Luminescence and triplet decay in quinoxaline vapors

The effects of the gas pressure on the quinoxaline triplet state kinetics and luminescence yields were studied in the 10^?3 ?10 torr pressure range. The non-exponential character of the fluorescence decay and long fluorescence lifetimes, previously reported, are confirmed. The collision-free lifetime of the “hot” triplet state measured by triplet—triplet absorption kinetics and by phosphorescence collisional induction is of the order of 100 μs, much longer than the long-fluorescence decay times (0.5–70 μs). The results are discussed on the basis of a model involving anharmonic coupling between triplet levels strongly and weakly coupled to the singlet.