Picosecond CO/sub 2/ laser interactions with polyatomic molecules: Progress report, July 15, 1986-July 14, 1988

Technical Report · Wed Feb 10 04:00:00 EST 1988

OSTI ID:7159633

Kwok, H S

During the past two years of this research program, significant advances have been made on the understanding of the process of intramolecular energy redistribution (IVR) in the vibrational quasicontinuum of polyatomic molecules. Two approaches for this experimental program were employed. They were IR-IR double resonance absorption spectroscopy and vis-IR multiphoton ionization spectroscopy. In both cases, significant results were obtained. In particular, it was found that the collisionless IR absorption spectra of vibrationally excited molecules are dependent on the probe pulse duration. For very short 20 ps pulse, the absorption spectra have very clean Lorentzian lineshapes with zero absorption away from the line center. For longer pulses, the entire spectra broaden and a constant background absorption emerges. This result indicates that the absorption is confined to narrow line for short times, and other lines contribute to absorption at longer interaction times. It implies that nonstatistical or even mode selective chemistry is possible on these short timescales. Using multiphoton ionization spectroscopy it was found that the strong coupling of the ground electronic state and the first excited electronic state resulted in ultrafast internal energy conversion in CrO/sub 2/C/ell//sub 2/. By selectively pumping different vibrational lines in the excited state, a rapidly increasing coupling was measured as the vibrational quantum number increased. This new class of experiment is different from our previous ps CO/sub 2/ laser pulse experiments in the sense that state-state specific energy relaxation is studied. 4 figs.

• Research Organization: State Univ. of New York, Buffalo (USA). Dept. of Electrical and Computer Engineering
• DOE Contract Number: FG02-85ER13405
• OSTI ID: 7159633
• Report Number(s): DOE/ER/13405-3; ON: DE88013822
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
ABSORPTION SPECTROSCOPY
CARBON DIOXIDE LASERS
COLLISIONS
CROSS SECTIONS
DOCUMENT TYPES
ENERGY LEVELS
EXCITED STATES
GAS LASERS
INFRARED SPECTRA
IONIZATION
LASER SPECTROSCOPY
LASERS
LINE BROADENING
MOLECULES
MULTI-PHOTON PROCESSES
PHOTOIONIZATION
POLYATOMIC MOLECULES
PROGRESS REPORT
SPECTRA
SPECTROSCOPY
TIME DEPENDENCE
VIBRATIONAL STATES