Separability of Intra- and Intermolecular Vibrational Relaxation Processes in the S1 State of trans-Stilbene

Autor:	Jun Qian, S. L. Schultz, John M. Jean
Rok vydání:	1997
Předmět:	education.field_of_study Internal energy Chemistry Intermolecular force Population Non-equilibrium thermodynamics Molecular physics Thermalisation Excited state Vibrational energy relaxation Redistribution (chemistry) Physics::Chemical Physics Physical and Theoretical Chemistry education
Zdroj:	The Journal of Physical Chemistry A. 101:1000-1006
ISSN:	1520-5215 1089-5639
DOI:	10.1021/jp962454h
Popis:	Detailed time-resolved measurements of anti-Stokes intensities of several high-frequency modes of electronically excited trans-stilbene in hexane and methanol are reported. The most striking changes are observed in the ethylenic band at 1570 cm-1. Nonequilibrium population in the v = 1 level of this mode is found to exhibit a biphasic decay, which is interpreted as a rapid energy redistribution followed by a slightly slower process that reflects the transfer of excess energy to the solvent. Comparison of the time-dependent intensity changes of several high-frequency bands with those from a model that assumes instantaneous thermalization of the excited state suggests that internal energy randomization is incomplete on the time scale of solute−solvent thermal equilibration process. No evidence of mode specificity in the energy redistribution process is observed. The results show us to place a value of ∼2 ps on the lifetime of the v = 1 level of the ethylenic stretching mode of trans-stilbene in both hexane ...
Databáze:	OpenAIRE
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