O(3P) atom lifetimes and mobilities in xenon matrices

The concentration of O atoms in xenon matrices at 32 and 40 K is followed by monitoring 736 nm emission from XeO* excimers. Emission is induced by excitation of O atom Xe pairs with 193 or 248 nm radiation. O atoms are initially produced via UV photolysis of N2O. At 32 K, approximately 50% of the atoms present after the initial probe pulse persist after eight days. The most likely mechanism for O atom decay is O+O recombination. At both temperatures, the time dependence of the concentration of O atom decay cannot be fit to a single bimolecular decay. It can, however, be fit to two (or more) bimolecular decays. Based on this mechanism, diffusion coefficients for the longer time scale diffusion process are 5.4×10−18 and 2.0×10−17 cm2/s at 32 and 40 K, respectively. Other possible explanations for the observed O atom time dependence are discussed.