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Fluorescence quantum yields and radiative and nonradiative lifetimes of glyoxal (/sup 1/A/sub u/)

Journal Article · · J. Chem. Phys.; (United States)
OSTI ID:5699339
Fluorescence quantum yields (Phi/sub F/) from single vibronic levels (SVL's) of glyoxal have been measured between 1 and 12 mTorr. The zero-pressure extrapolated values of Phi/sub F/ decrease nearly monotonically from 0.58 for the zeroth vibrational level (0/sup 0/) to 0.22 for the 2/sup 1/8/sup 1/ level at E/sub vib/=2126 cm/sup -1/. From our values of Phi/sub F/ and the fluorescence decay times (tau/sub F/) measured earlier by Beyer, Zittel, and Lineberger (BZL), the collision-free values of radiative (tau/sub R/) and nonradiative (tau/sub NR/) lifetimes have been obtained. The observed value of tau/sub R/ for the 0/sup 0/ level is 4.1 ..mu..sec, as compared to the calculated value of 15 ..mu..sec estimated from integrated absorption by BZL. Since the observed values of Phi/sub F/ are considerably greater than what had been estimated earlier, the new values for the nonradiative rate (k/sub NR/) are correspondingly smaller. The out-of-plane deformation mode (..nu..'/sub 8/) is most effective as an inducing and promoting mode.
Research Organization:
Department of Chemistry, University of California, Irvine, California 92717
OSTI ID:
5699339
Journal Information:
J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 71:12; ISSN JCPSA
Country of Publication:
United States
Language:
English