Vibronic activity probed by laser jet spectroscopy

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:5585317

Warren, J A

Laser jet spectroscopy is applied to study the vibronic activity in ..beta..-methylnaphthalene and phenanthrene. Results of these studies indicate that the technique is invaluable in the determination of the mechanisms and spectral manifestations of vibronic coupling in large polyatomic species. In the S/sub 1/ state of ..beta..-methylnaphthalene, a Duschinsky rotation of normal coordinates results in extensive mode mixing as evidenced by highly structured single vibronic level (SVL) fluorescence spectra and drastic absorption/fluorescence mirror symmetry breakdown (MSB). The rotation is shown to be well modeled by simple first order perturbation formulae which readily reproduce the observed spectra. Additionally, anharmonicities to fourth order are apparent from the spectra of the molecule. In phenanthrene, absorption/fluorescence MSB is shown to be primarily the result of Condon/Herzberg-Teller transition moment interferences and model calculations again indicate that simple first order formulae can be used to reduce the observed spectra. While mode mixing does not appear to be important for totally symmetric modes of the molecule, vibronically induced transition of b/sub 2/ symmetry clearly indicate mixing from a Duschinsky rotation in these normal modes. Mixing as a result of Fermi resonances is also observed for some levels.

• Research Organization: Iowa State Univ. of Science and Technology, Ames (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5585317
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AROMATICS
CONDENSED AROMATICS
ENERGY LEVELS
EXCITED STATES
HYDROCARBONS
JETS
LASER SPECTROSCOPY
NAPHTHALENE
ORGANIC COMPOUNDS
PHENANTHRENE
SPECTROSCOPY
VIBRATIONAL STATES