DYNAMICS OF CO FORMATION IN THE REACTION O(P-3)+C2H3

The internal state distributions of CO(tau, J) formed in the reaction of oxygen atoms with vinyl radicals were measured using an arrested re laxation FTIR apparatus. In spite of the deep potential energy minimum corresponding to vinery radical, the expected intermediate in the rea ction, the CO is born with a strongly non-statistical vibrational dist ribution. Ab initio calculations on the important stationary points of the C2H3O potential energy hypersurface provide some insight into the reaction dynamics. In particular, the barrier for I-I-atom migration in the process: vinery --> acetyl, is calculated to be 42 kcal mol(-1) above the vinery potential minimum; this lies some 80 kcal mol(-1) be low the reagent energy. Since this is the only substantial barrier on the reactive potential surface, the dynamics of the reaction are bette r described as following a direct, rather than a complex-forming mecha nism.