VIBRATIONAL-STATE SPECIFICITY AND SELECTIVITY IN THE REACTIONS N+OH-]NO(V)+H AND N+NO(V)-]N2+O

The vibrational state distribution of NO formed in the radical-radical reaction N + OH --> NO(v' less-than-or-equal-to 9) + H; DELTAH0(0)= -204.0 kJ mol-1 has been determined using a pulse-and-probe technique. OH radicals were generated by pulsed laser photolysis of H2O2 at 266 nm in a flow of N2 which had been passed through a microwave discharge to produce N atoms. The vibrational distribution of NO, measured by laser-induced fluorescence (LIF) spectroscopy, is similar to that predicted by phase-space theory and corresponds to an average yield of ca. 31% of the energy available to the reaction products. Experiments in which LIF signals were observed as the pulse-probe time delay was varied showed that populations within different vibrational levels (v=0-8) displayed similar kinetics, consistent with rapid removal of NO(v) by reaction with N atoms, N + NO(v) --> N2 + O, at rates which exhibit a mild dependence on v.