Relaxation in the 1A u state of glyoxal. II. Collisional quenching

Cross sections are reported for collisional quenching of low-lying levels of the 1Au state of glyoxal by 24 collision partners at 297 °K. The quenching cross sections varied from 1 to 22 Å2 with polar collision partners exhibiting the larger cross sections. The quenching rate constants were determined by measuring the time-resolved decay of laser-excited glyoxal, as a function of quench gas pressure. Studies of 3Au state production for five of these gases indicate that the principal collisional loss channel from the 1Au state is to the 3Au state. The derived quenching cross sections are well parameterized by several differing quenching models, not all of which should be valid in this case; such correlations have predictive value, but cannot be taken to verify the quenching model.