectroscopy. In case of (larger) clusters which cannot be investigated by MATI spectroscopy the CH-, NH-, and OH-stretching vibrations of the ions can be obtained by resonant IR-Photodissociation spectroscopy. Using this method the ions are generated by a resonant R2PI (Resonant 2-Photon Ionization) process which is mass and isomer selective with respect to the neutral cluster. The ionic cluster dissociates after resonant excitation of CH, NH-, or OH-stretching vibrations. IRPIRI and IR-Photodissociation spectroscopy have been applied to the ions of different substituted benzenes, indole and the corresponding hydrogen-bonded clusters with water.

194

RB11 15 min 11:33 THE INFRARED SPECTROSCOPY OF STRONGLY H-BONDED DIMERS: A NEW LOOK AT AN OLD PROBLEM GINA M. FLORIO, CHRISTOPHER J. GRUENLOH, and TIMOTHY S. ZWIER, Department of Chemistry, Purdue University, West Lafayette, IN 47907-1393. Fluorescence-dip infrared spectroscopy (FDIRS) has been used to record the infrared spectra of several strongly H-bonded dimers cooled in a supersonic jet. The strong hydrogen bonds present in these dimers are known to produce intense, extremely broad infrared bands, complete with sub-structure which has been the subject of much previous investigation. By cooling the dimers in the supersonic expansion, much of the breadth and sub-structure of the bands are removed, but the bands nevertheless retain significant breadth and partially resolvable sub-structure that has not been observed previously. In this talk we will present the fluorescence-dip infrared spectra of pyridone dimer and benzoic acid dimer, both with and without partial deuteration. The shape and sub-structure of these bands will be discussed in light of the strong anharmonic couplings present in the dimers. Density functional theory calculations have been used to model the hydride stretch potential and to isolate the strong anharmonic couplings that appear to dominate the appearance of the hydride stretch absorption. RB12 THE 3m VIBRATION-TORSION-ROTATION ENERGY MANIFOLD OF METHANOL

15 min

11:50

LI-HONG XU, M. ABBOUTI TEMSAMANI, Department of Physical Sciences, University of New Brunswick, N.B. Canada E2L 4L5; X. WANG, Y. MA, A. CHIROKOLAVA, T. J. CRONIN, and D. S. PERRY, Department of Chemistry, University of Akron, Ohio 44325-3610. The 3m spectrum of methanol is an important gateway to the understanding of molecular dynamics and to the modeling of cometary spectra. The region is extremely complicated due to a dense vibrational structure and network of interactions among the three CH-stretch fundamentals, 2 , 9 , 3 , six overtones and combinations of the three CH3 -bending modes, 4 , 10 , 5 , and a variety of overtone combinations of the torsion 12 , with the remaining lower-lying vibrations. We have obtained FT spectra for the 3m region under various conditions. The structure is dense with few easily recognized features above the 3 symmetric CH-stretch. However, in an extension of the color-center-laser slit-jet beam spectrum from 2945 to 2975 cm 1 , low K states could be identified, then allowing further assignment and confirmations of the medium K states from FTS. Altogether, about 25 vibration-torsion-K-rotational states have now been firmly assigned up to K = 4. Plots of K-reduced energies place these states into three distinguishable groups assigned as  9 , 24 , and 4 +10 , although there are a number of extra subbands in the spectrum arising possibly from interactions with other states. Spectroscopic findings at the present time are: (i) the torsional A/E ordering is inverted for 9 , normal for 24 , and apparently normal for the presently observed K = 2 states of 4 +10 ; (ii) the K = 0 torsional A/E splittings are -5.48 and 8.28 cm 1 for 9 and 24 , respectively, and an estimated much lower than ground state value for the 4 +10 combination; (iii) the 9 and 24 states have virtually identical upper state term values around 3092 cm 1 , but show almost equal and opposite linear shifts with K with slopes of 2-3 cm 1 /K-value; (iv) the 4 +10 combination is about 20 cm 1 lower in energy than 9 and 24 , 10 cm 1 lower than the previous estimates for the band center.

195

RC. RADICALS AND IONS THURSDAY, JUNE 15, 2000 – 8:30 AM Room: 1000 McPHERSON LAB Chair: C. WELDON MATHEWS, The Ohio State University, Columbus, OH RC01 15 min 8:30 PHOTOIONIZATION OF HOCO RADICAL: A NEW UPPER LIMIT TO THE ADIABATIC IONIZATION ENERGY AND LOWER LIMIT TO THE ENTHALPY OF FORMATION BRANKO RUSCIC, MARITONI LITORJA, CHENGBIN XU and HAIRONG SHANG, Chemistry Division, Argonne National Laboratory, Argonne, IL 60439. HOCO radical is important in combustion and atmospheric chemistry. A recent photoionization investigation provides a new value for the adiabatic ionization energy of EI(t-HOCO) 8.1950.022 eV. Through the positive ion thermochemical cycle, this translates into a lower limit to the enthalpy of formation,
HfÆ0 (t-HOCO) -45.80.7 kcal/mol (-46.50.7 kcal/mol at 298 K), placing t-HOCO only 3.50.7 kcal/mol below the CO2 +H asymptote. The photoionization spectrum of HOCO corroborates the previous finding of a progression in the double C=O bond stretch of the ion of 2300 cm 1 , suggests the presence of the single C-O bond stretch of 1200-1300 cm 1 , and provides indirect evidence for the excitation of an even lower frequency, such as the OCO bend. In addition, the data tentatively suggest an ionization onset as low as 8.060.03 eV. While it is not quite clear whether the latter should correspond to the cis or trans isomer, it may indicate that the enthalpy of formation of HOCO is even higher. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, under Contract No. W-31-109-ENG-38. RC02 15 min 8:47 ON THE CORRELATION BETWEEN PHOTOELECTRON ENERGY AND BENDING EXCITATION IN MOLECULAR PHOTOIONIZATION J. SCOTT MILLER, ERWIN D. POLIAKOFF, Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803. A frequent topic in vacuum ultraviolet spectroscopy is the correlation between electronic and nuclear degrees of freedom when a photoelectron is ejected. However, there have been no previous investigations that have probed the correlation between the bending vibration and the photoejection dynamics over a wide spectral range. We report on the first such study. In order to acquire data over a broad range, we use dispersed fluorescence spectroscopy. Specifically, we report on the influence of bending on the photoionization dynamics following ejection of an electron from the 3 u orbital of CO2 and the 7 orbital of N2 O. These studies are performed over a broad spectral range (18 eV  h exc  190 eV excitation energy for CO2 , 16 eV  h exc  160 eV for N2 O), and features persist over these extended ranges. We employ vibrationally resolved dispersed fluorescence following photoionization using tunable synchrotron radiation to determine the v+ = (0,1,0) / v+ = (0,0,0) vibrational branching ratio for CO2 + B 2 u + and N2 O+ A 2 + ionic states. We find that the extent of bending excitation varies over a broad range, and in ways that are largely unanticipated. These branching ratios exhibit a strong thermal dependence, and we are able to separate out effects due to hot-band excitation from those that are due to vibronic coupling. The extent over which these changes occur underscore the necessity of broad range studies to elucidate slowly varying characteristics in molecular photoionization (such as contributions from a continuum electron). In the N2 O study, the branching ratio displays changes of a factor of two in the branching ratio in the near threshold region due to the presence of shape resonant phenomena in this photoionization channel. For CO2 3 u photoionization, deviations in the vibrational branching ratio persist from near threshold to more than an order of magnitude above threshold. The data indicate that the continuum electron is involved in the vibronic coupling responsible for the observed energy dependence in CO2 3 u photoionization. To our knowledge, vibronic coupling involving a continuum photoelectron channel has not been reported previously, and implications for future studies are discussed. Acknowledgement: This work supported by NSF Grant CHE-9616908.

196

RC03

15 min 9:04 + + A THEORETICAL INVESTIGATION OF THE CLUSTER IONS Xe


HCO , Xe


HNN AND Xe


HNCH+ P. BOTSCHWINA, Institut f¨ur Physikalische Chemie, Universita¨ t G¨ottingen, Tammannstrasse 6, D-37077 G¨ottingen, Germany; H. STOLL, Institut f¨ur Theoretische Chemie, Universita¨ t Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany.

RC04 THE FORMATION MECHANISMS OF D3 : AN INFRARED SPECTROSCOPIC INVESTIGATION

15 min

9:21

T. AMANO, Institute for Astrophysics and Planetary Sciences, Ibaraki University, Mito, Japan 310-8512; MAN-CHOR CHAN, Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong. In 1993, we reported observations of the infrared absorption spectra of D3 with a difference frequency laser system in the frequency ranges around 3600 cm 1 (3s2 A01 3p2 E 0 ) and 3900 cm 1 (3d 3p2 E 0 )a . The observed line shapes exhibited a broad non-Maxwellian velocity distribution, and the line shapes depended on the rotational states. At that time, the line shapes and the widths were not completely understood. Here we present a more detailed and consistent analysis. Most lines of the 3600 cm 1 band appear to be a superposition of two components , broader and narrower features, for some transitions with an opposite phase. From a broader flat-topped line profile, it is concluded that D3 carries excess translational energy of 0.4 eV and is formed through the dissociative recombination reaction of D+ 5 with electrons. The rotational dependence of the line shapes of the 3600 cm 1 band is brought about by a competition between the predissociation in the 3s2 A01 state and the radiative decay in the 3p2 E 0 state. The shorter lifetimes of the 3d complex make the line shape of the 3900 cm 1 band simpler, a superposition of two absorption profiles with different widths. It is found that the widths of the lines of the 3900 cm 1 band are larger than those for the 3600 cm 1 band lines. The greater widths of the 3900 cm 1 band are attributed to unresolved spin-splittings. Attempts to observe similar absorption lines of H3 were unsuccessful, presumably due to much shorter lifetimes. a T.

Amano and Man-Chor Chan, paper TD02, 48th International Symposium on Molecular Spectroscopy, Columbus, Ohio, 1993

RC05

15 min

9:38

1 SURVEY OF H+ 3 TRANSITIONS BETWEEN 3000 AND 4200 CM

C. MICHAEL LINDSAY, RONALD M. RADE and TAKESHI OKA, Department of Chemistry, Department of Astronomy and Astrophysics, and the Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637. 1 Most of a large gap in the laboratory ro-vibrational spectrum of H+ 3 around 3800 cm has been filled using a recently computer controlled color center laser spectrometer which scans between 3000 and 4200 cm 1 . A liquid nitrogen cooled a He/H2 discharge is used to produce rotationally cool, yet vibrationally hot H+ 3 . Variational calculations predict that roughly 300 new lines from the fundamental, the first overtone, combination, and hot bands may be observable with the sensitivity of our spectrometer. The results of this survey will be reported and compared to the theoretical calculations. a J.

K. G. Watson, private communication.

Intermission

197

RC06

15 min

10:10

INFRARED SPECTRA OF H2 O+ -Arn COMPLEXES (n=1-14) OTTO DOPFER, DORIS ROTH, and ROUSLAN V. OLKHOV, Institut f¨ur Physikalische Chemie, Universita¨ t Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland. IR spectra of the open-shell ionic H2 O+ -Arn complexes (n=1-14) are recorded in the vicinity of the O-H stretch vibrations (1 , 3 ) by means of photodissociation spectroscopy in a tandem mass spectrometer. Rotational and vibrational anal ysis of the dimer spectrum clearly shows that the first Ar ligand forms a linear ionic hydrogen bond to the H2 O+ cation. Complexation transforms the symmetric (antisymmetric) O-H stretch of H2 O+ into bound and free O-H oscillators in the H2 O+ -Ar dimer. Strong coupling between the bound O-H stretch (1 ) and the intermolecular bond leads to a large red shift in the 1 frequency and a short lifetime. In contrast, the free O-H stretch (3 ) is only little affected upon Ar compl exation, and the resulting long lifetime allows for the resolution of the rotational structure (including spin-rotation). The second Ar ligand binds to the second proton of the water cation (C2v ). Complexation with further Ar ligands cause smaller fr equency shifts owing to weaker intermolecular bonds. Ab initio calculations show good agreement with the experimental data.

RC07

15 min

10:27

INFRARED SPECTRA OF NH3 + -Arn (n=1-6) COMPLEXES (n=1-6) OTTO DOPFER, NICOLA SOLCA, and ROUSLAN V. OLKHOV, Institut f¨ur Physikalische Chemie, Universit¨at Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland. Intermolecular forces and microsolvation processes in NH3 + -Arn complexes (n=1-6) are studied by infrared photodissociation spectroscopy in a tandem mass spectrometer. Analysis of the rovibrational structure yields a proton bound dimer equilibrium structure with C2v symmetry. Observed tunnelling splittings are attributed to hindered internal rotation of the planar NH3 + cation within the dimer. Systematic frequency shifts observed in the spectra of larger clusters provide a detailed pict ure of the cluster growth. The first three Ar ligands form equivalent linear proton bonds, leading to highly symmetric cluster structures with C2v or D3h symmetry. The next two Ar atoms bind to the 2pz orbital of the central N atom on opposit e sites of the C3 axis, leading to structures with C3v and D3h symmetry. Ab initio calculations support the interpretation of the experimental data.

RC08

15 min

10:44

THE ROTATIONAL SPECTRA OF THE HCCCNH+ , NCCNH+ , AND CH3 CNH+ IONS C. A. GOTTLIEB, A. J. APPONI, M. C. McCARTHY, and P. THADDEUS, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 and Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138; H. LINNARTZ, Institute for Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH 4056 Basel, Switzerland. The rotational spectra of the HCCCNH+ , NCCNH+ , and CH3 CNH+ ions have been observed for the first time in a supersonic molecular beam by Fourier transform microwave (FTM) spectroscopy. Precise values of the rotational and centrifugal distortion constants were determined for all three ions, and quadrupole hyperfine structure was observed in HCCCNH+ and NCCNH+ . It was found that eQq for the inner nitrogen atom in HCCCNH+ and NCCNH+ is an order of magnitude smaller than that of the terminal nitrogen atom in most polyatomic molecules of this size. The narrow-line FTM spectra reveal that the ions move with essentially the same velocity as the neutral buffer gas in the supersonic beam; there is no evidence for excess broadening of the rotational lines of the ions with respect to those of the neutrals. The abundances of the ions here are sufficiently high to be detectable by present laser techniques.

198

RC09

15 min

11:01

MILLIMETER-WAVE TIME-RESOLVED STUDIES OF HCO+ - H2 INELASTIC COLLISIONS LEE C. OESTERLING, ERIC HERBST, and FRANK C. DE LUCIA, Department of Physics, The Ohio State University, 174 W. 18th Ave., Columbus, OH 43210. Rotationally inelastic cross sections for HCO+ - H2 collisions at 77 K and 41 K were measured using time-resolved double resonance spectroscopy. The J = 2 level of HCO+ was pumped with a gated KVARZ millimeter-wave synthesizer 2 transition was probed with a klystron based synthesizer. From an analysis of the time dependent and the J = 3 millimeter-wave absorption of the probe, rotationally inelastic cross sections were calculated. Since the reactions which form HCO+ are highly exothermic, HCO+ is not formed in thermal equilibrium. With the ionizing electron beam on, the average rotational and translational temperatures are greater than the temperature of the background gas. These average temperatures are a function of the initial temperature at which the ions are formed, the rate at which the ions are thermalized, and the rate at which the ions are destroyed. We will discuss how we are able to determine the average translational and rotational temperatures of the molecular ions using millimeter-wave time-resolved spectroscopy. RC10 PURE ROTATIONAL SPECTRUM OF TiC` IN THE GROUND ELECTRONIC STATE

15 min

11:18

ATSUKO. MAEDA, Institute for Astrophysics and Planetary Sciences, Ibaraki University, Mito, Japan 3108512; TSUYOSHI HIRAO, PETER F. BERNATH, Centre of Molecular Beam and Laser Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada; and TAKAYOSHI AMANO, Institute for Astrophysics and Planetary Sciences, Ibaraki University, Mito, Japan 310-8512. Electronic spectra of TiC` have been studied for years by various spectroscopic methods. However, it is still not clear whether the ground state of TiC` is 4 r which is assumed to be the case by the analogy of TiH and the results of ab initio calculations. In this study, we have detected pure rotational spectra of TiC` for four spin components by using a submillimeter-wave spectrometer with a combination of frequency and discharge modulations at Ibaraki University. TiC` is generated in a DC glow discharge of a gas mixture of TiC`4 ( 1 mTorr) and Ar buffer( 80 mTorr). Discharge current is 40 mA, and mainly the 440 GHz region is surveyed. We have obtained effective spectroscopic constants for all the spincomponents for v = 0 that are consistent with the previous FT results. Our analysis will provide very accurate structural information on the ground electronic state of this radical. RC11 Post-deadline Abstract FIRST EXPERIMENTAL OBSERVATIONS WITH CROSSED BEAMS FOR THE Sc + NO AND AB INITIO POTENTIAL ENERGY SURFACES

10 min 11:35 !ScO + N REACTION

G.-H. JEUNG, P. LUC, R. VETTER, Laboratoire Aim´e Cotton (NCRS UPR3321), Bˆat. 505, Campus d’Orsay, 91405 Orsay, France; D. W. KIM, K. S. KIM, Department of Chemistry, Pohang University of Science and Technology, Pohang 790-784, South Korea; H. S. LEE and Y. S. LEE, Department of Chemistry, Korea Advanced Institute of Science and Technology Taejon 305-701, South Korea.

199

RC12 Post-deadline Abstract 10 min 11:47 FIRST EXPERIMENTAL OBSERVATIONS WITH CROSSED BEAMS FOR THE Ti + NO ! TiO + N AND Ti + O2 ! TiO + N REACTIONS AND AB INITIO POTENTIAL ENERGY SURFACES G.-H. JEUNG, P. LUC, R. VETTER, Laboratoire Aim´e Cotton (NCRS UPR3321), Bˆat. 505, Campus d’Orsay, 91405 Orsay, France; C. NAULIN, M. COSTES, Laboratoire de Physico-Chimie Mol´eculaire (CNRS UMR5803), Universit´e Bordeau I, 33405 Talence, France; K. H. KIM, Y. S. LEE, Department of Chemistry, Korea Advanced Institute of Science and Technology Taejon 305-701, South Korea; J. H. MOON, Y. H. KIM, Department of Ceramics, Korea Institute of Science and Technology, 130-650 Seoul, South Korea.

200

RD. VIBRONIC INTERACTIONS THURSDAY, JUNE 15, 2000 – 8:30 AM Room: 1015 McPHERSON LAB Chair: JON HOUGEN, NIST, Gaithersburg, MD

RD01 Invited Talk EXPERIMENTAL MANIFESTATIONS OF THE JAHN-TELLER EFFECT

30 min

8:30

TIMOTHY A. BARCKHOLTZ, JILA, University of Colorado, Boulder, CO 80309-0440. Molecules in orbitally degenerate states are subject to a number of effects that typical molecules are not. One such effect is Jahn-Teller coupling, which is the coupling between the vibrational and electronic angular momenta. This talk will review how Jahn-Teller coupling is manifested in the spectroscopy of molecules in degenerate electronic states. Both the vibronic and rovibronic structure of these states will be covered, with particular emphasis on the additional complications that occur when spin-orbit coupling is significant. The electronic spectra of the methoxy radicals (CH3 O, CH3 S, CF3 O, and CF3 S) and of the Cp radical (C5 H5 ) will be used to illustrate how the Jahn-Teller effect can be observed experimentally. Lastly, it will be shown how recently developed ab initio methods can be used to aid in the interpretation of the experimental spectra of Jahn-Teller molecules.

RD02 15 min 9:05 CAS-SCF COMPUTATIONS ON JAHN-TELLER, RENNER-TELLER AND SECOND ORDER JAHN-TELLER SYSTEMS MICHAEL ROBB, MICHAEL J. BEARPARK, LUIS BLANCAFORT, Department of Chemistry, King’s College London, Strand, London WC2R 2LS, UK. The information that can be obtained from ab initio CAS-SCF computations on Jahn-Teller, Renner-Teller and second order Jahn-Teller systems will be presented in order to stimulate discussion of how this information can be used to rationalize experimental data. Several examples will be presented for each potential surface topology. The D5h Jahn-Teller crossing and associated C2v minima and saddle points were optimised for the cyclopentadienyl radical at the CASSCF / cc-pVDZ level of theory. The C2v structures were characterised by computing analytic force constants. Zero point energies calculated for all C5 H4 D and C5 HD4 isomers of the C2v minima suggest an alternative interpretation of the experimentally observed degeneracy resolution. For the benzene radical cation, the Jahn-Teller topology has also been mapped out. Finally, the use of symmetry in characterising the second order Jahn-Teller effect will also be discussed for D2h pentalene and D8h cyclooctatetraene.

201

RD03 15 min 9:22 AB INITIO CALCULATION OF THE SPECTROSCOPICALLY OBSERVABLE JAHN-TELLER CONSTANTS OF THE Xe 2 E001 STATE IN THE CYCLOPENTADIENYL RADICAL BRIAN E. APPLEGATE AND TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210; TIMOTHY A. BARCKHOLTZ, JILA, National Institute of Standards and Technology and The Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309. Recently developed methodsa for calculating Jahn-Teller coupling constants using commercially available ab initio programs have made it possible to attack some long standing problems in understanding molecules exhibiting Jahn-Teller e 2 E00 effects in multiple vibrational modes. One of these problems has been the analysis of the vibronic structure in the X 1 state of the cyclopentadienyl radical, C5 H5 . This radical nominally possesses D5h symmetry; however, upon distortion the symmetry is reduced to C2v . In accordance with this a CASSCF/6-31G* calculation with the 5  electrons in the 5  orbitals as the active space finds the compressed dienylic geometry as the global minimum on the potential energy surface, while only an insignificant 4 cm 1 barrier is predicted for internal rotation to the elongated allylic geometry. A conical intersection calculation on the electronic states that correspond to these two geometries indeed recovers the symmetric D5h geometry. Using these calculations, as well as a generalized restricted Hartree-Fock calculation to generate normal modes and frequencies we are able to describe the nature of this distortion in terms of four normal modes of vibration. Only the three modes lowest in energy make significant contributions to the distortion and as such have significant linear Jahn-Teller coupling constants. The calculated value of the Jahn-Teller coupling constants and unperturbed vibrational frequencies are extremely useful for the analysis of the laser excited, dispersed fluorescence spectra of the cyclopentadienyl radical. a Barckholtz

T. A.; Miller T. A., J. Phys. Chem., 1999, 103, 2321.

RD04

15 min

9:39

e 2 E00 STATE IN THE CYCLOPENTADIJAHN-TELLER ANALYSIS OF THE VIBRONIC STRUCTURE OF THE X 1 ENYL RADICAL

BRIAN E. APPLEGATE, ANDREW J. BEZANT, AND TERRY A. MILLER, The Ohio State University, Dept. of Chemistry, Laser Spectroscopy Facility, 120 W. 18th Avenue, Columbus, Ohio 43210; TIMOTHY A.BARCKHOLTZ, JILA, National Institute of Standards and Technology and The Department of Chemistry and Biochemistry, University of Colorado Boulder, Colorado 80309. e2 A00 -X e 2 E00 transition have existed for nearly 20 While room temperature wavelength resolved emission spectra of the A 2 1 a years , the vibrational assignment of these spectra has remained elusive. The major difficulty with the vibrational analysis e state. Newly obtained jet-cooled laser is attributable to complications arising from the dynamic Jahn-Teller effect in the X excited wavelength resolved fluorescence emmision spectra, in conjunction with recent b calculations aimed at predicting the relevant Jahn-Teller constants have now made the complete analysis of the available spectral data possible. The transitions involving the Jahn-Teller active vibrations have been analyzed in terms of the three lowest energy harmonic vibrations of the appropriate symmetry (e02 ), assuming only linear Jahn-Teller interactions. Additional features of the spectrum may be described in terms of the fundamentals, overtones, and combination bands of the non-Jahn-Teller active vibrations as well as combinations involving the Jahn-Teller active modes. a Nelson

H. H.; Pasternack L.; McDonald J. R., Chem. Phys, 1983, 74, 227. B. E.; Barckholtz T. A.;Miller T. A., to be published

b Applegate

Intermission

202

RD05 JAHN-TELLER AND PSEUDO JAHN-TELLER INTERACTIONS IN METAL TRIMERS

15 min

10:15

WOLFGANG E. ERNST, Departments of Physics and Chemistry, Penn State University, 104 Davey Laboratory, University Park, PA 16802. Over the last 15 years, a number of metal trimers have been studied spectroscopically. Because of their high symmetry, they possess many doubly degenerate electronic states that underlie Jahn-Teller or pseudo Jahn-Teller interactions or both. Most trimer spectra were recorded at vibrational resolution and the analyses relied on vibronic level patterns to agree with a standard description of linear and quadratic Jahn-Teller coupling. High resolution spectroscopy including a rotational analysis has only been applied to alkali trimers so far. Many more details about the coupling between electronic and nuclear motion could be obtained and Jahn-Teller and pseudo Jahn-Teller effects could unambiguously been distinguished. The current state of our understanding of these vibronic interactions in metal trimers will be reviewed in this talk. Moreover, the most recent results involving the influence of anharmonicity of the potential on the pseudorotational barrier will be discussed.

RD06 15 min 10:32 TENSORIAL DEVELOPMENT FOR THE ROVIBRONIC HAMILTONIAN AND TRANSITION MOMENTS OF OCTAHEDRAL XY6 MOLECULES IN A FOURFOLD DEGENERATE ELECTRONIC STATE ¨ V. BOUDON, M. REY, M. LOETE, F. MICHELOT, Laboratoire de Physique de l’Universit´e de Bourgogne, UMR CNRS 5027, 9 Av. A. Savary, BP 4780, F-21078 DIJON Cedex, FRANCE. Some transition-metal hexafluorides like ReF6 , OsF6 or IrF6 have the particularity to posses a incomplete electronic subshell leading to low-lying degenerate electronic states. The ground electronic state is generally also degenerate. This implies the existence of very complex rovibronic couplings and thus the observation of unsual spectraa ; b A few years ago, we have elaborated a tensorial formalism adapted to octahedral molecules with an odd number of electronsc (i.e. with half-integer angular momenta), defining the OhS group as the octahedron point group with its spinorial representations. We also presented a systematic tensorial development in the SU (2) CI  OhS group chain for the vibronic Hamiltonian of an octahedral molecule in a fourfold degenerate electronic stated of symmetry G0g . However, this development had the disadvantage to lead to infinite matrices, due to the particular form of the vibronic coupling terms (Jahn-Teller, . . . ). Moreover, the molecular rotation was not included. In this talk, we present a systematic tensorial development of the full effective rovibronic Hamiltonian for a given vibronic polyad in a G0g electronic state. A construction of the form X He = et ((E ( e ) V ( v ) )( ) R( ) )(A1g ) i

i

is proposed, where we define electronic operators E ( e ) . This Hamiltonian has now finite matrices in the basis of the considered polyad. A similar construction is also given for the transition moment operators (dipole moment and polarizability) which are necessary to calculate transition intensities. a R.

S. McDowell and L. B. Asprey J. Mol. Spectrosc. 45, 491–493 (1973). Boudon, M. Rotger and D. Avignant J. Mol. Spectrosc. 175, 327–339 (1996). c V. Boudon, and F. Michelot J. Mol. Spectrosc. 165, 554–579 (1994). d V. Boudon, F. Michelot, and J. Moret-Bailly J. Mol. Spectrosc. 166, 449–470 (1994). b V.

203

RD07 QUASI-JAHN-TELLER EFFECT IN CHEMICAL REACTIONS

15 min

10:49

LICHANG WANG , Department of Chemistry, The Ohio State University, Columbus, OH 43210. It will be demonstrated that the quasi-Jahn-Teller effect in chemical reactions is a nuclear quantum effect, T q , induced by electronic nonadiabaticitya . Further, T q is equivalent to the Diagonal Born-Oppenheimer Correction. Results including and without T q for a model system will be presentedb . The research shows clearly that one has to consider this effect in order to obtain various quantities within a spectroscopic accuracy for systems where this effect is no longer negligible. a L. b L.

Wang, Chem. Phys. Lett. (a) 285 (1998) 359; (b) submitted. Wang, Chem. Phys. 237 (1998) 305.

RD08

15 min 11:06 2 RENNER-TELLER EFFECTS IN THE i GROUND STATES OF THE SiCH/SiCD and GeCH/GeCD RADICALS HAIYANG LI, TONY C. SMITH, DAVID A. HOSTUTLER, DENNIS J. CLOUTHIER, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; ANTHONY J. MERER, Chemistry Department, University of British Columbia, 2036 Main Mall, Vancouver, BC, Canada V6T 1Z1. ˜ 2 i systems of ˜ 2 + - X Extensive emission spectra have been obtained by laser excitation of selected bands of the A jet-cooled SiCH, SiCD, GeCH and GeCD. Up to four quanta of the Si-C or Ge-C stretching mode and even quanta of the bending mode have been observed by pumping upper state  vibronic levels. Pumping vibronically induced transitions to upper state  vibronic levels has given further information about odd quanta of the bending mode. The assignments have been fitted using a vibronic coupling matrix that includes spin-orbit coupling, Renner-Teller effects, Fermi resonances, and the interaction between nearly degenerate bending levels of different 2 and K. The emission spectra of SiCH and SiCD, with A  ! , are easily assigned and the Fermi resonance interaction between 22 and 3 is found to be small. In the germanium species, the spin-orbit coupling is much larger than ! and the spectra are more complicated. Levels of different 2 with
2 = 1 are mixed by a
P = 0, HRT HSO cross-term of substantial magnitude, disrupting the energy level pattern. Results from the vibronic analyses of all four species will be presented.

204

RE. MICROWAVE THURSDAY, JUNE 15, 2000 – 1:30 PM Room: 1153 SMITH LAB Chair: HELEN LEUNG, Mount Holyoke College, South Hadley, MA

RE01 15 min THE ROTATIONAL SPECTRA AND STRUCTURES OF TWO ISOMERS OF THE HCCH-OCS DIMER

1:30

SEAN A. PEEBLES and ROBERT L. KUCZKOWSKI, Department of Chemistry, University of Michigan, 930 North University Ave., Ann Arbor, MI 48109-1055 USA. Two isomers of the HCCH-OCS dimer have been characterized by pulsed supersonic nozzle, Fourier-transform microwave spectroscopy. The more stable isomer has the acetylene and OCS molecules aligned almost parallel, while the higher energy form is T-shaped, with the S atom of the OCS interacting with the triple bond of the acetylene. The experimentally determined structures will be compared to results obtained from a semi-empirical modeling program and ab initio calculations.

RE02 15 min THE ROTATIONAL SPECTRA AND STRUCTURES OF THE HCCH-(OCS)2 and OCS-(HCCH)2 TRIMERS

1:47

SEAN A. PEEBLES and ROBERT L. KUCZKOWSKI, Department of Chemistry, University of Michigan, 930 North University Ave., Ann Arbor, MI 48109-1055 USA. The two mixed trimers HCCH-(OCS)2 and OCS-(HCCH)2 have been identified and assigned by FTMW spectroscopy. Rotational constants and dipole moment components for both species are consistent with triangular, barrel-shaped configurations of the monomers. The assignment of the rotational spectra of eight isotopomers for HCCH-(OCS)2 enabled an unambiguous structure determination and the discovery that this trimer contains a polar OCS dimer fragment. The two OCS molecules are found to be aligned in an unusual parallel arrangement with their dipole moments reinforcing one another. Four isotopomers of the OCS-(HCCH)2 trimer were assigned. Due to a lack of isotopic data, a full structure determination was not possible. Semi-empirical calculations did, however, give a structure that aligned the acetylene monomers in a geometry intermediate between T-shaped and parallel that was consistent with the experimental data.

205

RE03 15 min 2:04 ISOMERS IN HELIUM COMPLEXES: OBSERVATION OF T-SHAPED AND LINEAR He-CH3 F, AND PREDICTION OF TWO NEARLY ISOENERGETIC FORMS OF He-ClF3 KELLY J. HIGGINS, and WILLIAM KLEMPERER, Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138. The existence of multiple minima on the intermolecular potential energy surface of rare gas-molecule complexes appears quite general. Localization of the rare gas atom in the various potential energy minima results in several ”isomeric” forms of a single complex. The combination of ab initio calculations and microwave/millimeter wave spectroscopy of heliummolecule complexes has proven quite valuable in the study of this phenomena. As presented previously,a the ab initio intermolecular potential of He-CH3 F exhibits two main wells: -46.9 cm 1 in the ”linear” position at the C end of the C-F axis, and -44.8 cm 1 in the ”T-shaped” position on the side of the C-F axis. Bound state calculations place the ground state in the T-shaped position with a state localized in the linear position being 4.0 cm 1 higher in energy. Pure rotational transitions of states localized in each minima, as well as transitions between the states, have now been observed experimentally. The initial observation of the linear state depended upon strong mixing of the JKa Kc = 220 level of the ground state with the JK = 20 level of the linear state. This mixing is accurately predicted by the ab initio potential and serves as a sensitive probe of the intermolecular potential. The observed T-shaped to linear gap is 4.4 cm 1 . The intermolecular potential of He-ClF3 at the MP2 level was previously presented.b While qualitatively correct, significant quantitative differences existed between the MP2 surface and selected points calculated at the MP4 level. We report a much refined full MP4 surface and bound state calculations. Two primary minima exist: -53.9 cm 1 in the linear position at the Cl end of the C2v axis, and -59.9 cm 1 in the T-shaped position above the molecular plane. Bound state calculations place the ground state in the linear minima, with a T-shaped state less than 1 GHz higher in energy. It is interesting to note that in both He-ClF3 and He-CH3 F the ground state is localized in the shallower of the two potential minima. a 54th b 52nd

International Symposium on Molecular Spectroscopy (1999) International Symposium on Molecular Spectroscopy (1997)

RE04 15 min 2:21 MICROWAVE INVESTIGATIONS OF C5 H5 N-SO3 AND HCCCN-SO3 : THE PRINCIPLE OF HARD AND SOFT ACIDS AND BASES APPLIED TO PARTIALLY BONDED SYSTEMS S. W. HUNT, D. L. FIACCO, M. CRADDOCK, and K. R. LEOPOLD , Department of Chemistry, University of Minnesota, Minneapolis, MN 55455. The Lewis acid-base adducts C5 H5 N-SO3 and HCCCN-SO3 have been studied by Fourier transform microwave spec˚ and free rotation of the SO3 troscopy. The spectrum of C5 H5 N-SO3 indicates a short N-S bond length of 1.91540(66) A ˚ only slightly less than unit. In contrast, HCCCN-SO3 is more weakly bound with an N-S distance of 2.5676(76) A, the expected van der Waals interaction distance. The NSO angles are 98.9212(45)o and 91.89(36)o for C5 H5 N-SO3 and HCCCN-SO3 respectively. A Townes and Dailey analysis of the 14 N quadrupole coupling constant of C5 H5 N-SO3 indicates a transfer of 0.54 electrons upon formation of the dative bond. This is a physical measurement of the ”soft” portion of the chemical interaction and comparisons are made with other adducts of SO3 . Bonding is considered in light of Pearson’s concept of Hard and Soft Acids and Bases, a noting the correlation of adduct properties, such as electron transfer and bond length, with the energy gap between the donor and acceptor orbital. a R.

G. Pearson J. Am. Chem. Soc. 85, 3533 (1963).

206

RE05 MICROWAVE ROTATIONAL SPECTRUM OF THE Kr-CH4 VAN DER WAALS COMPLEX

15 min

2:38

¨ YAQIAN LIU and WOLFGANG JAGER, Department of Chemistry, University of Alberta, Edmonton, AB, Canada, T6G 2G2. The first pure rotational spectra of a rare gas-methane van der Waals complex, namely Kr-CH4 , were recorded, using a pulsed molecular beam Fourier transform microwave spectrometer. Five isotopomers, including 86 Kr-CH4 , 84 Kr-CH4 , 83 Kr-CH , 82 Kr-CH , and 80 Kr-CH , were studied. Two sets of transitions were measured in the range of 4-18 GHz: one 4 4 4 with K =0, J =0 to J =4, the other with K =1, J =1 to J =4. These transitions were assigned to occur within the A, K =0 and F , K =1 states, respectively. Of the latter set, two transitions of the 84 Kr and 86 Kr containing isotopomers were first measured at NIST.a Rotational constants and centrifugal distortion constants were fitted separately for both states. The determined rotational constants agree well with the values determined in the previous IR study by Pak et al :,b with a difference of less than one MHz for the A, K =0 state, and a somewhat larger difference of 24 MHz for the F , K =1 state. This larger difference might indicate a misassignment in the IR region for the F , K =1 state. The search for the E -state transitions is still ongoing. a I. b I.

Pak and R. Suenram, private communication. Pak, D. A. Roth, M. Hepp, G. Winnewisser, D. Scouteris, B. J. Howard, and K. M. T. Yamada, Z : Naturforsch : 53a, 725 (1998).

RE06 15 min THE MICROWAVE SPECTRA OF THE FLUOROBENZENE-KRYPTON VAN DER WAALS COMPLEX ¨ KAI BRENDEL and HEINRICH MADER, Institut f¨ur Physikalische Chemie, Olshausenstr. 40, D-24098 Kiel, Germany.

2:55

Universita¨ t Kiel,

The microwave spectra of the Kr-fluorobenzene van der Waals complex have been recorded in the frequency region 1-15 GHz, using pulsed molecular beam Fourier transform microwave spectrometers employing either a cylindrical cavity driven in the H01 -mode (1-6 GHz) or a confocal Fabry-Perot resonator (6-20 GHz). The spectra of four isotopomers, involving 82 Kr, 83 Kr ,84 Kr and 86 Kr, were observed in natural abundance. The spectra analyses yielded rotational and centrifugal distortion constants. Structural data were derived from the rotational ˚ above the ring plane. For the 83 Kr containing complex, constants and the Krypton atom was found to be located 3.65 A the nuclear quadrupole coupling hyperfine structures were resolved and analyzed.

RE07 10 min 3:12 A COMPLETE STRUCTURE FOR THE GAUCHE ROTAMER OF 1,1,2,2-TETRAFLUOROETHANE FROM MICROWAVE SPECTROSCOPY ´ MATE, ´ ANNORMAN C. CRAIG, Department of Chemistry, Oberlin College, Oberlin, OH 44074; BEL EN GELA HIGHT WALKER, and RICHARD D. SUENRAM, Optical Technology Division, National Institute of Standards and Technology, Gaithersburg, MD 20899. The complete molecular structure of the high-energy, gauche rotamer of 1,1,2,2-tetrafluoroethane, Freon F134, has been determined using Fourier transform microwave spectroscopy. A total of five different 13 C- and 2 H-substituted isotopomers and the normal species have been studied. Unlike the nonpolar anti rotamer, the gauche form has a permanent electric dipole moment, which permits a direct rotational analysis. The electric dipole moment was also determined using the Stark effect of two low-J transitions. The resulting dipole moment is c = 8.186(7) x 10 30 C.m [2.454(2) Debye]. Two recent ab initio calculations, one using the hybrid Hartree-Fock, density functional method (ACM)a and the other an MP2/6-31G modelb , are in reasonable agreement with experimental findings. a M. Muir and J. Baker, J. Mol. Phys. 89, 211 (1996). b S. Papasavva, K.H. Illinger, and J.E. Kenny, J. Phys. Chem. 100, 10100, (1996).

207

RE08 15 min 3:24 PSEUDO-re STRUCTURES FROM EXPERIMENTAL ROTATIONAL CONSTANTS AND AB INIT IO VIBRATION-ROTATION CONSTANTS P. GRONER, and R. D. WARREN, Department of Chemistry, University of Missouri - Kansas City, Kansas City, MO 64110. The determination of accurate molecular structures from spectroscopic data has been and remains a formidable challenge. Inspired by the close agreement of experimental and theoretical centrifugal distortion constants and inertial defects a , we explored the possibility of using vibration-rotation constants from ab initio calculations together with experimental ground state constants to derive approximate re structures. In the past, this has been done successfully for (very) small molecules with large basis sets at high levels of calculation (for an example, see b ). We were interested in finding out whether MP2 calculations with small basis sets yield sufficiently accurate vibration-rotation constants for larger molecules. This method was tested with MP2/6-31G(d) calculations for the COCl2 , HCOCl, FCOCl, and HCOOH, for which near equilibrium structures derived from experimental data are available in the literature. It was subsequently used to reevaluate the structures of CF2 NH, CFe NCl, CH3 OCOCl, CH3 OCOCN, and two conformers of CH3 CH2 PH2 . Many, but not all, problems encountered in deriving meaningful structures are significantly reduced. It appears that the structures are  c and r (1) /r (2) d structures. comparable to rm m m a P. Groner, J. R. Durig, D. D. DesMarteau, and S.-H. Hwang, J. Chem. Phys. 110, 9411 (1999). P. Groner, J. R. Durig, and D. D. DesMarteau, J. Chem. Phys. 105, 7263 (1996). b M. Oswald, J. Fl¨ ugge, and P. Botschwina, J. Mol. Struct. 320, 227 (1994). c M. D. Harmony, in: J. R. Durig (Ed.), Vibrational Spectra and Structure, (Elsevier, Amsterdam, 2000) Vol. 24. d J. K. G. Watson, A. Roytburg, and W. Ulrich, J. Mol. Spectrosc. 196, 102 (199).

Intermission RE09 15 min 4:00 PHYSICAL INTERPRETATION OF TORSION-ROTATIONAL PARAMETERS IN METHANOL AND ITS ISOTOPOMERS: COMPARISON OF GLOBAL FIT AND CENTRIFUGAL CALCULATION RESULTS YUN-BO DUAN and ANNE B. MCCOY, Department of Chemistry, The Ohio State University, Columbus, OH 43210. The molecular parameters for 12 C and 13 C methanol and its isotopomers CH3 OH, CH3 OD, and CD3 OD with O-16, 17 and 18 will be presented. Two methods have been used to determine the parameters. One uses the recent formulation of the centrifugal distortion effects in terms of the potential parameters for a molecule that contains a three-fold symmetric internal rotora b . The other uses through a global fit to observed high resolution microwave, millimeter wave and Fourier transform far-infrared spectra based on a reduced torsion-rotational Hamiltonian modelc d e . The calculated parameters, in particular the constants that represent interactions between torsion and rotation, are used to interpret the relationships among the terms in the reduced Hamiltonian. By calculating the molecular parameters from several potential energy functions for methanol isotopomers we can check the quality of these potentials. Finally, the calculated parameters are compared with the parameters that were obtained from global fits. The good agreement between the calculated centrifugal distortion terms and those derived from the fits to the spectra demonstrates that the derived formulae provide a useful tool for understanding the physical origins and mass dependence of fundamental molecular parametersf g . a Y.

B. Duan and K. Takagi, Phys. Lett. A 207, 203 (1995). B. Duan, L. Wang, X. T. Wu, I. Mukhopadhyay, and K. Takagi, J. Chem. Phys. 111, 2385-2391 (1999). c Y. B. Duan, L. Wang, I. Mukhopadhyay, and K. Takagi, J. Chem. Phys. 110, 927-935 (1999). d Y. B. Duan, L. Wang, and K. Takagi, J. Mol. Spectrosc. 193, 418-433 (1999). e Y. B. Duan and A. B. McCoy, J. Mol. Spectrosc., 199, 302-306 (2000). f Y. B. Duan, A. B. McCoy, L. Wang, and K. Takagi, J. Chem. Phys. 112, 212-219 (2000). g Y. B. Duan, A. B. McCoy, L. Wang, and K. Takagi, J. Chem. Phys., (2000), submitted b Y.

208

RE10 10 min 4:17 CALCULATION OF MOLECULAR PARAMETERS FOR ISOTOPOMERS OF CD3 OH SPECIES OF METHANOL LI WANG, AND KOJIRO TAKAGI, Department of Physics, Toyama University, Toyama 930-8555, Japan. Tortion-rotational constants have been determined for 12 C and 13 C isotopomers of the CD3 OH species of methanol with O-16, 17 and 18, using the calculation procedure based on the centrifugal distortion theory for a molecule containing a three-fold symmetric internal rotor.a These parameters have also been obtained by fitting to obseved microwave linesb for 12 CD16 OH in which a correction-free reduced Hamiltonianc has been used. It is shown that all of the calculated constants 3 are in better agreement with the fitting ones for this molecule than those for the other species of methanol. a Y. B. Duan and K. Takagi, Phys. Lett. A 207, 203 (1995). b M. S. Walsh, Li-Hong Xu, and R. M. Lees, J. Mol. Spectrosc. 188, 85 (1998); A. Predoi-Cross, Li-Hong Xu, M. S. Walsh,

R. M. Lees, M. Winnerwisser, and H. Lichau, J. Mol. Spectrosc. 188, 94 (1998).

c Y. B. Duan, L. Wang, I. Mukhopadhyay, and K. Takagi, J. Chem. Phys. 110, 929 (1999).

RE11 THE GROUND STATE ROTATIONAL SPECTRUM OF CH2 DOH

15 min

4:29

J. C. PEARSON, B. J. DROUIN AND H. M. PICKETT, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109. The rotational spectrum of CH2 DOH has been the subject of a number of investigations into the asymmetric-top asymmetric-frame internal rotation problem. This work is the first complete investigation of the ground state spectrum and the first opportunity to address the asymmetric internal rotation problem in detail. The ground state spectrum is composed of three sub states e0 , e1 and o1 of the CS group. Transitions of a- and b-types are observed within each torsional sub state. Transition between each sub state are allowed with e to e transitions following a- and b-type selection rules and e to o transitions following c-type selection rules. Over 1000 transitions of all types have been observed and assigned in the spectrum to J>20 and K=5 between 4 to 600 GHz. The assignments of a significant number of the transitions have been confirmed with combination differences. An analysis of the data set, using an IAM type model based on the structure, fits the observed data to an accuracy of several times the experimental uncertainty. The model and a discussion of the asymmetric-top asymmetric-frame internal rotation problem will be given along with the derived constants.

209

RE12 THE ROTATIONAL SPECTRUM OF DEUTERATED ISOPROPANOL (CH3 )2 CHOD

15 min

4:46

EIZI HIROTA, The Graduate University for Advanced Studies, Hayama, Kanagawa 240-0193, JAPAN ; YOSHIYUKI KAWASHIMA, Department of Applied Chemistry, Kanagawa Institute of Technology, Atsugi, Kanagawa 243-0292, JAPAN. Isopropanol has already been investigated by microwave spectroscopy and has been confirmed to exist in both trans and gauche; the two equivalent gauche forms were found split by tunneling by 46 798.50 MHz.a The observation was extended to the deuterated species that has a deuterium in the hydroxyl group, and the trans spectra were detected. However, the gauche spectra have eluded assignment, presumably because the tunneling splitting was comparable with the rotational energy, making the rotational spectrum complicated. In the present study we have employed a Fourier transform microwave spectrometer and have succeeded in unambiguously assign the gauche spectra, because the low temperature simplified the spectrum and because the deuterium nuclear quadrupole coupling effect resulted in hyperfine structure only for the spectra 000 , 111 000 , of the deuterated species. In an initial stage, we observed two lines for each of the four transitions: 110 202 111 , and 212 101 with the splitting ranging from 8.5 MHz to 36.0 MHz. By carefully examining all the possible assignments of the two lines to the symmetric and antisymmetric states, we finally arrived at the tunneling splitting of about 4400 MHz, which was much larger than that previously estimated (about 2000 MHz). We then extended the assignment to other transitions of J up to 5, including some between the symmetric and antisymmetric rotational levels. As in the case of the parent species, these inter-state transitions were stronger than those within the symmetric or antisymmetric state. The main molecular parameters we obtained from the analysis are symmetric state: A = 8198.9104 (19), B = 7998.3213 (14), C = 4611.6717 (15), zz = -0.1051 (57), xx - yy = -0.0437 (27); antisymmetric state: A = 8199.4366 (17), B = 7998.0368 (20), C = 4611.6876 (20), zz = -0.0987 (54), xx - yy = -0.0444 (27); symmetric/antisymmetric cross terms: Rzx = 180.330 (13), Rxy = 271.2791 (60), zx = -0.030 (30), xy = -0.143 (39),
E = 4431.4581 (27) in MHz with the standard deviations in parentheses. a E.

Hirota, J. Phys. Chem. 83, 1457 (1979)

RE13 15 min 5:03 THE ROTATIONAL/CONCERTED TORSIONAL SPECTRUM OF THE g’Gg-CONFORMER OF ETHYLENE GLYCOL DINES CHRISTEN, Institute of Physical and Theoretical Chemistry, University of T¨ubingen, Germany; LAURENT COUDERT, Laboratoire de Photophysique Mol´eculaire, CNRS, Universit´e de Paris-Sud, France; RICK D. SUENRAM and A. HIGHT WALKER, Molecular Physics Division, NIST, Gaithersburg, MD, USA; A. LARSON and DIETER CREMER, Teoretisk Kemi, G¨oteborg, Sweden. The microwave spectrum of the energetically unfavoured g’Gg-conformer of ethylene glycol is reported. This spectrum is dominated by an interconversion geared-type large amplitude motion during which each OH-group in turn forms the intramolecular hydrogen bond. The microwave spectrum has been analyzed using a Watson-type Hamiltonian plus a 1.4 GHz tunneling splitting. The rotational dependence of this tunneling splitting was examined using an IAM approach yielding quantitative information on the tunneling path between configurations. Unexpectedly, but in agreement with the ab initio calculations, both OH-groups are rotated through 240Æ in going from one equilibrium configuration to the other one, passing on the way through the g’Ga-conformations.

210

RE14 THE SUBMILLIMETER-WAVE SPECTRUM OF ALLYL ALCOHOL (CH2 =CHCH2 OH)

10 min

5:20

BRIAN J. DROUIN, JOHN C. PEARSON, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099. Two isomers of allyl alcohol have been further studied in selected regions of the submillimeter and microwave spectra. The skew-gauche and syn-gauche conformations have been previously identified at room temperaturea ; b and in a free-jetc , respectively. The present study positively identifies the syn-gauche conformer in the gas-phase at room temperature and confirms that tunneling, as opposed to internal rotation, of the hydroxyl proton is the predominant perturbation up to Ka = 30. Further measurements made in the X-band, at kHz precision, have increased the precision of the Coriolis coupling terms and energy level (tunneling) splitting. Extension of the spectral measurements has provided a set of spectral parameters that can accurately predict spectral line frequencies through much of the sub-millimeter. a A.

N. Murty and R. F. Curl, Jr., J. Chem. Phys. 46, 4176-4180 (1967) Badawi, P. Lorencak, K. W. Hillig II, M. Imachi and R. L. Kuczkowski, J. Mol. Struc. 162, 247-254 (1987). c S. Melandri, P. G. Favero and W. Caminati, Chem. Phys. Let. 223, 541-545, (1994)

b H.

RE15 15 min 5:32 THE ROTATIONAL-TORSIONAL SPECTRUM OF METHYL FORMATE:PRECISE MEASUREMENTS ON AND INTERPRETATION OF MILLIMETRIC WAVE TRANSITIONS H.NADGARAN, Physics Department, Shiraz University, Shiraz 71454, Iran.. By using a cavity spectrometer with a helium-cooled detector and computerised methods of background removal, we have measured a total of 43 new lines of the ground torsional state of methyl formate with precision of 0.1 MHz. These include b-type transitio ns of high J and K quantum numbers. When combined with other literature reported data collected by conventional waveguide spectrometers [Plummer et al. 1984-1986], they are fitted to single-state Hamiltonians of internal axis method (IAM) in which the C-C bond is considered as one of the three mutually perpendicular axes of the molecular reference frame. In these Hamiltonians, we have allowed rotational parameters to differ between A and E torsional states because of coupling to other vibrations of corres ponding symmetry [Oka et al. 1967]. As these interactions are symmetry dependent, it is not surprising that one obtains better fits by permitting different average parameters for the two species [Maes et al. 1987, Plummer et al. 1984]. The frequencies of the data were up to 355 GHz and 505 GHz for E and A species respectively. Rms deviations of 0.43 MHz for A and 0.27 MHz for E symmetry states were obtained. A total of 14 floating parameters and 3 fixed parameters were used in the fit. This very satisfact ory results of the fit can be highly useful in precise prediction of line frequencies in other bands. The author would like to thank the council of research of Shiraz university for supporting this work. References Plummer,G.M., Herbst,E., Delucia,F.C., Blake,G.A., Ap.J.Suppl.,55,633,1984. Plummer,G.M., Herbst, E.,Delucia,F.C., Blake,G.a., Ap.J.Suppl.,60,949,1986. Blake,G.A., Sutton,E.C., Masson,C., Phillips,T.G., Ap.J.Suppl., 60, 357,1986. Oka,T., J. Chem. Phys., 47,12,1967. Maes,H., Wlodarczak,G., Banchert,D., Demaison,J.Z., Natureforch., 429, 97, 1987.

211

RF. METAL CLUSTERS THURSDAY, JUNE 15, 2000 – 1:30 PM Room: 1009 SMITH LAB Chair: MICHAEL DUNCAN, University of Georgia, Athens, GA RF01 Invited Talk ELECTRONIC SPECTROSCOPY OF ALUMINUM ATOM-MOLECULE COMPLEXES

30 min

1:30

PAUL J. DAGDIGIAN, Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218. A review of recent work in our laboratory on the spectroscopy and dynamics of weakly bound complexes of aluminum atoms with various molecules will be presented. These complexes are prepared in a pulsed supersonic beam and probed with laser fluorescence excitation spectroscopy. Unlike Al-rare gas complexes, the atom-molecule complexes undergo predissociation. Resonance fluorescence is thus not detected, and the excitation spectra are observed by monitoring emission from lower atomic levels, or from electronically excited products formed by reaction within the complex. Spectra of several electronic transitions within the Al-M complexes, for M = H2 , D2 , N2 , CH4 , CD4 , will be presented and interpreted. The spectra are dominated by excited-state progressions in the van der Waals stretch vibrational mode. Estimates of Al-M binding energies for the various electronic states will be presented. In some cases, the Lorentzian linewidth is sufficiently small that partial rotational resolution was achieved. In particular, differences between the rotational structure of Al-H2 and Al-N2 , which have T-shaped and linear equilibrium geometry, respectively, in the ground electronic state, will be discussed. RF02 ZEKE-PFI SPECTROSCOPY OF THE Al-(H2 O) AND Al-(D2 O) COMPLEXES.

15 min

2:05

J.K. AGREITER, A.M. KNIGHT, G.A. GRIEVES, M.A. DUNCAN, Department of Chemistry, University of Georgia, Athens, GA 30602, USA. The weakly bound complexes Al-(H2 O) and Al-(D2 O) are prepared with pulsed laser vaporization and studied with singlephoton ZEKE-PFI spectroscopy. The spectra consist of progressions in the Al-water stretch in the ground state of the corresponding cations (Al-(H2 O): !e+ =327:5 cm 1 ). The origin energy, Al atom ionization potential and the known Al+ -(H2 O) bond energy produce a neutral Al-(H2 O) bond energy of D0 = 1440 cm 1 . Partially resolved rotational structure suggests that the cation complexes have C2v structures, while the neutrals are non-planar. The neutral structure and energetics are consistent with a metal-water coordinate-covalent bond, which has been predicted by theory. RF03 EXPERIMENTAL AND THEORETICAL STUDY OF THE BOUND-FREE G2 (4p)

15 min 2:22 2 X (3p) TRANSITION OF

AlAr JAMES M. SPOTTS, CHI-KIN WONG, MATTHEW S. JOHNSON, MITCHIO OKUMURA, A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125; JEFFREY I. SHEEHY and PETER. W. LANGHOFF, Air Force Research Laboratory, OLAC PL/RKS, Edwards Air Force Base, CA 93524. The G2 (4p) state of AlAr has been observed by both 1+1 and 2+1 resonant multiphoton ionization from the X2 (3p) state. The G state is a dissociative state resulting in a broad but asymmetric band peaked at 33920 cm 1 , detectable by action spectroscopy upon one- and two-photon absorption. The atomic Al 3p-4p transition is forbidden, and molecular AlAr transitions between states arising from these states are primarily two-photon in character due to the weak mixing of Al-atom configurations. Simulations of both the one- and two-photon bands using ab initio potential curves and dipole moment functions calculated by MR-CI methods are in good agreement with observations.

212

RF04

10 min

2:39

PHOTODISSOCIATION SPECTROSCOPY OF THE Ca+ -Ar2 COMPLEX J. E. REDDIC, J. VELASQUEZ, K. N. KIRSCHNER, M. A. DUNCAN, Department of Chemistry, University of Georgia, Athens, GA 30602, USA. The weakly bound complex Ca+ -Ar2 produced by laser ablation in a pulsed nozzle cluster is studied with mass-selected resonance enhanced photodissociation spectroscopy. A short doublet progression.(!e0 = 82.07 cm 1 ) to the blue of the 2D 2 S atomic transition is assigned to the D2  X 2 + system. Spin-orbit splitting (A = 19.67 cm 1 ) of the r X 2 + system. No systems doublets suggests a linear geometry. A peak observed at 13956 cm 1 is assigned the C2 r 2 2 S in this complex. Additionally, complexes with more than two are detected from the derived atomic transition P rare-gas ligands were probed and showed no sharp structure. Mller-Plesset second-order perturbation theory was used to ˚ and a dissociation energy (De ) for atomization of 4.864 kcal/mol determine the Ca+ -Ar2 bond distances (re ) of 3.064 A (Ca+ -Ar2 ! Ca+ + 2Ar ). This calculation included the correlation of the valence and core electron using a generated basis set for calcium and the aug-ccVQZ basis set for the argon atoms, resulting in a total of 271 basis functions for the calculations.

Intermission RF05 OPTICAL STARK SPECTROSCOPY OF YTTRIUM DICARBIDE,YCC

15 min

3:10

ALEXANDRA JANCZYK and TIMOTHY C. STEIMLE, Department of Chemistry and Biochemistry, Arizona State University, Tempe, Az, 85287-1604. Yttrium dicarbide is the only gas-phase metal dicarbide to be detected via an opyical spectroscopic technique1 . Here we report on our preliminary analysis of the optical Stark spectrum of the YCC. Numerous branch features in the K0 =1 K00 =0 sub-band of the 310 A2 A1 -X2 A1 transition near 13225 cm 1 were recorded in the presence of a variable static electric field. A near linear tuning of the spectral features is observed indicating a near degeneracy of the asymmetry componets of the excited state.The linear tuning was modeled to give  =1.5656 D for the (0,0,1)vibrational level of the A2 A1 state. 1 T.C.Steimle,A.J.Marr,J.Xin,A.J.Merer,K.Athanassenas and D.Gillett,J.Chem. Phys.106,2060(1997).

RF06

15 min

˜ 2 (0; 0; 0) OPTICAL STARK MEASUREMENT FOR THE A

3:27

X2 + (0,0,0) OF MgNC

ROBERT R. BOUSQUET and TIMOTHY C. STEIMLE, Department of Chemistry and Biochemistry, Arizona State University, Tempe, Az, 85287-1604. ˜ 2 3=2 (0; 0; 0) X2 + (0,0,0) The high resolution laser induced fluorescence spectrum of MgNC was recorded for the A 3=2 ˜ 2 1=2 (0; 0; 0) X2 + (0,0,0) band systems and optical Stark measurements were performed on the Q R12 (0:5) and the A 1=2 and P Q12 (0:5) branch features. The field free spectrum of this band system was first measured by Wright and Millera . The MgNC radicals were produced by the laser ablation of a magnesium rod in the presence of a acetonitrile/argon supersonic expansion. The permanent electric dipole moment, , for 24 MgNC was determined to be 3.116(36)D and 3.424(103)D for ˜ 2 1=2 (0,0,0) and X2 + (0,0,0) states, respectively. The analysis of the Stark measurements will be reported and a the A 1=2 comparison of the permanent dipole moments of MgNC and CaNCb will be given. a. Wright, R. R. and Miller, T. A., J. Mol. Spec. 194, 219, (1999). b. Scurlock, C.T., Fletcher, D.A. and Steimle, T. C., J. Chem. Phys. 101, 7255, (1994).

213

RF07 LASER INDUCED FLUORESCENCE SPECTROSCOPY OF JET-COOLED MgOH

15 min

3:44

MASARU FUKUSHIMA and TAKASHI ISHIWATA, Department of Information Sciences, Hiroshima City University, Asa-Minami, Hiroshima 731-3194, Japan.

~ 2 + transition of MgOH under the We have measured the laser induced fluorescence (LIF) spectrum of the A~2  X supersonic free expansion condition. The radicals were generated in the Ar jets using the usual laser ablation technique. The observed spectrum consists of five vibronic bands. Rotationally resolved LIF excitation spectra of these five bands have been recorded. Three bands clearly show a 2  2  rotational structure, typical of a linear molecule, and are assigned ~ 2 + (000 0), n = 0, 2, and 4, vibronic bandsa . It is reported that the A~ state is bent structureb . to the A~2 (0n1 0) X The observed rotational structure suggests a very low value of < 125 cm 1 for A~ state barrier of the bending potential. The other two vibronic bands exist between the (021 0) (000 0) and (041 0) (000 0) bands, and precise analysis of these bands is now underway. No vibronic bands are observed in the energy region above the (041 0) (000 0) vibronic band: a manifestation of a predissociation for this energy region. Very recent theoretical resultsc predict the dissociation process from the A~ state to Mg(1 S) + OH(2 ) to possess a barrier of about 1700 - 1800 cm 1 from the bottom of the A~ state. M. F. acknowledge correspondence with David O. Harris and Ian P. Hamilton. a

1 : the Mg OH stretching, 2 : the Mg O H bending, and 3 : the O H stretching vibrational modes.

b Y.

Ni, Ph. D. Thesis, University of California, Santa Barbara (1986). Theodorakopoulos, Ioannis D. Petsalakis, and Ian P. Hamilton, J. Chem. Phys. 111, 10484 (1999).

c Giannoula

RF08 RESONANT TWO PHOTON MPI SPECTROSCOPY OF Ca2 Cl3

15 min

4:01

J. D. LOBO, A. DEEV, C. K. WONG, M. OKUMURA, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125. The electronic spectra of Ca2 Cl3 and its isotopomers formed by laser ablation were observed by R2MPI at 650 nm. This salt cluster can have several possible structures, including a CaCl
CaCl2 adduct and a degenerate D3h structure exhibiting both Jahn-Teller and pseudo-Jahn-Teller distortions. Irregularities in the spectra suggest the presence of extensive nonadiabatic vibronic coupling. Results will be compared to predictions based on ab initio and pseudo-potential calculations.

RF09 15 min 4:18 DIMERS OF ALKALINE EARTH METAL HALIDE RADICALS, (MX)2 (M = Be, Mg, Ca; X = F, Cl): A THEORETICAL STUDY G.P. LI and I.P. HAMILTON, Department of Chemistry, Wilfrid Laurier University, Waterloo, Canada N2L 3C5. Alkaline earth metal halide radicals, MX, di-halides, MX2 , and halide radical dimers, (MX)2 (M = Be, Mg, Ca and X = F, Cl), are studied using density functional theory, MP2 and CCSD(T) methods. The ground states of MX2 are all singlet 1  + with D g 1h symmetry except that of CaF2 which is 1 A1 with C2v symmetry. The ground states of (MX)2 are all 1 singlet Ag with D2h symmetry except that of (CaF)2 which is 3 A1 with C2v (distorted D2h ) symmetry. Stabilities of the halide radical dimers have been examined versus some reactions, such as (MX) 2 ! 2M + 2X, (MX)2 ! M2 + X2 , (MX)2 ! 2MX and (MX)2 ! MX2 + M. Several transition states of these reactions have been established at the MP2/6-311+G* level. The calculated results for the halide radicals and di-halides are in good agreement with experimental values. The calculated results for the halide radical dimers can serve as a guide for spectroscopic studies of these species.

214

RF10 THE VIBRATIONAL SPECTRA OF TRANSITION METAL MONOCARBONYLS MOLECULES

15 min

4:35

B. TREMBLAY, L. MANCERON, and M.E. ALIKHANI, L.A.D.I.R./Spectrochimie Moleculaire, U.M.R. 7075, CNRS-Universite Pierre et Marie Curie, Boite 49, 4 Place Jussieu, 75252 Paris, Cedex 05, France. The infrared spectrum of MCO molecules (M=Co, Ni, Pd, Pt, and Cu) isolated in solid argon has been reinvestigated. Various isotopic data (12 C/13 C, 16 O/18 O, natural isotopes for the metal) on 1 , 2 , 3 and number of two quantum transitions have been measured in the near- and far-infrared regions. This enables a complete harmonic force-field calculation based on calculated geometry can be estimated. Comparisons of spectroscopic parameters for the Ni-, Pd-, PtCO and Co-, Ni-, CuCO series, experimental binding energies and the latest ab initio predictions are also presented. The bond force constants can be compared and the results show that the pertubations of the CO ligand are very unreliable indicators of the evolution of the binding energies, contrary to the metal-carbon force constant.

215

RG. INFRARED THURSDAY, JUNE 15, 2000 – 1:30 PM Room: 1000 McPHERSON LAB Chair: NASSER MOAZZEN-AHMADI, University of Calgary, Calgary, Canada

RG01 15 min RITZ ASSIGNMENT AND AWAT ANALYSIS OF THE RING-PUCKERING HOT BANDS OF OXETANE

1:30

GIOVANNI MORUZZI, Dipartimento di Fisica dell’Universit`a di Pisa and INFM, Via Filippo Buonarroti 2, I-56127 Pisa, Italy; MARC KUNZMANN, Institut f¨ur Physikalische Chemie der Georg-August-Universita¨ t G¨ottingen, Germany; BRENDA P. WINNEWISSER AND MANFRED WINNEWISSER, PhysikalischChemisches Institut, Justus-Liebig-Universit¨at, Heinrich-Buff-Ring 58, D-35392 Gießen, Germany. The oxetane molecule consists of 10 atoms, corresponding to 24 vibrational degrees of freedom. These include one largeamplitude vibration, i.e., the ring puckering, with its fundamental at approximately 53 cm 1 . The first rotationally resolved spectrum of these transitions has been reported recently. We have investigated the oxetane spectrum between 52 and 162 cm 1 . Six different
vrp = 1 rotation-puckering transitions are observed in this region. Preliminary analyses of the lowest three bands have already been presentedabc . In the present contribution we complete our assignment work in the investigated spectral region. We shall present the results of fitting our FIR assignments and previously published MW and MMW data with the AWAT1 program (Watson Hamiltonian for an asymmetric rotor, A-reduction, programmed by K. M. T. Yamada), and with an equivalent program now incorporated into the Ritz program, for levels up to vrp = 5. Watsonian frequency predictions have been used as a feed-back for the assignments in the most dense and entangled spectral regions. An analysis of the dependence of the rotational constants and of the quartic centrifugal distortion constants of the Watsonian on the puckering state will also be attempted. a M. Winnewisser, M. Kunzmann and M. Lock, 53rd Ohio State University International Symposium on Molecular Spectroscopy, Columbus, June 15–19, 1998, TD04 b G. Moruzzi, M. Kunzmann, B. P. Winnewisser and M. Winnewisser, 15th International Conference on High Resolution Molecular Spectroscopy, Prague, Czech Republic, August 30 – September 3, 1998, H7 c G. Moruzzi, M. Kunzmann, B. P. Winnewisser and M. Winnewisser, 16th International Colloquium on High Resolution Molecular Spectroscopy, Dijon, France, September 6–10, 1999, F20

216

RG02 15 min 1:47 ANALYSIS OF THE ROTATIONAL STRUCTURE IN TWO BANDS OF THE ANTI ROTAMERS OF 1,1,2,2TETRAFLUOROETHANE AND ITS d2 ISOTOPOMER IN HIGH-RESOLUTION INFRARED SPECTRA NORMAN C. CRAIG, CATHERINE M. OERTEL and DAVID C. OERTEL, Department of Chemistry, Oberlin College, Oberlin, OH 44074; MICHAEL LOCK, Physikalisch-Chemisches Institut, Justus Liebig Universit¨at, D-35392 Giessen, Germany. Structures of the rotamers of 1,1,2,2-tetrafluoroethane are of interest as part of the study of the gauche effect, in which rotamers of fluorocarbons exhibit surprising energy relationships. The structure of the polar gauche rotamer has been determined in cooperation with the microwave group at NIST. The structure of the nonpolar anti rotamer can be found by analysis of the rotational structure in high-resolution (0.0018 cm 1 ) infrared spectra of the gas phase at 100Æ C. Analyzing this structure is challenging for this rather heavy molecule which is also a very asymmetric top ( = -0.30). For the parent molecule, a good start had been made at NIST and PNL on the analysis of the spectrum of an A/C-type band observed by a jet-cooled-beam, diode-laser technique.a We have greatly extended the analysis of this band with the new spectrum and have also analyzed the rotational structure of a B-type band. In the spectrum of the d2 species, we have completed the analysis of the rotational structure of the B-type band and the A-type component of the A/C-type band. The analysis of the B-type bands for both isotopomers includes assignments of oblate series for small K c values. Rotational constants for the anti rotamer of both isotopomers will be reported. a Stone,

S. C.; Philips, L. A.; Fraser, G. T.; Lovas, F. J.; Xu, L. -H.; Sharpe, S. W. J. Mol. Spectrosc. 1998, 192, 75.

RG03 15 min 2:04 VIBRATIONAL POTENTIAL ENERGY SURFACES FOR THE RING-PUCKERING AND RING-FLAPPING VIBRATIONS OF 1,3-BENZODIOXOLE IN ITS S0 AND S1 ( ,   ) ELECTRONIC STATES J. LAANE, K. MORRIS, S. SAKURAI, E. BONDOC, Department of Chemistry, Texas A&M University, College Station, TX 77842-3012; N. MEINANDER, Department of Physics, University of Helsinki, Helsinki, Finland.

217

RG04 10 min 2:21 CONFORMATIONAL STABILITY FROM TEMPERATURE DEPENDENT FT-IR SPECTRA OF LIQUID RARE GAS SOLUTIONS AND AB INITIO CALCULATIONS FOR 1-PENTYNE BARRY R. DREW AND J. R. DURIG, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499. Variable temperature studies of the infrared spectra (3500 to 400 cm 1 ) of 1-pentyne, CH3 CH2 CH2 CCH, dissolved in liquid xenon (-55 to -100Æ C) and liquid krypton (-105 to -150Æ C) have been recorded. These data indicate that both the anti (methyl group trans to the acetylenic group) and gauche conformers are present in the fluid states. Utilizing seven sets of conformer pairs for the xenon solution and ten sets of conformer pairs for the krypton solution, the enthalpy has been determined to be 506 cm 1 (0.600.07 kJ/mol) and 454 cm 1 (0.540.05 kJ/mol), respectively, with the anti conformer the more stable form. Optimized geometries and conformational stabilities were obtained from ab initio MP2/631G(d), MP2/6-311+G(d,p), MP2/6-311+G(2d,2p) and MP2/6-311+G(2df,2pd) calculations with all of the calculations predicting the gauche rotamer to be the more stable form. The ro adjusted structural parameters have been obtained from a combination of the microwave rotational constants and ab initio predicted parameters.

RG05 CONTINUING RESEARCH INTO THE OVERTONE SPECTRA OF TRIMETHYL AMINE

15 min

2:33

BRANT BILLINGHURST, KATHLEEN GOUGH, Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada; HENRIK G. KJAERGAARD AND GEOFF LOW, Department of Chemistry, University of Otago, Dunedin, New Zealand. The CH bonds in trimethylamine that lie trans to the nitrogen lone pair are known to be much longer than the gauche CH. This is the most extreme known example of the trans lone pair effect, depicted by frontier molecular orbital theory as a delocalization of the lone pair electrons into the anti-bonding orbitals of the trans CH bonds. The spectrum of trimethylamine has been the subject of much study over the years, ranging from the fundamental infra-red of trimethyl amine and selectively deuterated derivatives to the overtone spectra of trimethylamine. We have collected the overtone spectra ( 1st 5th ) of some deuterated derivatives in order to improve the assignment of the overtone peaks. A harmonically coupled anharmonic oscillator local mode mathematical model has been used to predict the intensity of the absorbtions in the overtone regions.

Intermission

218

RG06 LARGE TORSIONAL EFFECTS IN THE PARALLEL BAND (v5

15 min

=1

3:15

0) OF CH3 SiF3

S. -X. WANG, Department of Physics and Astronomy, University of British Columbia, Vancouver, B. C., Canada, V6T 1Z1; J. SCHRODERUS, Department of Physical Sciences, University of Oulu, P.O. Box 3000, Oulu, Finland, FIN 90401 ; I. OZIER , Department of Physics and Astronomy, University of British Columbia, Vancouver, B. C., Canada, V6T 1Z1; and V.-M. HORNEMAN, Department of Physical Sciences, University of Oulu, P.O. Box 3000, Oulu, Finland, FIN 90401. The lowest frequency parallel fundamental band 5 of CH3 SiF3 near 388 cm 1 has been measured at a resolution of 0:00125 cm 1 with Fourier transform spectroscopy. Internal rotation plays a surprisingly important role in determining the form of the spectrum. The C3v -type parallel band normally expected for a near-spherical top was strongly distorted by the Fermi-like interactions between the torsional stack of levels (v6 = 0; 1; 2::) in the ground vibrational state and the corresponding stack with (v5 = 1). The torsional fine structure in the spectrum was increased from  0:0008 to  1:1 cm 1 due to resonant interaction between (v5 = 0; v6 = 4) and (v5 = 1; v6 = 0) states. A detailed analysis was carried out of a data set consisting of 1194 infrared frequencies determined in the current work along with 134 mw, mmw and molecular beam measurements previously reported for the two torsional states v6 = 0 and 1 of the ground vibrational state. A fit has been obtained to within experimental accuracy for all the data blocks using a vibration-torsionrotation Hamiltonian with 31 parameters, including 3 parameters that characterize the Fermi-like interactions. The standard deviation for the infrared data is  0:00016 cm 1 . The Fermi-like terms in the Hamiltonian have two important general implications. First, the coefficients that characterize the Fourier expansion of the torsional barrier in the ground vibrational state undergo significant changes, which can be explained in terms of the contact transformation commonly used to remove intervibrational interactions. This is relevant when the torsional barrier height of CH3 SiF3 is predicted with quantum chemical calculations. Second, due to the strong mixing with the (v5 = 0, v6 = 4) state, the probability density as a function of the torsional angle for the (v5 = 1, v6 = 0) state shows dramatic changes from that predicted with the classical model. This severe mixing with large j
v6 j has serious implications for vibration-rotation relaxation in molecules with low frequency, highly anharmonic vibrational modes.

RG07 10 min 3:32 RAMAN AND INFRARED SPECTRA, CONFORMATIONAL STABILITY, AB INITIO CALCULATIONS AND VIBRATIONAL ASSIGNMENTS FOR ETHYL FLUOROSILANE GAMIL A. GUIRGIS, YASSER E. NASHED, JING TAO AND JAMES R. DURIG, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499. The infrared (3500 to 30 cm 1 ) spectra of gaseous and solid and the Raman (3500 to 10 cm 1 ) spectra of the liquid with quantitative depolarization ratios and solid ethyl fluorosilane, FSiH2 CH2 CH3 , have been recorded. These data indicate that two conformers are present in the fluid states but only one conformer is present in the annealed crystalline state. The mid-infrared spectra of the sample dissolved in liquefied xenon as a function of temperature (-100 to -55Æ C) have been recorded. Utilizing conformer pairs at 1022 (gauche), 1010 (trans), 719 (gauche), 727 (trans), and 693 (trans) cm 1 the enthalpy difference has been determined to be 10118 cm 1 (1.210.22 kJ/mol) with the gauche conformer the more stable species and the one remaining in the solid. The optimized geometries, conformational stabilities, harmonic force fields, infrared intensities, Raman activities, depolarization ratios, and vibrational frequencies will be reported for both conformers from MP2/6-31G* ab initio calculations. The gauche conformer is predicted to be the more stable rotamer from ab initio calculations in agreement with the experimental results.

219

RG08 15 min 3:44 RAMAN AND INFRARED SPECTRA, CONFORMATIONAL STABILITY, BARRIERS TO INTERNAL ROTATION, AB INITIO CALCULATIONS AND ro STRUCTURE FOR VINYL SILYL FLUORIDE YASSER NASHED, GAMIL A. GUIRGIS, M. A. QTAITAT AND J. R. DURIG, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499. The Raman (3250 to 10 cm 1 ) and infrared (3250 to 40 cm 1 ) spectra of the gaseous and solid vinyl silyl fluoride (CH2 CHSiH2 F), have been recorded. From the far infrared spectrum of the gas, the fundamental asymmetric torsions for both the cis and gauche conformers have been observed at 102.34 and 86.56 cm 1 , respectively, with each having several excited state transitions falling to lower frequencies. From these transitions, the potential function to internal rotation has been determined with the following values: V1 , V2 , V3 , V4 and V6 , with the gauche conformer thermodynamically preferred by 8220 cm 1 . The cis to gauche, gauche to gauche, and gauche to cis barriers are 702 (8.40 kJ/mol), 588 (7.04 kJ/mol) and 620 cm 1 (7.42 kJ/mol), respectively. Variable temperature (-105 to -150Æ C) studies of the infrared spectra of the sample dissolved in liquid krypton have been carried out. From these data, the enthalpy difference has been determined to be 76 cm 1 (0.91 kJ/mol). Additionally, ab initio calculations have been carried out utilizing the 6-31G(d) basis sets to obtain the conformational stability, barriers to internal rotation and optimized structural parameters.

RG09 10 min 4:01 CONFORMATIONAL ANALYSIS, BARRIERS TO INTERNAL ROTATION AND AB INITIO CALCULATIONS OF 3-FLUORO-1-BUTENE SEUNG WON HUR, TODOR K. GOUNEV, GAMIL A. GUIRGIS AND JAMES R. DURIG, Department of Chemistry, University of Missouri-Kansas City, Kansas City, MO 64110-2499. The far infrared spectrum of gaseous 3-fluoro-1-butene has been recorded at a resolution of 0.10 cm 1 . The asymmetric torsional fundamental of the most stable HE (hydrogen atom eclipses the double bond) and the higher energy FE (fluorine atom eclipses the double bond) conformations have been observed at 88.7 and 105.9 cm 1 , respectively, each with excited states falling to lower frequencies. From these data, the asymmetric torsional potential function governing internal rotation about the C-C bond has been determined. The potential coefficients are: V1 = -21211, V2 = 38112, V3 = 5766, V1 0 = 32217, V2 0 = -21410 and V3 0 = -24013 cm 1 . From variable temperature (-55 to -100Æ C) measurements of the infrared spectra of xenon solutions, the enthalpy difference between the HE and FE conformers has been determined to be 876 cm 1 (25017 cal/mol). The same determination yields an enthalpy difference of 2925 cm 1 (83515 cal/mol) between the HE and the least stable ME (methyl group eclipses the double bond) conformer. The vibrational data have been compared to the corresponding quantities obtained from ab initio calculations employing the MP2/6-31G(d) basis set.

220

RG10 15 min 4:13 VIBRATIONAL DEPENDENCE OF THE TORSIONAL BARRIER HEIGHT AND THE A/B INTENSITY EVOLUTION IN THE OH OVERTONE SPECTRA OF METHANOL M. ABBOUTI TEMSAMANI, LI-HONG XU, Department of Physical Sciences, University of New Brunswick, N.B. Canada E2L 4L5; D. S. PERRY, Department of Chemistry, University of Akron, Ohio 443253610. Rizzo and co-workersa have used supersonic-jet infrared-laser-assisted photofragment spectroscopy (IRLAPS) to record the O-H stretching overtone spectra of CH3 OH. Their analysis of the rotation-torsion structures revealed the following interesting features: (i) the torsional A-E splitting decreases monotonically as OH increases, indicating increase of the torsional barrier height V3 , (ii) a-type transitions become dominant at higher excitations of the OH stretching vibration, (iii) a 1:1 anharmonic resonance occurs between the OH stretch and CH stretch vibrations, reaching its maximum in the 51 region. The third observation has been recently studied by Quack and Willekeb for the case of CD2 HOH, by means of ab initio fivedimensional potential energy and dipole moment surfaces. The present contribution explores possible ab initio explanations for the first two observations. At the MP2 level with 6-311G+(3df,2p) basis set, effective one-dimensional functions for the potential energy, dipole moment (a and b directions), barrier height and torsional constant F have been obtained by scanning the O-H bond length in order to take into account the mechanical and electrical anharmonicities. All ab initio quantities have been expressed as Taylor expansions in the dimensionless coordinate, q . Calculations have been carried out in the harmonic basis set to yield vibrational energies and eigenfunctions. The latter have been used to compute the patterns of the barrier height V3 , the torsional constant F , and the evolution of the infrared intensity ratio Ia /Ib , as functions of the OH vibrational quantum number. All our ab initio results agree with the experimental observations in points (i) and (ii) above. Details of the calculations, the corresponding results and the comparison to experimental data will be presented. a O. b M.

V. Boyarkin, T. R. Rizzo and David S. Perry, J. Chem. Phys. 110, 11359 (1999). Quack and M. Willeke, J. Chem. Phys. 110, 11958 (1999).

RG11 15 min 4:30 FOURIER TRANSFORM SPECTRA AND INVERTED TORSIONAL STRUCTURE FOR A CH3 -BENDING FUNDAMENTAL OF CH3 OH R.M. LEES, LI-HONG XU and ANNA K. KRISTOFFERSON, Department of Physical Sciences, University of New Brunswick, Saint John, NB, Canada E2L 4L5; MICHAEL LOCK and B.P. WINNEWISSER, Physikalisch-Chemisches Institut, Justus Liebig University, D-35392 Giessen, Germany; J.W.C. JOHNS, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, ON, Canada K1A 0R6. The high-resolution Fourier transform spectrum of CH3 OH has been investigated in the 1400-1650 cm 1 region, containing the CH3 -bending fundamental bands. Twenty-two perpendicular
K = +1 subbands have been identified so far, with 1 up to 11 10 for various torsional symmetries. origins ranging from 1490 to 1570 cm 1 for transitions K = 2 Assignment of the subbands to the 4 in-plane (A0 ) or 10 out-of-plane (A00 ) asymmetric methyl-bending modes is not yet clear, but the one subband so far observed with resolved K -doublet structure suggests c-type selection rules consistent with a 10 vibrational assignment. The pattern of the K -reduced torsion-vibration energy  -curves is inverted compared to the normal 1-dimensional picture for n = 0 torsional levels, in agreement with prediction based on fitting torsional variation of ab initio CH3 -bending frequencies to a local mode model. However, the periodicity of the curves is unusual and significantly different from the ground state. The vibrational energy for the bending mode is 1481 cm 1 , and the mean B -value is 0.008 cm 1 higher than that of the vibrational ground state.

221

RG12 15 min 4:47 HIGH RESOLUTION FOURIER TRANSFORM FAR-INFRARED SPECTROSCOPY OF CH3 OD: GLOBAL FIT OF TORSION-ROTATIONAL TRANSITIONS IN THE FIRST THREE TORSIONAL STATES INDRANATH MUKHOPADHYAY, Laser Programme, Centre for Advanced Technology, Indore 452 013, India; XIAN-XIAO HAO, Department of Physics, Yantai Normal University, Yantai, Shandong 264000, China; GEORG CHR. MELLAU and STEFAN KLEE, Physikalisch Chemisches Institut der Justus-LiebigUniversitt, Heinrich-Buff-Ring 58, D-35392 Giessen, Germany; YUN-BO DUAN and ANNE B. MCCOY, Department of Chemistry, The Ohio State University, Columbus, OH 43210. The results of a new analysis of the high resolution Fourier transform far infrared (FIR) absorption spectrum of the torsionrotational band of CH3 OD will be presented. Based on a recently determined set of molecular constants for CH3 ODa we have been able to assign 1126 assigned Fourier transform far-infrared (FIR) transitions that involve the second excited torsional levels with vt = 2. A CH3 OD data set that contains 460 microwave (MW), millimeter wave (MMW) transitions and 3474 Fourier transform FIR transitions with vt  2 and J  21 has been fit using a reduced torsion-rotational Hamiltonian obtained from the one-large-amplitude internal rotation model. The MW and MMW transitions have been fit with a root-mean-square (rms) deviation of 0.12 MHz while FIR transitions have a rms deviation of 0.00026 cm 1 using 61 parameters. These deviations are on the order of the experimental uncertainties, indicating that the MW, MMW and FIR spectral transitions have been fit to the desired accuracy and the reduced torsion-rotational Hamiltonian model is capable of accurately describing CH3 OD energy levels up through the second excited torsional level. The success of the fit demonstrates that the increased general asymmetry in CH3 OD, compared to CH3 OH, can be accounted for adequately by the reduced Hamiltonian model. a Y.

B. Duan and A. B. McCoy, J. Mol. Spectrosc., 199, 302-306 (2000).

RG13 15 min 5:04 ABOUT NATURE OF NONCOINCIDENCE FOR FREQUEHCY AND LINE WIDTH OF STOKES AND ANTISTOKES COMPONENTS IN RAMAN SPECTRA E. N. SHERMATOV, Samarkand State University, Univ. bulv 15, 703004 Samarkand, Uzbekistan. Frequencies and widths (
y1=2 ) of isotropic and anisatropic (1) components of Raman lines was studied. In most cases are y>y and
y1=2 >
y1=2 (11). The study of stoces and antistoces components has been found the noncoincidence of st line freguenc at given temperature, in most cases yast i >yi and
y1=2 (ast)>
y1=2 (st). Obtained results are explained in the context described by us author. Molecules in ground and excited vibration state are in different inner fields. There from natural frequecies of vibration in excited state is larger than those in ground state. This st leads to relations yast i >yi and
y1=2 (ast)>
y1=2 (st). RG14 STRUCTURE OF LIQUIDS AND LOW-FREQUENCY RAMAN EFFECT

15 min

5:21

E. N. SHERMATOV, U.N. RADJABOV, Samarkand State University, Univ. bulv 15, 703004 Samarkand, Uzbekistan. Intensity distribution in line contour of low-frequency Raman effect up to 250 cm 1 from exciting light frequency for stokes and antistokes components in number of organic liqiuds were studied. Contour of line may be present as a central component and two lateral components Obtained results were explained in the context about liquid state structure proposed authors. The maxima lateral components give finds about quantity of spatial by extension. And difference of maxima frequencies for lateral components give finds about value of the change for selforganization extension at oscillations. Line width of central component contains the findings about nonuniform process in media.

222

RH. THEORY THURSDAY, JUNE 15, 2000 – 1:30 PM Room: 1015 McPHERSON LAB Chair: PHILLIP CHRISTIANSEN, Clarkson University, Potsdam, NY

RH01 Invited Talk 30 min 1:30 THE ROLE OF CONICAL INTERSECTIONS IN PHOTOCHEMISTRY,ELECTRONIC ENERGY TRANSFER AND ELECTRON TRANSFER MICHAEL ROBB, MICHAEL J. BEARPARK, FRANCK JOLIBOIS, ADELAIDA SANCHEZ-GALVEZ, PATRICIA HUNT, Department of Chemistry, King’s College London, Strand, London WC2R 2LS, UK; MASSIMO OLIVUCCI, Istituto di Chimica Organica, Universit´a degli Studi di Siena, Via Aldo Moro, I-53100 Siena, Italy; FERNANDO BERNARDI, MARCO GARAVELLI, Dipartimento di Chimica“G. Ciamician”, Universit`a di Bologna, Via Selmi 2, 40126 Bologna, Italy. Theoretical studies show that real surface crossings (conical intersections) are the central feature of most photochemical processes and lie on the reaction path at the point where the excited state reactant or intermediate is delivered to the ground state via a non-adiabatic transition. We will outline how reaction path computations and the use of non-adiabatic trajectories can be used to obtain mechanistic information that can be used to complement modern spectroscopic data. Applications will be presented to the radiationless deactivation of polymethine cyanines and retinal chromophore models and the creation and annihilation of neutral soliton pairs in photoexcited polyene chains. Recently we have begun to study the role of conical intersections in electron transfer processes and excited state energy transfer processes. Applications will be presented for intramolecular electronic energy transfer (IEET) in 9-anthryl-1’naphthyl-alkanes and intramolecular electron transfer (IET): pathways in bis(hydrazine) radical cations.

RH02 ELECTRONIC STATES OF ACTINYL IONS

15 min

2:05

R. M. PITZER, J.-P. BLAUDEAU, S. R. BROZELL, S. MATSIKA, Z. ZHANG, Department of Chemistry, Ohio State University, Columbus, OH 43210. + Actinyl ions, MO2+ 2 , and the corresponding MO2 ions, where M is an actinide metal, are characterized by very strong bonds to the two oxygens. These axial bonds involve the metal  and  orbitals to moderate-to-strong extents, thus raising the corresponding antibonding orbitals to high energy. Thus the low-lying (approximately degenerate) metal orbitals are 5fÆ and 5f. The ground states and low-lying excited states of these ions can be described systematically as weak-field states based on this reduced space of 5f orbitals. Higher excited states are equally well characterized as excitations from the bonding u MO into this space. The general order of strengths of interactions is

axial field > electron repulsion between open-shell electrons > spin-orbit > equatorial field The coupling, although intermediate, is closest to -S, implying the utility of Hund’s Rules.

223

RH03 THE ELECTRONIC SPECTRA OF THE AMERICYL AND CURYL IONS

15 min

2:22

SCOTT R. BROZELL and RUSSELL M. PITZER, Department of Chemistry, The Ohio State University, Columbus, OH 43210. Large graphical unitary group approach (GUGA) spin–orbit multireference configuration interaction (SOCI) singles and doubles calculations have been performed on Am2+ , AmO2 + , CmO2 2+ , and CmO2 + . The ground state of the americyl cation is Æu2 1u 4 3=2u . The first ligand to metal charge transfer (LMCT) state is 3u1 Æu2 2u 6 5=2u . The ground and first 1 2 2 1 7 LMCT states of the isoelectronic dioxoamericium(V) and curyl cations are Æu2 2u 5 + 0+ g and 3u Æu u 3u 0+ g . The dioxocurium(V) cation ground state is Æu2 2u 3u1 6 3=2u . Agreement with experimental LMCT excitation energies is good. f . Recent software developments have enabled the calculation of electric Other intense electronic transitions are f f transitions have been dipole transition moments from GUGA SOCI wavefunctionsa . Tentative assignmentsb of the f reevaluated with the new software. Calculations are planned to search for nonlinear minima of these ions. The actinides are modeled with relativistic effective core potentials and Gaussian correlation consistent double-zeta plus polarization (cc-pVDZ) basis sets. a S. b S.

Matsika and R. M. Pitzer, unpublished, 1999. R. Brozell and R. M. Pitzer, 53rd Ohio State University International Symposium, Paper RB05, p. 207, 1998.

RH04 THE ELECTRONIC STRUCTURE OF THE PLUTONYL ION

15 min

2:39

JEAN-PHILIPPE BLAUDEAU, (Present Address: ASC/MSRC 2435 5th St. B676, Wright-Patterson AFB, Ohio, 45433); BRUCE E. BURSTEN, and RUSSELL M. PITZER, Department of Chemistry, The Ohio State University, Columbus, OH 43210. Restricted Hartree-Fock (RHF) and spin-orbit configuration-interaction (SOCI) calculations were performed on the ground and low-lying excited states of the 1+ plutonyl ion, PuO1+ 2 . These results are compared to previous results on the 2+ . The low energy transitions are f ! f, additionally, ligand-to-metal charge transfer (LMCT) states are plutonyl ion, PuO2+ 2 studied. Recently, intensity spectra are obtainable using these methods. Our results will be compared to experiment.

RH05 SPECIATION OF THE PLUTONYL FORMS OF PLUTONIUM

15 min

2:56

JEAN-PHILIPPE BLAUDEAU, (Present Address: ASC/MSRC 2435 5th St. B676, Wright-Patterson AFB, Ohio, 45433); BRUCE E. BURSTEN, Department of Chemistry, The Ohio State University, Columbus, OH 43210. Plutonium ions in the 5+ and 6+ oxidation states are found in the plutonyl forms, (PuO2 )+ and (PuO2 )2+ , respectively. The speciation of these two complexes was examined using density functional theory (DFT) methods. More specifically, we use the Amsterdam Density Functional (ADF) code, which includes relativistic effects and generalized gradient corrections. The coordination number for the number of water molecules around each of these species, as well as the bond length between the plutonium ion and the water-based oxygen atoms, are determined and compared to experiment - which uses XANES (X-ray Absorption Near-Edge Spectroscopy) and eXAFS (extended X-ray Absorption Fine Structure) spectroscopy. Furthermore, we have examined different geometrical arrangements for the water molecules in these complexes. Optimized structures with real frequencies are obtained and provide us insight into the chemical interactions involved in the solvation of plutonium species.

Intermission

224

RH06 10 min 3:30 THE IONIZATION ENERGY OF THE DIAZOMETHYL (HCNN) AND CYANAMIDYL (HNCN) RADICALS PATRICK E. FLEMING, Department of Chemistry, Santa Clara University, Santa Clara, CA 95053.. The adiabatic ionization energy has been calculated for the diazomethyl radical (HCNN) and the cyanamidyl radical (HNCN) using ab initio methods. The B3LYP density functional method using the 6-311++g(3df,3pd) basis set yields good results for the structures and vibrational frequencies of the radicals. The ionization energy is calculated using complete basis set extrapolation methods for both the radicals and associated cations. The lowest singlet and triplet states have been investigated for the cations. Results for the molecular structures and vibrational frequencies will be presented in addition to the calculated values of the ionization energies.

RH07 15 min 3:42 THEORETICAL PREDICTION OF THE SPECTROSCOPIC CONSTANTS OF FeS: AN AB INITIO MOLECULAR ORBITAL STUDY SACHIKO S. ITONO, YUKARI MITSUI, TETSUYA TAKETSUGU, TSUNEO HIRANO, Department of Chemistry, Faculty of Science, Ochanomizu University, Tokyo 112-8610, Japan; UMPEI NAGASHIMA, National Institute for Advanced Interdisciplinary Research, Ibaraki 305-8562, Japan. Energy levels of nearly degenerated 5
and 5  states have been studied by the MR-SDCI + Q/ Roos-ANO (or various combinations of other basis sets) method with Breit-Pauli Hamiltonian for relativistic effects and spin-orbit coupling interaction corrections. The 5  state has been predicted to be situated between 5
2 and 5
1 substates, and hence the ground state is 5
i . Spectroscopic constants for 5
state (and those for 5  state) are predicted as follows: re = 2.0247 (1.9963) ˚ B0 = 6043.2 (6217.1) MHz; D0 = 3.80 (3.64) kHz;  = 510.4 (543.9) cm 1 ; e = 5.92 (4.88) D. A;

RH08 DFT TEST STUDY ON VAN DER WAALS DIMERS

10 min

3:59

A. J. HERNANDEZ, M. C. SALAZAR, Department of Chemistry, Simon Bolivar University, Caracas 1080A, Venezuela; C. E. MANZANARES, Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76798. Studies in the framework of the supermolecule approach, using density functional theory with basis sets optimized for generalized gradient approximation exchange-correlation calculations, and constructed to give accurate values for nonbonding interactions, will be discussed. Bonding properties of the diatomic van der Waals CO He and N2 He molecules will be presented and compared with recent experimental and theoretical results.

RH09 10 min AB INITIO TEST STUDY ON THE VERTICAL EXCITATION ENERGY OF VAN DER WAALS DIMERS

4:11

M. C. SALAZAR, A. J. HERNANDEZ, Department of Chemistry, Simon Bolivar University, Caracas 1080A, Venezuela; C. E. MANZANARES, Department of Chemistry and Biochemistry, Baylor University, Waco, TX 76798. Studies in the framework of the supermolecule approach using high level ab initio methods of quantum chemistry with different basis sets, constructed to give accurate values for the electric moments and polarizabilities, and supplemented by bond functions placed at the midpoint, will be discussed. Vertical excitation electronic spectra of the diatomic van der Waals CO H2 , CO He and N2 He molecules will be presented and compared with recent experimental results.

225

RH10

15 min

4:23

INTENSITIES OF THE ELECTRONIC SPECTRUM OF NpO+ 2 SPIRIDOULA MATSIKA, RUSSELL M. PITZER, Department of Chemistry, The Ohio State University, 100 W.18th Avenue, Columbus, OH, 43210. The ground and excited states of the linear NpO+ 2 ion have been studied theoretically using relativistic spin-orbit configuration interaction methods based on effective core potentials. Transitions of both the f ! f and charge-transfer types have been calculated. The effect of the equatorial ligands on the intensities of the electronic spectrum of NpO+ 2 is of particular interest. We have surrounded the ion with ligands (water molecules or chloride ions) and calculated the intensities. It has been found that five ligands of either type give an intense peak near 10,000 cm 1 , as observed experimentally. Both our calculations and perturbation theory analysis explain this transition. This study has enabled us to assign several transitions in the experimental spectrum. RH11 STRUCTURE AND SPECTRA OF UO2 F2

15 min

4:40

QI WANG and R.M. PITZER, Department of Chemistry, The Ohio State University, 100 W. 18th Avenue, Columbus, OH, 43210. Uranyl fluoride (UO2 F2 ) is a product of the reaction of UF6 with moisture. There are ca. 200,000 tons of (depleted) UF6 stored in Ohio and ca. 500,000 tons stored in Kentucky. Thus the detection of a luminescent product of leaking UF6 with (humid) air may be useful. Studies of solutions containing UO2 F2n n species have shown that UO2 F2 luminescence is the most intense. Thus we have begun the study of the structure and spectra of UO2 F2 . Initially we were studying the isolated molecule, but we added solvating water molecule (probably 3), and optimized the structure to get the spectra for species in solution. Solvation effects for this neutral molecule are presumably smaller than those for ions. We use relastivistic core potentials to replace the core electrons on all atoms, leaving 50 valence electrons to be treated explicitly. We use basis sets of polarized double-zeta size, as developed in our group. Initial structural studies used DFT (courtesy of D.A. Dixon) to give a (non-planar) C2v structure. MOs are obtained from SCF and MCSCF calculations. The spin-orbit interaction and electron correlation are included using spin-orbit configuration interaction (SO-GUGA in the Columbus programs). Spin-orbit and equatorial-ligand (F , H2 O) interactions compete in determining the splittings of the known (3
g ) luminescent state of the uranyl ion. RH12 FREQUENCY ANALYSIS OF BINARY MIXTURES INVOLVING HYDROGEN BONDS

15 min

4:57

N. SATHYAN, J. SOBHANADRI and V. SANTHANAM, DEPARTMENT OF PHYSICS, PRESIDENCY COLLEGE, CHENNAI - 600 005, INDIA. In molecular dynamics, geometry optimization and energy calculation ignore the constant vibrations of nuclei in molecules. In equilibrium state, there is some regularity in these vibrations and the molecules can be identified from their characteristic spectra. Theoretically calculated vibrational frequencies are used in characterizing molecular potential surfaces. They can be used to determine the nature of a stationary point obtained by geometry optimization. In geometry optimization procedure, the final equilibrium structure will correspond to a minimum on the potential energy surface or it may represent a saddle point. The frequency calculations provide a means of identification for stable but higly reactive short lived molecules by the appearence of a single infrared line. With the help of statistical mechanics, calculated normal mode vibrational frequencies provide information on thermodynamical properties of stable molecules such as reaction entropies and equilibrium isotope effect. Calculated vibrational frequencies are used to correct experimental thermodynamical data at absolute zero and to evaluate zero-point vibrational energies. The true energy of the system is obtained by adding the zero-point energy to the predicted total energy. The polarizability and hyper-polarizability can also be predicted by these frequency calculations.

226

FA. JET AND BEAM FRIDAY, JUNE 16, 2000 – 8:30 AM Room: 1153 SMITH LAB Chair: JOHN HEPBURN, University of Waterloo, Waterloo, Canada FA01 IR-REMPI DOUBLE RESONANCE SPECTROSCOPY OF NO-Ar AND NO-Ne COMPLEXES

15 min

8:30

YANGSOO KIM, J. FLENIKEN, and H. MEYER, Department of Physics and Astronomy, The University of Georgia, Athens, GA 30602; M. H. ALEXANDER, Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742-2021; and P. J. DAGDIGIAN, Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218-2685. Non-resonant two-photon absorption spectroscopy has been applied successfully to the study of high lying electronic states of small molecules and Van der Waals complexes. In this contribution, we present first results of molecular beam experiments in which (2+1) resonance enhanced multiphoton ionization (REMPI) is used to detect the infrared absorption of NO containing complexes. The output of a single mode optical parametric oscillator (OPO) laser excites the first overtone of the NO two-photon chromophore near 2.7m. Resonances are detected either through the depletion of the REMPI signal or through the detection of vibrationally excited complexes. Hot band transitions involving the NO-Rydberg states E 2 , (H 2 , H0 2 ), and F 2
are used to detect infrared absorption bands of the NO-Ar and NO-Ne complexes. For the first time, several bands involving intramolecular bending and stretching motion have been detected as combination bands. Their positions and rotational structures are extremely sensitive to details of the two electronic potential energy surfaces of A0 and A00 symmetry near the minimum. The spectroscopic results for NO-Ar are in excellent agreement with bound state calculations based on an improved ab-initio potential surface by Alexander.a a M.

H. Alexander, J. Chem. Phys. 111, 7426(1999), ibid. 111, 7436(1999).

FA02 HIGH RESOLUTION LIF SPECTROSCOPY OF THE Ar.NO COMPLEX

15 min

8:47

` TIMOTHY G. WRIGHT, JEROME LOZEILLE, School of Chemistry, Physics and Environmental Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, U. K.; CHRISTOPHER C. CARTER and TERRY A. MILLER, Laser Spectroscopy Facility, Department of Chemistry, The Ohio State University, Columbus, OH 43210. ˜ transition in ArNO has been recorded by high-resolution LIF spectroscopy. The work carries on a study ˜ X The A of this complex by REMPI and ZEKE spectroscopya . Spectra have been recorded of the origin region, plus a region to higher energy, that has previously been attributed to stretch and stretch-bend combination bands. Progress in the analysis ˜ state of ArNO is linear (on average) at the of the spectra will be reported; in particular, the previous deduction that the A zero-point, but bent (on average) at higher energies will be examined. a A.

M. Bush, J. M. Dyke, P. Mack, D. M. Smith and T. G. Wright, J. Chem. Phys. 108,406 (1998)

FA03

15 min

9:04

˜ STATE (1 + 1) REMPI SPECTROSCOPY OF NO.N2 and NO.CO VIA THE A ` TIMOTHY G. WRIGHT, SOPHIA E. DAIRE, JEROME LOZEILLE, STUART D. GAMBLIN, School of Chemistry, Physics and Environmental Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, U. K.. ˜ transition of the NO.N2 and NO.CO molecular complexes have been recorded using one-color (1 + 1) REMPI ˜ X The A spectroscopy. The spectra exhibit vibronic features, which indicate some of the underlying rotational structure. Some insights into the structure of the spectra are gleaned from ab initio calculations.

227

FA04 THRESHOLD ION-PAIR PRODUCTION SPECTROSCOPY (TIPPS) of H2 and D2

15 min

9:21

X. K. HU, R. C. SHIELL, Q. J. HU and J. W. HEPBURN, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. Threshold Ion-Pair Production Spectroscopy (TIPPS) can determine field-free energetic thresholds for ion-pair formation a in the same way that pulsed field ionization techniques (ZEKE/MATI) can obtain field-free ionization potentials. H2 and D2 were investigated and their ion-pair thresholds were determined to be 139714.8  1.0 cm 1 and 140370  1.0 cm 1 , respectively. Pulsed field ion-pair formation mostly results from excitation of complex resonances between ion-pairs and electronic Rydberg states of the parent molecule. However, evidence of the direct excitation of ion-pair Rydberg states was also found.

b

a b

J. D. D. Martin and J. W. Hepburn, Phys. Rev. Lett. 79 (1997). J. D. D. Martin and J. W. Hepburn, J. Chem. Phys. 109 (1998).

FA05 15 min 9:38 HS-H BOND DISSOCIATION ENERGY DETERMINATION BY THRESHOLD ION-PAIR PRODUCTION SPECTROSCOPY (TIPPS) X. K. HU, R. C. SHIELL, Q. J. HU and J. W. HEPBURN, Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada. The first single photon threshlod ion-pair production spectrum (TIPPS) of a polyatomic molecule, H2 S, was recorded by monitoring H+ ion generated from the dissociation process H2 S ! HS + H+ . Its ion-pair threshold was determined to be IPP = 122458  3 cm 1 . As a result, the bond dissociation energy (D(HS-H) = 31451  4 cm 1 ) could be calcula ted from D(HS-H) = IPP - IP(H) + EA(HS), by knowing the ionization potential of the hydrogen atom (IP(H) = 109678.772 cm 1 ) and the electron affinity of the HS radical (EA(HS) = 18672  2 cm 1 ).

Intermission FA06 THE REMPI STUDY OF BH IN THE RANGE OF 368-370NM

15 min

10:10

JASON CLARK, EDWARD R. GRANT, Dept. of Chemistry, Purdue University, West Lafayette, IN, USA 47907; LIMIN ZHANG, Open Laboratory of Bond-Selective Chemistry, University of Science and Technology of China , Hefei, Anhui, P.R. China 230026. The mass-selected resonance-enhanced multi-photon ionization (REMPI) of BH in the spectral range of 368-372 nm has been studied. It is shown that the spectral peaks with ion mass 12, 11 and 10 can be assigned to the A1P (v’=2) - X 1S+ (v”=0) one-photon transition of 11BH and 10BH free radicals. With very few REMPI studies on BH, the 2-0 band transitions of A-X for 11BH and 10BH are first observed. By using a 40 K rotational temperature and approximately a 600 K background rotational temperature for BH free radicals, the spectra observed was simulated quite well. The observed isotopic shifts of A1P (v’=2) - X 1S+ (v”=0) band between 11BH and 10BH, which is between 11.7 and 13.0 cm-1, are mainly due to the vibrational isotope shifts.

228

FA07 15 min 10:27 RESONANCE ENHANCED TWO-PHOTON IONIZATION (RE2PI) SPECTRUM OF THE 520 NM SYSTEM OF RbCs YOUNGJEE YOON, YONGHOON LEE, SUN JONG BAEK, JEONGYE CHOI, and BONGSOO KIM, Department of Chemistry, Korea Advanced Institute of Science and Technology, Taejon 305-701, Korea. The rovibrational spectrum of RbCs molecule in the range of 520 nm is observed by the resonance enhanced two-photon ionization (RE2PI) method. A very cold pulsed molecular beam that contains RbCs, Rb2 , Cs2 , etc is generated by a high temperature pulsed nozzle. Only RbCs+ ion could be detected using the time-of-flight (TOF) mass spectrometer (mass resolution  1300). Vibrational bands (v 0 = 6  31) are rotationally resolved by the high resolution dye laser with an intracavity etalon (laser resolution  0:02 cm 1 ). The excited electronic state is assigned to the 5 1 + state that dissociates into Rb(5s 2 S1=2 ) + Cs(7s 2 S1=2 ). By the pseudopotential calculation, the 5 1 + state has adiabatic potential curve with a shelf as a result of the avoided crossing with ionic pair state at long internuclear distances. Observed in the Franck-Condon region, however, the
Gv curve shows ˚. slightly positive curvature for v 0 > 20, which may result from the avoided crossing with the 6 1 + state at  6 A 1 1 By the selection rules of
J = 1 for  !  transitions, only P and R lines are observed. The rotational constants, Bv , and the vibrational term value, Tv , are determined from the analysis of the rotationally resolved spectra. From the vibrational energy level spacing,
Gv , the spectroscopic parameters for the 5 1 + state are determined as Te = 18560:12(8) cm 1 , !e = 40:83(1) cm 1 , and !e xe = 0:2465(6) cm 1 . The dissociation energy, De , is 3811.5 cm 1 . Measured isotope shifts confirm the absolute vibrational numbering. The Be and e obtained from the Bv vs. v plot are 0.013468(8) cm 1 and 7:48(4)  10 5 cm 1 , respectively. Using these molecular constants, potential energy curve of the 5 1 + state is constructed by the RKR method.

FA08 PREDISSOCIATION DYNAMICS OF THE T-SHAPED AND LINEAR ISOMERS OF I2 (B)Ar

15 min

10:44

AMY BURROUGHS and MICHAEL C. HEAVEN, Department of Chemistry, Emory University, Atlanta, GA 30322. Three-dimensional quantum dynamics models for the predissociation of I2 (B)Ar were examined by Gray and Roncero.a Their calculations predicted highly structured rotational population distributions for the I2 (B) products. The distributions were characteristic of dynamics controlled by intramolecular vibrational energy redistribution (IVR). To test this model we have examined final state distributions resulting from predissociation of T-shaped I2 (B)Ar using optical-optical double resonance (OODR) techniques. We observed smooth rotational distributions that are indicative of direct dissociation or IVR occurring with level densities near the statistical limit. OODR measurements were used to probe the highest vibrational level of I2 (B) populated by predissociation of Tshaped I2 (B)Ar. This is a matter of interest as Stevens Miller et al.b have suggested that previous measurementsc may be in error, leading to overestimation of the bond strength for the B and X states of I2 Ar. The previous measurements relied on detection of dispersed fluorescence from I2 (B), and may have been influenced by non-adiabatic decay channels. OODR is a more sensitive technique, potentially capable of detecting the highest energy products prior to non-radiative decay. However, the OODR experiments yield results that are in agreement with the earlier study.c The data do not resolve conflicts associated with the relative bond strengths of the T-shaped and linear isomers.c OODR techniques are being used to characterize the predissociation of linear I2 (B)Ar. Initial measurements show that I2 (B) from the linear isomer has less rotational energy than I2 (B) from the T-shaped complex. Work supported by the National Science Foundation a S.

K. Gray and O. Roncero J. Phys. Chem. 99, 2512 (1995) E. Stevens Miller, C. Chuang, H. C. Fu, K. Higgins and W. Klemperer J. Chem. Phys. 111, 7844 (1999) c J. A. Balzy, B. M. DeKoven, T. D. Russell and D. H. Levy J. Chem. Phys. 72, 2439 (1980)

b A.

229

FA09 ON THE HYPERFINE STRUCTURE OF NO2 LEVELS NEAR DISSOCIATION THRESHOLD

10 min

11:01

JU XIN AND SCOTT A. REID, Department of Chemistry, Marquette University, Milwaukee, WI 53201-1881. We report the application of polarization quantum beat spectroscopy (QBS) to probe the hyperfine structure of single NO2 molecular eigenstates in the region 2.5 cm 1 below dissociation threshold (D0 =25128.57 cm 1 ). The hyperfine interaction is substantially weaker than that found at energies below 22 000 cm 1 , but is similar on average to that observed 50-100 cm 1 below threshold. The ratio of J=3/2 to J=1/2 levels is much larger than that expected on the basis of complete rovibronic mixing, but is consistent with a previous study. FA10 Post-deadline Abstract 15 min 11:13 MILLIMETER WAVE JET SPECTROSCOPY OF CARBON MONOXIDE-CONTAINING VAN DER WAALS COMPLEXES KALEY A. WALKER and A. R. W. MCKELLAR, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada. A new pulsed supersonic jet millimeter wave spectrometer has been constructed at NRC. In similar instruments of this typea ; b , the supersonic jet is injected perpendicular to the millimeter wave radiation. We have found that there is an increase in the sensitivity of our spectrometer by introducing the expansion parallel to the millimeter wave radiation. As a test of this new spectrometer, the pure rotational spectra of KrCO and XeCO. b-type transitions of 5 isotopomers of Kr12 C16 O and 6 isotopomers of Xe12 C16 O have been detected between 75 and 100 GHz, including those of species containing rare gas atoms of low natural abundance (80 Kr (2.25%) and 130 Xe (4.1%)). a M. b K.

Hepp, W. J¨ager, I. Pak and G. Winnewisser, J. Mol. Spectrosc., 176, 58-63 (1996) Uemura, A. Hara and K. Tanaka, J. Chem. Phys., 104, 9747-9753 (1996)

230

FB. THEORY FRIDAY, JUNE 16, 2000 – 8:30 AM Room: 1009 SMITH LAB Chair: JEAN BLAUDEAU, The Ohio State University, Columbus, OH FB01 10 min 8:30 INTERACTIVE COMPUTER PROGRAM FOR COMPUTER-ASSISTED ASSIGNMENT OF MOLECULAR SPECTRAa MITCHELL STEPHEN E. and JOHN W. FARLEY, Department of Physics, University of Nevada, Las Vegas, NV, 89154. While molecular spectra in textbooks are usually regular, many important spectra are irregular, displaying no obvious pattern. Assigning the quantum numbers of an irregular spectrum can be a vexing problem in pattern recognition, which can be computer-assisted by a program to display the stick spectrum. An interactive plotting program for the Windows platform has been written in Visual BASIC. Input parameters include the molecular constants, the selection rules, and the temperature. The program computes and displays a stick spectrum (including intensities) on the computer monitor, and stores the line list with intensities and quantum numbers in an ACCESS database. The program presently handles vibrational-rotational spectra, but could easily handle electronic spectra as well. The program is particularly useful for irregular spectra, such as asymmetric rotors, and for displaying the effect of variation of the molecular constants on the spectrum. The program is highly interactive: the molecular constants can be changed and the spectrum recomputed and displayed in seconds. a Supported

by DOE/EPSCoR

FB02 BASIS SETS IN CORRELATED EFFECTIVE POTENTIAL CALCULATIONS

15 min

8:42

P. A. CHRISTIANSEN, Department of Chemistry, Clarkson University, Potsdam, New York 13699-5810.

FB03

15 min

8:59 + A FIRST PRINCIPLE EFFECTIVE HAMILTONIAN FOR INCLUDING NON-ADIABATIC EFFECTS FOR H2 AND HD+ DAVID W. SCHWENKE, Mail Stop 230-3, NASA Ames Research Center, Moffett Field, CA 94035-1000. + We compute non-adiabatic corrections for all bound and long lived quasi-bound vibrational levels of H+ 2 and HD for selected rotational levels. This is done using the Bunker and Moss formalism with the correction factors computed from ab initio wavefunctions. The electronic wave functions are expanded in terms of nuclear centered gaussian basis functions. The agreement with accurate calculations is very good: for H+ 2 , most transition frequencies are predicted to within about 0.0001 cm 1 . For HD+ , the results are not quite as good due to the uncertainties in the adiabatic correction. This paves the way for using these techniques to accurately predict the non-adiabatic effects for more complicated molecules.

231

FB04

15 min

9:16

THE FORBIDDEN ROTATION AND ROTATION-VIBRATION SPECTRUM OF H+ 2 P. R. BUNKER, Steacie Institute for Molecular Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada; R. E. MOSS, Department of Chemistry, University of Southampton, Southampton SO17 1BJ, U.K.. Previous studies of the g/u electronic symmetry breaking interaction between the rotation-vibration levels of the X 2 + g + ground electronic state and the A 2 + u first excited electronic state of H2 have focused on explaining the large hyperfine structure observed in some rovibronic transitions between these electronic statesa ; b . The interaction is an ortho-para interaction between levels of the two electronic states. It gives rise to an interesting new electric dipole spectrum that consists of forbidden rotation and rotation-vibration transitions within the X 2 + g ground state involving levels that are near the dissociation limitc . Such a spectrum will occur for any homonuclear diatomic ion having nuclei with non-zero spin such + 21 + as 3 He+ 2 , Li2 and Ne2 . a R.

E. Moss, Chem. Phys. Lett. 206, 83 (1993), and references therein. 17.7 of the book Molecular Symmetry and Spectroscopy, 2nd Edition, by P. R. Bunker and P. Jensen, NRC Research Press, Ottawa 1998. See http://www.nrc.ca/cisti/journals/41653 for the table of contents and ordering information. c P. R. Bunker and R. E. Moss, Chem. Phys. Lett. 316, 266 (2000). b Section

FB05

15 min 9:33 + CALCULATIONS OF THE H3 ROVIBRATIONAL SPECTRUM TO LEVELS NEAR THE BARRIER TO LINEARITY JAMES K. G. WATSON, Steacie Institute for Molecular Sciences, National Research Council, Ottawa, Ontario, Canada K1A OR6. a 1 On the H+ 3 potential surface the saddle point for linear configurations lies about 9930 cm above the lowest vibrational level. For calculations of vibration-rotation energy levels near or above this energy, it is important that the wavefunctions should have the correct behavior at linear geometries. The present work describes calculations using hyperspherical harmonicsb as the angular basis. Previous similar calculations of lower energy levels of H+ 3 have been described by Wolniewicz and Hinzec . Here the line intensities as well as wavenumbers for the 52 band will be discussed. a W.

Cencek, J. Rychlewski, R. Jaquet, and W. Kutzelnigg, J. Chem. Phys. 108, 2831–6 (1998) Wolniewicz, J. Chem. Phys. 90, 371–7 (1989) c L. Wolniewicz and J. Hinze, J. Chem. Phys. 101, 9817–29 (1994)

b L.

FB06 15 min 9:50 ELECTRONIC STRUCTURES AND OPTICAL PROPERTIES OF OPEN AND CAPPED CARBON NANOTUBES W. Z. LIANG, S. YOKOJIMA, and G. H. CHEN, Department of Chemistry, The University of Hong Kong,Pokfulam Road, Hong Kong. Electronic structures of a series of carbon nanotubes with different chiralities, ends and bond lengths are studied systematically. Their absorption spectra are calculated with the localized-density-matrix (LDM) method a . The PM3 model is employed in the calculation. Nature of optical excitations is investigated by examing their reduced single-electron density matrices and a general understanding is obtained. It is found that the optical excitations may be divided into the end modes and tube modes which have different energies and distinctive features and structural dependence. Finite optical gaps have been confirmed for infinite long CNTs. The densities of states of carbon nanotubes are determined at the self-consistent Hartree-Fock level. The calculated absorption spectra and density of states (DOS) are compared well to the experimental results. a S.

Yokojima, and G. H Chen, Chem. Phys. Lett. 292, 379(1998).

Intermission

232

FB07 METHODS OF SCALING QUANTUM MECHANICAL MOLECULAR FORCE FIELDS

10 min

10:30

YURII N. PANCHENKO, Laboratory of Molecular Spectroscopy, Division of Physical Chemistry, Department of Chemistry, M. V. Lomonosov Moscow State University, 119899 Moscow, Vorobiovy gory, Russian Federation, C. I. S. A comparative analysis of various methods of empirical scaling of the quantum mechanical harmonic molecular force fields has been performed. The Pulay method of scaling is stressed to be applicable most successfully in the case where the quantum mechanical force field is determined close to the Hartree-Fock limit. This makes it possible to carry out correction of this force field with maximal retention of the peculiarities inherent in the the molecule under investigation. The solution of the inverse vibrational problem using quantum mechanical force field as a starting one may be considered to be the limiting case of scaling with maximum number of scale factors. Such approach corresponds to the traditional philosophy that searching force field should be closest to the starting onea . On the contrary, the main physical criterion used in the Pulay scaling procedure is closeness of the vibrational modes determined from the scaled force field to the vibrational modes obtained from the starting quantum mechanical force fieldb . a A. G. Yagola, I. V. Kochikov, G. M. Kuramshina and Yu. A. Pentin. “Inverse Problems of Vibrational Spectroscopy”. VSP, Utrecht, The Netherlands, 1999. Chapter 11, p. 259. b Yu. N. Panchenko, J. Mol. Struct. 410-411, 327 (1997).

FB08 10 min TRANSFERABILITY OF SCALE FACTORS VERSUS TRANSFERABILITY OF FORCE CONSTANTS

10:42

YURII N. PANCHENKO, Laboratory of Molecular Spectroscopy, Division of Physical Chemistry, Department of Chemistry, M. V. Lomonosov Moscow State University, Vorobiovy gory, Moscow 119899, Russian Federation, C. I. S. In the techniques for solving the inverse vibrational problem on the basis of quantum-mechanical force fields, it is assumed that the force constants are the same for quasi-equivalent coordinates in similar structural moieties of related moleculesa . Clearly, this approach ignores characteristics of the force field of each particular molecule. Indeed, this concept implies that all responsibility for possible shifts of frequencies and other spectral features of related molecules (to which the force constants are transferred) lies with changes in the inverse kinetic energy matrix. With scaling of quantum-mechanical force fields, the relative errors indroduced during quantum-mechanical calculations of force constants at a certain theoretical level are assumed to be approximately the same for quasi-equivalent coordinates in similar structural fragments of related molecules. This assumption imposes less stringent constraints than the assumption of trasferability of force constants in series of related moleculesb . a A. G. Yagola, I. V. Kochikov, G. M. Kuramshina and Yu. A. Pentin. “Inverse Problems of Vibrational Spectroscopy”. VSP, Utrecht, The Netherlands, 1999. Chapter 11, p. 259. b Yu. N. Panchenko, J. Struct. Chem. 40, 548 (1999) (Russian pagination).

233

FB09 Post-deadline Abstract 15 min 10:54 UNDULATING POTENTIAL ENERGY SURFACES FOR THE RYDBERG STATES OF SMALL MOLECULES CONTAINING A METAL ATOM N. GEUM, Department of Chemistry, Dankook University, Cheonan, 330-714, South Korea; G.-H. JEUNG, Laboratoire Aim´e Cotton (CNRS UPR3321) and ASCI (CNRS UPR9029, Bˆat. 505-506, Campus d’Orsay, 91405 Orsay, France.

FB10 Post-deadline Abstract 15 min 11:11 THE STUDY OF THE MULTIPHOTONIC EXCITES FOR THE DIATOMIC MOLECULAR DISSOCIATION AND THE QUANTUM FLUCTUATIONS THEORY SILVESTRU POPESCU and STEFAN CARCU, Research Institute for Electrical Engineering - ICPE Bistrita Subsidiary Str. Parcului, No. 7, Bistrita Ro - 4400 Romania. A method is presented for dissociation of diatomic molecules, found in a precisely defined atmosphere, through successive absorption of a quantum energy generated by laser effect, at a certain frequency and a certain density of energy, until the energy in this way accumulated became equal with the dissociation energy. The method, based on some of the results previously publisheda , has a better output than classical methods (in which the molecules are bombarded with particles having appropriate energy), allowing practically entire dissociation of all molecules which from that atmosphere. Applying my theoretical results, I have obtained and elaborated a new practical method of ozone productionb , whose efficiency exceeds those of classical methods, using Corona discharge or UV radiation. The extract quantum fluctuation theory, proposed by H. Collen in 1935 and T. Welton in 1951, was used in the present work to determine the probability of the process of molecular dissociation using successive multiphotonic excitation. a S. b S.

Popescu, %ICP Information Newsletter, January, p 207 -208, 1997. Popescu, “A method of ozone generation”, Patents, Romania, Certificate no. 103488.

234

FC. RADICALS AND IONS FRIDAY, JUNE 16, 2000 – 8:30 AM Room: 1000 McPHERSON Chair: PATRICK FLEMING, Santa Clara University, Santa Clara, CA FC01

15 min

8:30

THE HIGH RESOLUTION INFRARED SPECTRUM OF N2 -H+ -N2 D. VERDES, H. LINNARTZ, J.P. MAIER, Department of Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH 4056 Basel, Switzerland; P. BOTSCHWINA, R. OSWALD, Institut f u¨ r Physikalische Chemie, Tammannstrasse 6, D 37077 Go¨ ttingen, Germany; P. ROSMUS, Theoretical Chemistry Group, Universit´e de Marne-la-Vall´ee, F 77454 Champs sur Marne, France; P.J. KNOWLES, School of Chemistry, University of Birmingham, Birmingham, B15 2TT, UK. The first high resolution infrared spectrum of the ionic complex N2 -H+ -N2 and its deuterated derivative is reported. The spectra were obtained in direct absorption in a supersonic planar plasma. The observed rovibrational transitions were assigned to the antisymmetric NN stretching vibration and the spectrum is consistent with a linear centrosymmetric equilibrium structure. The band origin is found at 2352.2364(6) cm 1 and the ground state rotational constant is determined as B00 = 0.081809(14) cm 1 . The assignment is supported by ab initio calculations. The best estimate for the equilibrium ˚ and re (N-H)= 1.277 A. ˚ a struture is Re (NN) = 1.095 A a D.

Verdes, H. Linnartz, J.P. Maier, P. Botschwina, R. Oswald, P. Rosmus, and P.J. Knowles, J. Chem. Phys. 111, 8400 (1999).

FC02 CAVITY RING DOWN SPECTROSCOPY OF CARBON CHAIN RADICALS

15 min

8:47

H. LINNARTZ, T. MOTYLEWSKI, O. VAIZERT, and J.P. MAIER, Department of Physical Chemistry, University of Basel, Klingelbergstrasse 80, CH 4056 Basel, Switzerland. Cavity ring down spectroscopy through a supersonic planar plasma is used to study the electronic transitions of a series of carbon chain radicals in direct absorption.a The gas phase spectra of species of the form C2n H, HC2n H+ , HC2n+1 N+ , NC2n 2 N+ ,b and Cn are compared to the hitherto reported diffuse interstellar band positions. a T.

Motylewski and H. Linnartz, Rev. Sci. Instrum. 70, 1305 (1999). Motylewski, H. Linnartz, O. Vaizert, J.P. Maier, G.A. Galazutdinov, F.A. Musaev, J. Krelowski, G.A.H. Walker, and D.A. Bohlender, Astrophys. J. 531, xxxx (2000) b T.

FC03 10 min 9:04 FAR INFRARED LMR SPECTROSCOPIC MEASUREMENTS OF THE QUASI-LINEAR MOLECULE DCCN W. E. JONES, School of Physical Sciences, University of Windsor, ON, N9E3G5, Canada; F. SUN and R. F. CURL, Rice University, Department of Chemistry and Rice Quantum Institute, Houston, TX 77005; M. D. ALLEN and K. M. EVENSON, National Institute of Standards and Technology, Time and Frequency Division 847, Boulder, CO 80303; J. M. BROWN, Physical and Theoretical Chemistry Laboratory, Oxford University, Oxford OX1 3QZ, United Kingdom. FIR laser magnetic resonance spectra of the quasilinear free radical DCCN, produced by fluorine atom abstraction of deuterium from deuterated acetonitrile (CD3 CN), has been measured at laser wavelengths between 46 and 136 m. The spectra have been analyzed using a triplet asymmetric rotor Hamiltonian. Included in the fitting data set are the millimeter wave data a for the 5 = 0 and 1 levels. This analysis has allowed the determination of some Zeeman constants and the refinement of the molecular constants of DCCN. a M.

C. McCarthy, C. A. Gottlieb. A. L. Cooksy, and P. Thaddeus, J. Chem. Phys. 103, 7779, (1995).

235

FC04 15 min HIGH-RESOLUTION SPECTROSCOPIC STUDIES OF THE 5 BENDING FUNDAMENTAL OF HCCN

9:16

M. D. ALLEN, K. M. EVENSON, Time and Frequency Division, National Institute of Standards and Technology, Boulder, CO 80303-3328; and J. M. BROWN, The Physical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ, United Kingdom. A high-resolution spectroscopic study of the 5 bending fundamental of HCCN has been carried out using far-infrared laser magnetic resonance (FIR LMR) spectroscopic techniques. This study has provided an accurate determination of the 5 separation 3,864,563.78(11) MHz (128.9079721(37) cm 1 ), a more accurate determination of the spin-spin parameters, an improved set of molecular g-factors, and the first observation of hyperfine splittings in the 5 = 1 levels. The analysis of the HCCN radical was done using an ’A’ reduced asymmetric rotor Hamiltonian and included the FIR LMR data (this work), microwave data a , and millimeter-wave data b . A fit was performed including
K = 2 matrix elements and no improvement was observed compared with the fit using
K = 0. Thus, in this analysis there is no support for a slightly bent structure. We can now accurately predict zero field transitions which will be valuable for conducting searches for the 5 fundamental transition in stellar and interstellar sources. a Y.

Endo and Y. Ohshima, J : Chem : Phys : 98, 6618 (1993). C. McCarthy, C. A. Gottlieb, A. L. Cooksy, and P. Thaddeus, J : Chem : Phys : 103, 7779 (1995).

b M.

Intermission

FC05 Post-deadline Abstract 15 min 9:50 HIGH-RESOLUTION INFRARED SPECTROSCOPY OF H2 IN ION CLUSTERS PRODUCED BY -RAY IRRADIATION OF PARAHYDROGEN CRYSTALS TAKAMASA MOMOSE, Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto 6068502, Japan; C. MICHAEL LINDSAY, YU ZHANG, and TAKESHI OKA, Department of Chemistry, Department of Astronomy and Astrophysics, and the Enrico-Fermi Institute, The University of Chicago, Chicago IL, 60637, USA. Infrared absorption of hydrogen molecules in -ray irradiated parahydrogen (p-H2 ) crystals has been studied by a highresolution color center laser spectrometer. The pure vibrational transition Q1 (0) (v=1 0, J=0 0) of H2 becomes infrared active under the strong Coulomb field of ionic species localized in the crystal. We have earlier observed a very sharp
k=0 pure vibrational exciton (vibron) Q1 (0) transition induced by a macroscopic electric field resulting from the imbalance of positive and negative charges a . Here, we report our observation of a new set of extremely sharp lines which appeared at a frequency region to the red of the field free Q1 (0) transition. The spectral widths were as narrow as 60 MHz. These transitions are assigned to the Stark shifted infrared absorption of hydrogen molecules in ion clusters in the p-H2 crystal. The spectral lines remain the same over many days indicating the stability of the ionized system. The observed sharpness and the reproducibility of the spectrum indicate that the local structures of crystals surrounding the ions are homogeneous due to the self-repairing nature of the solid hydrogen. We will discuss the analysis of the spectra and the possible candidates of positive and negative ion cores produced by -ray irradiation of parahydrogen crystals. a T.

Momose, K. E. Kerr, D. P. Weliky, C. M. Gabrys, R. M. Dickson, and T. Oka, J. Chem. Phys. 100, 7840 (1994).

236

FC06 Post-deadline Abstract 15 min 10:07 OBSERVATION AND ANALYSIS IR ABSORPTION SPECTRA OF MIXTURES HF AND HCL WITH CO2 A. KARIMOV, M. KULIEVA and K. KHUDOINAZAROV, Samarkand State University, Samarkand 703004, Uzbekistan. The absolute intensities of fundamental and overtone bands in IR absorption spectra for HCl disolved in liquid CO2 were measured. The multiple growth of fundamental band integral intensity and some decrease (by 20%) of overtone band intensity for HCl under phase transition gas-liquid solution were discovered. The mechanisms of the intensity formation for studied spectra are discussing. It was carried out the nonempiric quantum chemical calculations of intermolecular interactions in HF-CO2 and HCl-CO2 complexes. Calculated and experimental data on electrooptic parameters and intensities of IR absorption spectra for studied systems are comparing and discussing. FC07 Post-deadline Abstract 15 min 10:24 INFRARED SPECTRA OF HYDROGENATED AMORPHOUS CARBON (HAC) AND PARTIALLY HYDROGENATED FULLERENES (PHFs) K. TERESZCHUK, V. GRICHKO, W. W. DULEY, P. F. BERNATH, Departments of Chemistry and Physics, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1. In recent years, interest has developed in studying infrared emission spectra of the circumstellar envelopes of post asymptotic giant branch (AGB) stars and proto-planetary nebulae. Far-infrared spectra of these interstellar phenomena contain a mysterious wide-band feature centred at 20.2 microns (494 cm 1 ). From observations, it has been speculated that the source of the feature is a large complex carbonaceous molecule or solid. Two candidates which have similar characteristic IR absorption bands near or centred at 21-microns have been studied in great detail; hydrogenated amorphous carbon (HAC) molecules (W.W. Duley et al. 1997) and partially hydrogenated fullerenes (PHFs). Absorption spectra of HAC and PHFs have been obtained from 0-4000 cm 1 , and the experimental results will be presented. FC08 Post-deadline Abstract 15 min 10:41 THE TEMPERATURE DEPENDENCE OF THE RAMAN BANDWIDTHS FOR THE HARD MODES OF THE AMMONIUM HALIDES CLOSE TO PHASE TRANSITIONS H. YURTSEVEN, Department of Physics, Istanbul Technical University, Maslak, Istanbul, Turkey. This study gives the temperature dependence of the Raman bandwidths for the 5 (174 cm 1 ) mode of NH4 Cl and for the 5 (177 cm 1 ) mode of NH4 Br. We analyze our observed Raman bandwidths of those phonon modes according to the soft-hard mode coupled model close to the phase transitions in these crystals. Our analyses give that the values of the critical exponent for the Raman bandwidths are = 0:13 for the 5 (174 cm 1 ) mode of NH4 Cl (Tc =241.3K) and for the 5 (177 cm 1 ) mode of NH4 Br (Tc =234K) in the first order phase region of these crystalline systems.

237

FD. METAL CLUSTERS FRIDAY, JUNE 16, 2000 – 8:30 AM Room: 1015 McPHERSON LAB Chair: PAUL DAGDIGIAN, The Johns Hopkins University, Baltimore, MD

FD01 IR SPECTROSCOPY OF GAS PHASE METAL CLUSTERS

30 min

8:30

GERT VON HELDEN, DENIZ VAN HEIJNSBERGEN, GERARD MEIJER, FOM Institute for Plasma Physics Rijnhuizen, Edisonbaan 14, NL-3430 BE Nieuwegein, The Netherlands, http://www.rijnh.nl; MICHAEL A. DUNCAN, Department of Chemistry, University of Georgia, Athens, Georgia 30602, U.S.A., http://www.chem.uga.edu. A method for obtaining vibrational spectra of gas phase metal compound clusters is presented. The clusters are produced in a standard laser vaporization source. The cluster beam enters the interaction region with an IR laser, situated between the plates of a reflectron time-of-flight mass spectrometer. The IR laser is the ”Free Electron Laser for Infrared eXperiments” (FELIX) a , which is continuously tunable over the 5–250 m wavelength region. The laser output consists of ”macropulses” of about 5 sec duration at a repetition rate of 10 Hz. The macropulse is composed of a series of picosecond duration ”micropulses” spaced by one nanosecond. The macropulse energy can be up to 100 mJ, while the bandwidth is about 0.5 – 1 % of the selected wavelength. The IR beam is focused on the molecular beam with a 7.5 cm focal length gold mirror. When the laser wavelength is resonant with an infrared active mode, the cluster can be heated via multiple absorption of photons. In clusters with strong bonding and a relatively low ionization energy electron emission can become competitive with, or even dominant over, dissociation. Tuning the laser while measuring the mass-analyzed ion yield produces an infrared spectrum of the neutral cluster b For titanium-carbide clusters c , the IR spectra showed the presence of C–C bonding in Ti8 C12 clusters, supporting the postulated ”Met-Car” structure. Larger clusters show distinctively different spectra that are in good agreement with the proposed nano-crystal structures. Results from several other metal compound systems will be presented. a G.M.H.

Knippels, R.F.X.A.M. Mols, A.F.G. van der Meer, D. Oepts, and P.W. van Amersfoort, Phys. Rev. Lett. 75, 1755 (1995) von Helden, I. Holleman, G.M.H. Knippels, A.F.G. van der Meer, and G. Meijer, Phys. Rev. Lett. 79, 5234 (1997). c D. van Heijnsbergen, G. von Helden, M.A. Duncan, A.J.A. van Roij, and G. Meijer, Phys. Rev. Lett. 83, 4983 (1999).

b G.

FD02 15 min 9:05 THE INSULATOR TO METAL TRANSITION IN DIVALENT METAL CLUSTERS: A NEGATIVE ION PHOTOELECTRON SPECTROSCOPY STUDY OWEN C. THOMAS, WEIJUN ZHENG SHOUJUN XU, and KIT H. BOWEN, Department of Chemistry, Johns Hopkins University, Baltimore, MD, 21218. Negative ion photoelectron spectroscopy of size selected Mgn=3 35 and Znn=3 20 was used to investigate the electronic structure evolution of magnesium Mgn and zinc Znn clusters. In general, the 3s and 3p-derived bands were observed to merge with increasing cluster size, but local maxima for the 3s to 3p-derived band separation exist for Mg10 , Mg20 , Mg34 , Zn10 , and Zn20 . This is consistent with a shell model interpretation of electronic structure.

238

FD03 15 min 9:22 REACTIVITY OF YTTRIUM CLUSTERS WITH AMMONIA AND IONIZATION POTENTIALS OF YTTRIUM NITRIDE CLUSTERS. E. BENICHOU, E. LANGLOIS and B. SIMARD, Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario, K1A 0R6, Canada; A. MARTINEZ, Departamento de Quimica, Division de Ciencias Basicas e Ingeniera, Universidad Autonoma Metropolitana - Iztapala, A.P. 55-534,Mexico, 09340 Mexico. The reactivity of yttrium clusters with ammonia was studied in two different ways. In a first experiment, the reagent was present in the carrier gas. With this approach, the high-temperature vaporization process leads to the formation of yttrium nitride clusters with the general formula Yn Nn 1 (n=1,2,3...). The ionization potentials (IP) of these clusters have been measured using one-photon photoionization efficiency spectroscopy. Results are compared with DFT calculations which also produce the structures of the most stable forms. In a second experiment, the reactivity of naked yttrium clusters (Yn ) with ammonia was studied in a fast-flow reactor. The clusters react readily with ammonia at each collision and no size dependance was observed. The reaction products observed in this case are radically different from those of the previous experiment. FD04 ZEKE-PFI SPECTROSCOPY AND THEORETICAL CALCUATIONS OF THE InNH3 COMPLEX

15 min

9:39

GRETCHEN K. ROTHSCHOPF, SHENGGANG LI, JIMMYE SHANNON PERKINS, AND DONGSHENG YANG, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055. InNH3 was prepared with pulsed laser vaporization of an indium rod and subsequent reactions with ammonia seeded in helium gas. The complex was identified with laser ionization time-of-flight mass spectrometry and studied with single-photon ZEKE-PFI (zero kinetic energy pulsed field ionization) spectroscopy. The ZEKE-PFI spectrum shows two progressions in the 39400-40800 cm 1 regions with the bandwidth of 5 cm 1 . From the spectral measurements, we have obtained the ionization potential (39689 cm 1 ) and the In-NH3 stretching frequencies (3+ = 230 cm 1 and 3 = 140 cm 1 ) of the complex. In addition to the experimental work, we have used density functional and ab initio methods to calculate the geometries, vibrational frequencies, and electronic energies of the ground states of the neutral and ionic complexes. The theoretical results will be discussed in the comparison with the experimental observations. FD05 ZEKE-PFI SPECTRA OF AlNH3 AND AlNH2 (CH3 )

15 min

9:56

GRETCHEN K. ROTHSCHOPF, JIMMYE SHANNON PERKINS, SHENGGANG LI, AND DONGSHENG YANG, Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055; JUN MIYAWAKI, National Institute of Materials and Chemical Research, National Institute for Advanced Interdisciplinary Research, Higashi, Tsukuba, Ibaraki 305, Japan. The aluminum complexes were prepared in a metal cluster source and identified with a time-of-flight mass spectrometer. The electronic spectra of the complexes were measured with single-photon ZEKE-PFI (zero electron energy pulsed field ionization) technique. The ZEKE spectrum of AlNH3 shows vibronic transitions from two spin-orbit levels of the neutral ground electronic state, which allows the measurements of the following spectroscopic constants: ionization potential (39746 cm 1 ), spin-orbit splitting (58 cm 1 ), Al-NH3 symmetric stretching frequencies (!3+ = 339 cm 1 , !3+ x+ 3 = 3.1 cm 1 , and 3 = 227 cm 1 ), and Al-N symmetric bending frequency (6+ = 557 cm 1 ). The ZEKE spectrum of AlNH2 (CH3 ) displays at least four progressions, from which two vibrational modes (365 and 160 cm 1 ) may be identified.

239

AUTHOR INDEX A ABEBE, Y. – ME06 ABEL, B. – TG07 ADAM, A. G. – TA11, WF14 AGREITER, J. K. – RF02 AIUCHI, K. – RA12 AKHMEDJONOV, A. – TE12, TE13 AKHMEDJONOV, R. – TE12 ALBERT, S. – TH02 ALEXANDER, M. H. – FA01 ALIKHANI, M. E. – RF10 ALLAMANDOLA, L. J. – WI05 ALLEN, M. D. – TE02, FC03, FC04 AMANO, T. – RC04, RC10 AOAEH, B. – ME06, ME07 APPLEGATE, B. E. – TF02, RD03, RD04 APPONI, A. J. – MH09, MH10, MH12, RC08 ATWELL, J. R. – TF02 AUWERA, J. V. – TE07, TE08, WG06, WG07 AUWERAER, M. V. D. – MI13 AYDIN, M. – RA07

B BABA, M. – TG12 BAEK, S. J. – MF05, FA07 BAILLEUX, S. – WE06, WE07 BALFOUR, W. J. – RA09 BALL, C. D. – ME06, ME07, TF12 BALLY, T. – WI05 BAR, I. – TD12 BARABASH, A. – WI07 BARCKHOLTZ, T. A. – RD01, RD03, RD04 BARGHEER, M. – WI01, WI09 BARTELS, J. A. – MI08 BATAIEV, M. M. – MI13 BAUDER, A. – TH13 BAUMANN, C. A. – TB10 BEAKY, M. M. – TH07 BEARPARK, M. J. – RD02, RH01 BECKERS, H. – MH06 BENATH, P. – WG01 BENICHOU, E. – FD03 BENNER, D. C. – ME06, ME07, WG03, WG09, WG10, WG11, WG12, WG13

BERNARDI, F. – RH01 BERNATH, P. F. – WF01, WF06, WF07, WF08, WF14, RA05, RC10, FC07 BEZANT, A. J. – TA03, RD04 BILLINGHURST, B. – RG05 BIZZOCCHI, L. – MH11 BLAKE, T. A. – MF14, TD05, TE09 BLANCAFORT, L. – RD02 BLASIOLE, B. – MI08 BLAUDEAU, J. – RH04, RH05 BLAUDEAU, J.- P. – RH02 BLESSING, N. – MG10 BOGEY, M. – MH06 BOLTNEV, R. E. – WI13, WI14 BONDOC, E. – RG03 BONEBERG, J. – TC05 BOONE, C. – TG11, WG01 BORST, D. R. – MI01, TD04, RB03, RB04 BOSCH, E. – WH05 BOTSCHWINA, P. – ME02, ME03, MH11, TC06, TC11, WH08, RC03, FC01 BOUDON, V. – RD06 BOUSQUET, R. R. – RF06 BOWEN, K. H. – MG05, MG06, FD02 BREIDUNG, J. – MH06 BRENDEL, K. – RE06 BROWN, J. M. – WF10, WH05, FC03, FC04 BROWN, L. R. – WG04, WG09, WG10, WG11, WG12, WG13 BROWN, M. G. – MF07 BROWN, S. T. – WH04 BROZELL, S. R. – RH02, RH03 BRUEHL, F. R. – TB03 BRUPBACHER-GATEHOUSE, B. – MH04 BUNKER, P. R. – WH02, WH03, FB04 BURKART, S. – MG10 BURROUGHS, A. – WI06, FA08 BURROWS, J. P. – TG10 BURSTEN, B. E. – RH04, RH05 BUTLER, C. J. – MI01 BUTLER, R. A. H. – MH05, TH02 BUYDENS, L. M. C. – MI03 ¨ BURGER, H. – MH06, TE01, WG06

C

CABLE, J. R. – RB07, RB08, RB09 CALLEGARI, A. – MF10 CALLEGARI, C. – TB01, TB02 CAMPARGUE, A. – TG10 CANAGARATNA, M. R. – WG05 CAO, H. – WF13, WG02, WG08 CARCU, S. – FB10 CARNEY, J. – RB08, RB09 CARTER, C. C. – TF02, FA02 CATALANO, T. – TB06 CERNICHARO, J. – WA04 CHAE, S. Y. – TF13 CHAN, M. – RC04 CHANDRA, N. S. – TB10 CHANG, B. – TA03, TA04 CHANG, J. – TF04, RB01 CHARVAT, A. – TG07 CHELIKOWSKY, J. R. – MG03 CHEN, G. H. – FB06 CHEN, H. – WF02 CHEN, H. M. – RA04 CHEN, P. – TF05 CHEN, X. – TD12 CHEN, X. L. – TF10 CHEN, Y. – TB11, TF04, RB01 CHEUNG, A. S. – WF02, RA10, RA11 CHIROKOLAVA, A. – RB12 CHOI, J. – FA07 CHRISTEN, D. – TH13, TH14, RE13 CHRISTIANSEN, P. A. – FB02 CHUANG, C. – MF08 CLARK, J. – FA06 CLEGG, S. M. – MI10 CLEVENGER, J. O. – TG02, TG03 CLOUTHIER, D. J. – TA10, TA11, RA06, RD08 COE, J. V. – MG09 COHEN, E. A. – MH02, MH03 CONJUSTEAU, A. – MF10, TB01, TB02 COSBY, P. C. – TA01 COSTEN, M. – TA04 COSTES, M. – RC12 COUDERT, L. – RE13 COXON, J. A. – MH13, WF05 COY, S. L. – TI11, WG05 CRADDOCK, M. – RE04 CRAIG, N. C. – TH11, RE07, RG02 CREMER, D. – RE13 CRONIN, T. J. – RB12

240

CROZET, P. – WH05 CURL, R. F. – FC03

RG09

E D DAGDIGIAN, P. J. – WF09, RF01, FA01 DAI, H.- L. – TF08 DAIRE, S. E. – FA03 DALFOVO, F. – TB01 DANNEMILLER, J. – TH06 DAUMONT, L. – WG07 DAVIES, P. B. – TF03 DAVIS, A. V. – MG02 DAVIS, S. – MI04, WA01 DE GELDER, R. – MI03 DE LUCIA, F. C. – MF01, MH05, MH07, TH02, TH08, WE04, RC09 DEEV, A. – RF08 DELON, A. – TG04, TG05, TG09, TG10 DELUCIA, F. C. – ME06, ME07 DEMERS, J. R. – MH07 DENG, W. – TF01 DEPPE, S. F. – TG07 DERAMO, M. – TH01 DEVDAS, S. – WI10 DEVI, V. M. – ME07, WG03, WG09, WG10, WG11, WG12, WG13 DIBBLE, T. S. – TF01 DICKINSON, C. S. – MH13 DIETRICH, P. – WI01, WI09 DING, X. D. – WI02 DMITRIEV, Y. A. – WI14 DONOVANG, K. – WI09 DOPFER, O. – RC06, RC07 DOWDYE, E. H. – ME13 DREAN, P. – MH06 DREHER, S. – TG10 DREW, B. R. – RG04 DROUIN, B. – TH06 DROUIN, B. J. – MH02, TH04, RE11, RE14 DUAN, Y. – RE09, RG12 DUCA, M. D. – MI10 DUDEK, R. – MI12 DULEY, W. W. – FC07 DULICK, M. – WG04 DUNCAN, M. A. – RF02, RF04, FD01 ´ P. – TG04, TG05, TG09, DUPRE, TG10 DURIG, J. R. – RG04, RG07, RG08,

ELHANINE, M. – MG02 ELLZY, M. W. – TD10 ENDO, Y. – TA08, TA09, TF09, WE02 ERNST, W. E. – TB03, RD05 ESPOSTI, C. D. – MH11 EVANS, C. – MI12 EVANS, C. J. – TH05, WE08, WE09, WE10 EVENSON, K. M. – TE02, FC03, FC04

F FAN, W. Y. – TF10 FANG, N. – RA08 FARLEY, J. W. – TC07, FB01 FARNIK, M. – TD06, WA01 FAROOQUI, A. S. – MI07 FEDOROV, A. V. – RB07, RB08, RB09 FELLERS, R. S. – MF07 FIACCO, D. L. – TH03, RE04 FIELD, R. W. – TG02, TG03, WG05 FISCHER, I. – TF05 FLAUD, J. – WG06 FLAUD, J.- M. – TE01 FLEMING, P. E. – RH06 FLENIKEN, J. – FA01 FLORIO, G. M. – RB11 FOCSA, C. – WF07, WF08 FOLTYNOWICZ, R. J. – TF06, TF07 FRISCHKORN, C. – MG02 FROMHERZ, R. – TC05 FUCHIGAMI, K. – TH12 FUKUSHIMA, M. – RF07 FURLANETTO, M. R. – TC09 FUSHITANI, M. – WI08

G GAMBLIN, S. D. – FA03 ¨ G. – MG03, MG10, GANTEFOR, TC05 GARAVELLI, M. – RH01 GERHARDS, M. – RB10 GERRY, M. C. L. – MH13, TH05, WE08, WE09, WE10 GEUM, N. – FB09

GILBERT, J. V. – WI12 GILBERT, T. – TF05 GITTINS, C. M. – TG02 GLAB, W. L. – TA02 GLINKA, Y. D. – TB11 GOLDMAN, A. – WG03 GOLUBYATNIKOV, G. Y. – WG14 GOODRIDGE, D. M. – MH03 GOOVAERTS, E. – TI08 GOPALAKRISHNAN, S. – TF02, TH08, WE04 GORDON, E. B. – WI13, WI14 GORDON, V. D. – MH10, MH12 GOTTFRIED, J. – WF04 GOTTLIEB, C. A. – MH09, RC08 GOUGH, K. – RG05 GOUNEV, T. K. – RG09 GOYETTE, T. M. – MH07, TH02 GRAHAM, W. R. M. – WI02, WI10, WI11 GRANT, E. R. – TF06, TF07, FA06 GRAY, J. A. – WF04 GREBENSHCHIKOV, S. – TI13 GRICHKO, V. – FC07 GRIEVES, G. A. – RF02 GRONER, P. – RE08 GRUEBELE, M. – MA03, TD03, TI02, TI10 GRUENLOH, C. J. – RB11 GUARNIERI, A. – WG14 GUELACHVILI, G. – WG09 GUENTHER, B. D. – MH07 GUIRGIS, G. A. – RG07, RG08, RG09 ¨ GUTHE, F. – TC02

H HAGEMAN, J. A. – MI03 HALASINSKI, T. M. – WI05 HALES, D. A. – WF03 HALL, G. E. – TA04 HALONEN, L. – ME10, TI05, TI06 HALONEN, M. – TD06, WA01 HALPERN, J. B. – TF08 HAMILTON, I. P. – MG08, RF09 HANSEN, N. – MH01, TA05, TA06 HAO, X. – RG12 HARADA, K. – MF04, MF11, WE01, WE06, WE07 HARIDASS, C. – ME13, TA12 HAUSCHILDT, J. – TC11, TI13 HEAVEN, M. C. – WH07, WI06, FA08

241

HEDDERICH, H. G. – TF06 HEGELUND, F. – TH14 HEIJNSBERGEN, D. V. – FD01 HEILLIETTE, S. – TG04, TG05, TG10 HELDEN, G. V. – FD01 HELMINGER, P. – MH05, TH02 HEPBURN, J. W. – MA01, TC08, FA04, FA05 HEPP, M. – TE08 HERBST, E. – TC04, RC09 HERMAN, M. – TE08 HERMANN, A. – TH13 HERNANDEZ, A. J. – ME04, ME05, RH08, RH09 HERREGODTS, F. – TE08 HERRMANN, W. – TH06 HIGGINS, K. J. – MF09, RE03 HIRANO, T. – WH09, RA12, RH07 HIRAO, T. – WF01, WF06, RC10 HIROTA, E. – RE12 HO, K. – MG03 HOCHLAF, M. – TC03 HOLLENSTEIN, U. – TG01 HORE, N. R. – TF03 HORNEMAN, V.- M. – RG06 HOSTUTLER, D. A. – TA10, RD08 HOUGEN, J. T. – TD02, TI01 HU, Q. J. – TC08, FA04, FA05 HU, X. K. – TC08, FA04, FA05 HUANG, Y. – RA03 HUESTIS, D. L. – TA01 HUNT, P. – RH01 HUNT, S. W. – TH03, RE04 HUR, S. W. – RG09 HURTMANS, D. – TE08 HUSHVAKTOV, H. A. – TB09

I IMAI, K. – ME12 IMAJO, T. – WF11 INDRIS, O. – TH06 ISHIBASHI, C. – ME09, ME12 ISHIBASHI, T. – TA09 ISHIGURO, M. – MF02, MF03, MF04 ISHIWATA, T. – RF07 ITONO, S. S. – RA12, RH07

J JACKSON, M. – TE02

JACON, M. – TG09 JACOX, M. E. – WI03, WI04 JAKUBEK, Z. J. – RA09 JANCZYK, A. – RF05 JANSEN, A. – RB10 JENSEN, J. O. – TD01, TD10, TD11 JENSEN, P. – WH02, WH03 JEUNG, G.- H. – RC11, RC12, FB09 JIANG, X. – TG02, TG03 JOHNS, J. W. C. – RG11 JOHNSON, M. S. – RF03 JOLIBOIS, F. – RH01 JONES, W. E. – FC03 JOO, D. – MF05 JOST, R. – TG04, TG05, TG09, TG10 JUDGE, R. H. – MI05 JUMABOEV, A. – TB08, TB09 ¨ JAGER, W. – WE12, WE13, RE05

K KACHANOV, A. A. – WG05 KALEDIN, A. L. – WH07 KALINOVSKI, I. J. – TF10 KAN, P. J. M. V. – TI08 KANAMORI, H. – MH08 KANG, C. – RB06 KARIMOV, A. – FC06 KASAHARA, S. – TG12 KASAI, Y. – WE02 KATO, H. – TG12 KATO, T. – MH08 KATSUKI, H. – TB07 KATZ, D. R. – TF01 KAWAGUCHI, K. – MH03 KAWASHIMA, Y. – RE12 KELLERMAN, T. – WF12, WF15 KERENSKAYA, G. – WH07 KERMODE, S. M. – WF10 KESKE, J. – TD07, TD09 KEUTSCH, F. N. – MF07 KHASANOV, K. – TI07 KHMELENKO, V. V. – WI13 KHUDOINAZAROV, K. – FC06 KIM, B. – MF05, FA07 KIM, D. W. – RC11 KIM, K. H. – RC12 KIM, K. S. – RC11 KIM, Y. – FA01 KIM, Y. H. – RC12 KINGSTON, C. T. – RA08 KIRSCHNER, K. N. – RF04 KJAERGAARD, H. G. – RG05

KLEE, S. – RG12 KLEFFMANN, J. – WG06 KLEINERMANNS, K. – RB02, RB10 KLEMPERER, W. – MF08, MF09, RE03 KLIPP, B. – MG10 KNIGHT, A. M. – RF02 KNOWLES, P. J. – FC01 KOBAYASHI, K. – TA07 KOBAYASHI, Y. – WF11 KOLODZIEJSKI, N. – ME07 KONARSKI, J. – ME01 KORTER, T. M. – MI01, MI02, MI08 KOUROGI, M. – ME12 KRAEMER, G. T. – RA01 KRAEMER, W. P. – WH03 KRISTOFFERSON, A. K. – RG11 KRUSHINSKAYA, I. N. – WI13 KUCZKOWSKI, R. L. – WE11, RE01, RE02 KUKOLICH, S. – TH06 KULIEVA, M. – FC06 KUMAGAI, M. – MH08 KUNZMANN, M. – RG01 ¨ KOPPEL, H. – MG11, WH06 ¨ KUPPER, J. – RB02

L LAANE, J. – RG03 LAFFERTY, W. J. – TE01 LAKIN, N. M. – TC02, TC03 LAMBETH, A. – WF12, WF15 LANG, S. – WI14 LANGE, K. R. – TE11 LANGHOFF, P. W. – RF03 LANGLOIS, E. – FD03 LARSON, A. – RE13 LAVRICH, R. J. – TH09, TH10, TH11, TH15 LE ROY, R. J. – WF07, RA01, RA02, RA03 LEE, H. – TI12 LEE, H. S. – RC11 LEE, S. K. – TF13 LEE, Y. – MF05, FA07 LEE, Y. S. – RC11, RC12 LEES, R. M. – RG11 LEHMANN, K. K. – MF10, TB01, TB02, TB04, TB05, TG08 LEI, J. – WF09 LEIDERER, P. – TC05 LEIWEKE, R. J. – TG06

242

LEMPERT, W. R. – TG06 LEOPOLD, K. R. – TH03, RE04 LESARRI, A. – TD01, WE10 LETENDRE, L. – TF08 LEUNG, H. O. – WE05 LEUNG, J. W. – RA11 LEWIS, E. K. – ME05 LI, G. – WF06 LI, G. P. – MG08, RF09 LI, H. – WF07, WF08, RD08 LI, R. – TF04, RB01 LI, S. – FD04, FD05 LI, X. – ME05 LI, Y. – WF02 LIANG, W. Z. – FB06 LIAO, D. C. K. – RA08 LILIEN, M. D. – TF01 LIM, E. C. – MI05 LIN, S. – TB11 LINDSAY, C. M. – RC05, FC05 LINDSAY, D. M. – RA07 LINEBERGER, W. C. – MG01 LINNARTZ, H. – RC08, FC01, FC02 LINTON, C. – WF05 LITORJA, M. – RC01 LIU, B. – MG03 LIU, D.- K. – TF08 LIU, H. – MI05 LIU, Y. – RE05 LIU, Z. – TF03 LIVINGSTONE, R. J. – TF03 ´ LIEVIN, J. – WF14 LOBO, J. D. – MG04, RF08 LOCHNER, J. M. – TD10 LOCK, M. – RG02, RG11 LOMBARDI, J. R. – RA07 LOVAS, F. J. – TD01 LOW, G. – RG05 LOZEILLE, J. – FA02, FA03 ¨ LOETE, M. – RD06 LUC, P. – RC11, RC12 LUGEZ, C. L. – WI03

M MA, Y. – RB12 MABUCHI, H. – MF10 MACK, H. – TH13 MAEDA, A. – RC10 MAGNIER, S. – TC10 MAHALIDGE, D. – TB10 MAIER, J. P. – TC02, FC01, FC02 MAJOR, H. E. – TA12 MAKI, A. – ME11

MAMATOV, Z. – TB09 MANCERON, L. – RF10 MANTZ, A. W. – ME06, ME07 MANZANARES, C. E. – ME04, ME05, RH08, RH09 MARKOV, V. N. – WG14 MARR, A. J. – TA04, TA05, TA06 MARTIN, F. – RA04 MARTINEZ, A. – FD03 MARTYNENKO, M. V. – WI13 MATSIKA, S. – RH02, RH10 MATSUSHIMA, F. – ME08 MATSUSHITA, M. – MH08 ´ B. – TD11, RE07 MATE, MCCARGAR, J. W. – TH09 MCCARTHY, M. C. – MH09, MH10, MH12, TF12, RC08 MCCOY, A. B. – TI09, TI12, RE09, RG12 MCDOWELL, R. S. – TD05 MCKELLAR, A. R. W. – MF12, MF13, FA10 MCLEOD, S. – WG01 MEERTS, W. L. – MI03, TI08 MEHROTRA, S. C. – TB12 MEIJER, G. – MA02, FD01 MEINANDER, N. – RG03 MELCHIOR, A. – TD12 MELLAU, G. – ME11 MELLAU, G. C. – RG12 MELNIK, D. G. – TH08, WE04 MELVILLE, T. C. – WF05 MENGEL, M. – MF01 MERER, A. J. – WH01, RA06, RA08, RA10, RD08 MERKER, U. – TB04, TB05 MERKT, F. – MH04, TG01, WA02 MEYER, H. – FA01 MIANI, A. – TI05 MICHELOT, F. – RD06 MIKI, M. – WI08 MILLER, C. E. – MH02 MILLER, J. S. – RC02 MILLER, R. E. – MF02, MF03, TE04, TE05, TE06 MILLER, T. A. – TA03, TF02, TF11, TH08, WE04, RD03, RD04, FA02 MINA-CAMILDE, N. – ME04 MINEMOTO, S. – TC05 MIRON, R. A. – TB03 MISONO, M. – TG12 MISRA, P. – ME13, TA12 MITCHELL, S. E. – TC07

MITSUI, Y. – RH07 MIYAWAKI, J. – FD05 MIZOGUCHI, A. – WE06, WE07 MOAZZEN-AHMADI, N. – TE10 MOLSKI, M. – ME01 MOMOSE, T. – TB07, WI08, FC05 MOON, J. H. – RC12 MOORE, C. B. – TF10 MOORE, D. T. – TE04, TE05, TE06 MORE, N. M. – TB12 MORRIS, K. – RG03 MORSE, M. D. – WF03 MORUZZI, G. – RG01 MOSS, R. E. – FB04 MOTYLEWSKI, T. – FC02 MOULE, D. C. – MI05 MUKHOPADHYAY, I. – RG12 MULCH, M. L. – WI12 ¨ MADER, H. – MH01, RE06 ¨ MADER, H. J. – WG14 ¨ MULLER, H. S. P. – MH02 ¨ MULLER, J. – MG03, MG10, TC05 ¨ MUNZER, H. J. – TC05

N NADGARAN, H. – RE15 NAGASHIMA, U. – WH09, RA12, RH07 NAKAJIMA, M. – TA08 NAKASHIMA, Y. – WF11 NASHED, Y. – RG08 NASHED, Y. E. – RG07 NAULIN, C. – RC12 NESBITT, D. – TD06, TI06 NESBITT, D. J. – WA01 NEUMARK, D. M. – MG02, TC09 NIEMEYER, J. – TH13 NIKI, H. – RA09 NIKOLAEV, A. – MI09 NILLES, J. M. – MG05, MG06

O O’BRIEN, J. J. – WF13, WG02, WG08 O’BRIEN, L. – WF12, WF13, WF15 OBERHAMMER, H. – TH13 ODAKA, E. – WH09 OERTEL, C. M. – TH11, RG02 OERTEL, D. C. – RG02 OESTERLING, L. C. – RC09 OGATA, T. – TH12

243

OGUT, S. – MG03 OHASHI, N. – TD02 OHSHIMA, Y. – TF09 OKA, T. – RC05, FC05 OKUMURA, M. – MG04, RF03, RF08 OLIVUCCI, M. – RH01 OLKHOV, R. V. – RC06, RC07 ONAE, A. – ME12 ORPHAL, J. – TG10 ORTIGOSO, J. – TI01 OSMANN, G. – WH02, WH03 OSMANOV, B. S. – TB08 OSMANOV, S. A. – TB09 OSTERBROCK, D. E. – TA01 OSWALD, R. – ME02, ME03, FC01 OYEYEMI, O. A. – WE05 OZIER, I. – RG06

P PACHKOV, M. – TC02 PALM, H. – TG01 PALMER, M. H. – TH14 PANCHENKO, Y. N. – FB07, FB08 PANOV, S. I. – TG03 PAPLEWSKI, P. – MH06 PARMENTER, C. S. – MI10, MI11 PATE, B. H. – TD07, TD08, TD09 PATWARI, G. N. – MI06 PAWELKE, G. – TE01, WG06 PEARMAN, R. – TI02 PEARSON, J. C. – TH04, RE11, RE14 PEEBLES, R. A. – WE11 PEEBLES, S. A. – RE01, RE02 PELMENEV, A. A. – WI13, WI14 PEREVALOV, V. I. – WG07 PERKINS, J. S. – FD04, FD05 PERMOGOROV, D. – ME10 PERRIN, A. – WG03 PERRY, D. S. – RB12, RG10 PESONEN, J. – TI05 PETERSEN, P. B. – MF07 PETKIE, D. T. – TH02 PETRACO, N. D. K. – WH04 PETRAGLIO, G. C. L. – TG01 PHILLIPS, J. A. – TE11 PIBEL, C. D. – TF08 PICHLER, M. – RA04 PICKETT, H. M. – RE11 ´ N. – WG09 PICQUE, PINCHEMEL, B. – WF07, WF08 PITZER, R. M. – RH02, RH03,

RH04, RH10, RH11 PIVONKA, N. L. – TC09 PLEGGE, K. S. – TE11 PLUSQUELLIC, D. F. – MI04, TD11 POLIAKOFF, E. D. – RC02 PONDILLO, P. L. – TH01 POPESCU, S. – FB10 POPOV, E. A. – WI13, WI14 PRASAD, M. D. – MI06 PRATT, D. W. – MI01, MI02, MI08, MI09, TD04, RB03, RB04, RB05, RB06 PRIDE, L. D. – TA07 PUSHKARSKY, M. – TF11

Q QTAITAT, M. A. – RG08

R RADCLIFF, M. R. – TB04, TB05 RADE, R. M. – RC05 RADJABOV, U. N. – RG14 RAHMATULLAEV, U. – TE13 RAM, R. S. – WF14, RA05 RAN, Q. – RA10, RA11 RASULOV, A. – TE12 REDDIC, J. E. – RF04 REDDY, S. P. – TE03 REHO, J. – TB04, TB05 REID, S. A. – MF06, FA09 REINHARD, I. – TB01, TB02 REINHART, B. – MG08 REY, M. – RD06 REYNARD, L. – WE09 REYNOLDS, D. L. – ME04 RHEA, R. L. – TH09 RIBBLETT, J. W. – RB03 RINSLAND, C. P. – WG03, WG09, WG10, WG11, WG12, WG13 RITCHIE, G. – TA04 RITTBY, C. M. L. – WI02, WI10, WI11 RIXON, S. J. – RA06 ROBB, M. – RD02, RH01 ROBBINS, D. L. – WI11 ROBINSON, J. D. – TF06, TF07 ROSENWAKS, S. – TD12 ROSMUS, P. – TC03, FC01 ROSS, A. J. – WH05, RA04 ROTH, D. – RC06 ROTHSCHOPF, G. K. – FD04, FD05

RUBINOFF, D. S. – TH05, WE10 RUDE, B. S. – TB06 RUSCIC, B. – RC01 RUSSELL, D. K. – TF03 RUSSIER-ANTOINE, I. – RA04 RUSTAMOV, I. – TE13 RYBAK, K. – TI11 RYU, J. – MF05

S SAARINEN, M. – ME10 SAKAKIBARA, N. – TH12 SAKURAI, S. – RG03 SALAMA, F. – WI05 SALAZAR, M. C. – ME04, ME05, RH08, RH09 SAMS, R. L. – TD05, TE09, WG10, WG11 SAMUELS, A. C. – TD01, TD10, TD11 SANCHEZ-GALVEZ, A. – RH01 SANETO, R. – ME09 SANTHANAM, V. – RH12 SASADA, H. – ME09, ME12 SATHYAN, N. – RH12 SAYKALLY, R. J. – MF07, TB06 SCHAEFER, H. F. – WH04 SCHALLER, R. D. – TB06 SCHEBLYKIN, I. G. – MI13 SCHINKE, R. – TC11, TI13 SCHMATZ, S. – TC11 SCHMITT, M. – RB02 SCHORK, R. – MG11 SCHRODERUS, J. – RG06 SCHULZ, B. – ME02, MH11 SCHWENKE, D. W. – FB03 SCHWENTNER, N. – WI01, WI09 ¨ SCHAFER, M. – TH13, WE03 SCOLES, G. – MF10, TB01, TB02, TB04, TB05 SEARS, T. J. – TA04, TA05, TA06, TA07 SEIKI, K. – TF09 SEILER, R. – TG01 SETO, J. Y. – RA02 SHA, W. – TA11 SHANG, H. – RC01 SHARPE, S. W. – TD05, TE09 SHEEHY, J. I. – RF03 SHEMESH, L. G. – TF01 SHERMATOV, E. N. – ME14, RG13, RG14 SHESTAKOV, A. F. – WI13

244

SHI, Q. – RA11 SHIBUYA, K. – RA12 SHIEH, J. – RB01 SHIELL, R. C. – TC08, FA04, FA05 SHVARTSBURG, A. A. – MG03 SICKAFOOSE, S. M. – WF03 SIMARD, B. – RA09, FD03 SIMONS, J. – TC01 SIU, K. W. M. – MG03 SKATRUD, D. D. – TH07 SKELTON, R. – WF08, WG01 SLANGER, T. G. – TA01 SMEYERS, Y. G. – TI03, TI04 SMITH, M. A. H. – ME06, ME07, WG03, WG09, WG10, WG11, WG12, WG13 SMITH, T. C. – TA11, RD08 SOBHANADRI, J. – RH12 SOLCA, N. – RC07 SOMMERFELD, T. – MG07 SPOTTS, J. M. – RF03 SRIVASTAVA, H. – MF10 STAMP, C. – TE03 STEIMLE, T. C. – WA03, RF05, RF06 STEINFELD, J. I. – TI11, WG05 STEPHEN E., M. – FB01 STEPHEN, T. M. – WG03 STOLL, H. – ME02, RC03 STONE, T. A. – MI11 STRICKLER, B. – TD03 STWALLEY, W. C. – RA04 SUENRAM, R. D. – MI04, TD01, TD10, TD11, RE07, RE13 SUMIYOSHI, Y. – TA08, TA09, TF09, WE02 SUN, F. – FC03 SUN, Z. D. – ME08 SUZUMURA, K. – ME12

T TAKAGI, K. – ME08, RE10 TAKETSUGU, T. – WH09, RA12, RH07 TAM, W. S. – RA10, RA11 TANAKA, K. – MF04, MF11, WE01, WE06, WE07, WF11 TANAKA, T. – MF04, WF11 TANG, J. – TF09 TANG, S. – RA08 TAO, J. – RG07 TARANTELLI, F. – MG07 TASHKENBAEV, U. N. – TB08,

TB09 TASHKUN, S. A. – WG07 TASIC, U. S. – MI11 TATAMITANI, Y. – TH12 TAYLOR, C. – TB10 TEFFO, J. – WG07 TEMPS, F. – MH01 TEMSAMANI, M. A. – RB12, RG10 TERESZCHUK, K. – FC07 TERZIEVA, R. V. – TC04 THADDEUS, P. – MH09, MH10, MH12, TF12, RC08 ´ P. – TG09, TG10 THEULE, THIEL, W. – MH06 THOMAS, O. – MG06 THOMAS, O. C. – FD02 THOMPSON, T. – TA02 THOMPSON, W. E. – WI03, WI04 TIMLIN, R. E. – TH01 TOBIN, J. G. – TB06 TOROK, C. R. – TH10, TH15 TOTH, R. A. – WG04 TREMBLAY, B. – RF10 TSOULI, A. – WF14 TSUJI, K. – RA12 TSUNEKAWA, S. – ME08 TUBERGEN, M. J. – TH09, TH10, TH11, TH15 TUKHVATULLIN, F. H. – TB08, TB09 TULEJ, M. – TC02

U UNTERBERG, C. – RB10 UY, D. – WA01

V VAIZERT, O. – FC02 VARBERG, T. D. – RA06 VARGHESE, G. – TE03 VASCONCELLOS, E. C. C. – TE02 VELASQUEZ, J. – RF04 VERDES, D. – FC01 VETTER, R. – RC11, RC12 VIANT, M. R. – MF07 VILLA, M. – TI03, TI04 VITUKHNOVSKY, A. G. – MI13

W WACHSMUTH, U. – TG07

WALKER, A. H. – RE07, RE13 WALKER, A. R. H. – TD11 WALKER, K. A. – FA10 WALKER, N. R. – MH13 WALTERS, A. D. – MH06 WANG, C. J. – TF01 WANG, H. – RA04 WANG, L. – RD07, RE10 WANG, Q. – RH11 WANG, S. L. – WI02 WANG, S.- X. – RG06 WANG, X. – RB12 WARREN, R. D. – RE08 WATEGAONKAR, S. – MI06 WATSON, J. K. G. – FB05 WEBER, P. – MI12 WEHRENS, R. – MI03 WEIRAUCH, G. – TG10 WEIS, A. – WI14 WEISS, J. – TI13 WELLS, N. P. – TE11 WESOLEK, D. M. – TH01 WESTPHAL, A. – RB02 WHITHAM, C. – WE01 WHITHAM, C. J. – MF04, MF11 WIDIYATMOKO, B. – ME12 WIG, R. W. – TH01 WIJNGAARDEN, J. V. – WE12 WILLEY, D. R. – TH01 WILLNER, H. – TH13 WILSON, K. R. – TB06 WINNEWISSER, B. P. – RG01, RG11 WINNEWISSER, M. – RG01 WINTER, P. R. – TG08 WITONSKY, S. K. – WG05 WONG, C. – RF03 WONG, C. K. – MG04, RF08 WONG, V. – TI10 WRIGHT, T. G. – FA02, FA03 WU, J. – TF04, RB01

X XIA, C. – MF12, MF13 XIN, J. – MF06, FA09 XU, C. – RC01 XU, L. – RB12, RG10, RG11 XU, S. – MG05, MG06 XU, W. Z. S. – FD02 XU, Y. – MF13, WE13

Y

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YURTSEVEN, H. – FC08 YAMAGUCHI, Y. – WH04 YANG, D. – FD04, FD05 YI, J. – RB05 YOKOJIMA, S. – FB06 YOO, H. S. – TD08 YOON, Y. – MF05, FA07 YU, P. – WA01

Z ZAIDI, Z. H. – MI07 ZALYUBOVSKY, S. J. – TF11 ZANNI, M. T. – MG02

ZHANG, L. – FA06 ZHANG, Y. – FC05 ZHANG, Z. – RH02 ZHENG, W. – MG05, MG06 ZOLLER, J. – TH06 ZWIER, T. S. – TG08, RB08, RB09, RB11 ¨ ZUCKERMAN, E. J. – TF06, TF07

The 16th International Conference on High Resolution Molecular Spectroscopy Prague, Czech Republic, September 3-7, 2000 The subjects covered at this meeting are largely identical to those covered at the Ohio State University Symposia on Molecular Spectroscopy. Information is available from the chairman of the local organizing committee, ˇ Dr. Vladim´ır Spirko Academy of Sciences of the Czech Republic J. Heyrovsk´y Institute of Physical Chemistry Dolejˇskova 3, CZ-18223 Praha 8, Czech Republic. Fax: +420 2 858 2307 E-mail: [email protected] or [email protected] WWW: http://www.chem.uni-wuppertal.de/conference/

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The 55th OSU International Symposium on Molecular Spectroscopy is pleased that the picnic expenses for students are subsidized by:

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Coffee and Doughnuts for the 55th OSU International Symposium on Molecular Spectroscopy Courtesy of:

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The Printing of the Proceedings for the 55th OSU International Symposium on Molecular Spectroscopy is Made Possible in Part by: Parker Hannifin Corporation The General Valve Operation