Intramolecular vibrational relaxation in aryl alkyl ketones as revealed by excess energy dependence of T/sub 1/. -->. S/sub 0/ intersystem crossing rate

Journal Article · Wed Oct 15 00:00:00 EDT 1980 · J. Chem. Phys.; (United States)

OSTI ID:5002451

Hirata, Y; Lim, E C

T/sub 1/(n..pi..*)..-->..S/sub 0/ intersystem crossing in dilute vapors of aryl alkyl ketones has been studied as a function of excess vibrational energy (in T/sub 1/) to determine the relative efficiency of intramolecular vibrational energy redistribution. The excess energy dependence of the nonradiative decay rate, as measured by ..cap alpha..=d ln k/dE, is strongly molecular structure dependent. Molecules with a large alkyl group exhibit very large ..cap alpha.. for S/sub 0/..-->..S/sub 1/(n..pi..*) excitation and relatively small ..cap alpha.. for S/sub 0/..-->..S/sub 2/(..pi pi..*) excitation. Molecules with a small alkyl group (acetophenone) exhibit an intermediate value of ..cap alpha.., which is independent of the mode of excitation. These results indicate that the rate and the extent of communication between carbonyl and ring vibrations are significantly smaller for molecules with a bulky alkyl group. The possible origin of this ''size-dependent'' vibrational relaxation is discussed.

• Research Organization: Department of Chemistry, Wayne State University, Detroit, Michigan 48202
• OSTI ID: 5002451
• Journal Information: J. Chem. Phys.; (United States), Vol. 73:8
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
KETONES
ABSORPTION SPECTRA
ENERGY-LEVEL TRANSITIONS
ENERGY DEPENDENCE
RELAXATION
VIBRATIONAL STATES
ENERGY LEVELS
EXCITED STATES
ORGANIC COMPOUNDS
SPECTRA
640302* - Atomic
Molecular & Chemical Physics- Atomic & Molecular Properties & Theory