Energy transfer in the 1Austate of glyoxal. III. Deuterium effects

Abstract

Collision-free lifetimes and collisional quenching rate constants are reported for a number of single vibrational levels of glyoxal-d2 (1Au) and glyoxal-hd (1A″) and are compared with previous results for glyoxal-h2. There was some success in correlating the dependences of collision-free decay rates on specific vibrational level and on isotopic substitution with the predictions of intramolecular, nonradiative decay theory. There are strong isotope effects on the collision-free lifetimes, but the rate constants for collision depopulation of a vibronic level, which increase sharply with energy in the excited state, are strikingly isotope independent. The increase is believed to be primarily a result of increased intersystem crossing rate and is compared with a mixed state model proposed by Freed.