REACTION OF O(1D) WITH ETHYLENE - VIBRATIONAL AND ROTATIONAL STATE DISTRIBUTION OF PRODUCT OH

Reaction of O(1D) with ethylene was studied under low pressure flow conditions. The O(1D) was formed by photodissociation of N2O by an ArF laser and rotational and vibrational state distributions of product OH were determined by laser induced fluorescence. The rotational distributions of the v = 0 and 1 levels showed a bimodal feature. A major part of the OH had a rotational energy higher than the statistical expectation, and about 20% of total available energy appeared as the rotation of OH. About 20% of the total OH was characterized by a rotational distribution that corresponded to a specific temperature, i.e., 546 K and 526 K for v=0 and 1, respectively. The relative populations of the first two vibrational levels were measured to be 1.00 and 0.30, and no inversion was observed. No propensity was observed between formation of the two spin-orbit states, and the PI(A') state was slightly more favored than the PI(A'') state. These results were explained by a mechanism in which O(1D) inserts into a CH bond of ethylene and OH is eliminated from a bend geometry. The same reaction was studied under cluster conditions where a van der Waals complex of N2O-C2H4 Was converted into the reactant pair, O(1D)-C2H4. The rotational distribution of OH formed under these conditions showed little difference from that from the bimolecular reactions.