Hot atom-laser induced fluorescence experiments on the reaction of H(2S) with O2

Abstract

A method has been developed to study the dynamics of reactions with substantial threshold energies by combining hot atom production by laser photolysis and fast product detection by laser induced fluorescence. The nascent OH rotational, vibrational, and fine structure state distributions produced in the endothermic reaction H+O2→OH(K,v, f )+O have been measured with hot hydrogen atoms from the photodissociation of HBr at 193 nm. OH rotational excitation is high and corresponds to the phase space statistical distribution over the measured range of rotational states. Also OH vibrational excitation is substantial. The OH spin doublets are produced statistically, but the partitioning in the λ doublets is very nonstatistical with a strong preference for the π+ component demonstrating the reaction to occur essentially in a plane at high collision energies. By measuring reactant and product densities at short times, an absolute total cross section of 0.42±0.40.2 (Å2) has been obtained.