title: Quantum statistical study of O + O2 isotopic exchange reactions: cross sections and rate constants.
abstract: Using a wave packet based statistical model, we compute cross sections and thermal rate constants for various isotopic variants of the O + O2 exchange reaction on a recently modified ab initio potential energy surface. The calculation predicts a highly excited rotational distribution and relatively cold vibrational distribution for the diatomic product. A small but important threshold effect was identified for the (16)O + 18O2 reaction, which is suggested to contribute to the experimentally observed negative temperature dependence of the rate ratio, k(18O + 16O2)/k(16O + 18O2). Despite reasonable agreement with quasiclassical trajectory results, however, the calculated thermal rate constants are smaller than experimental measurements by a factor from 2 to 5. The experimentally observed negative temperature dependence of the rate constants is not reproduced. Possible reasons for the theory-experiment discrepancies are discussed.
authors.affiliation: Department of Chemistry, University of New Mexico, Albuquerque, New Mexico 87131, USA.
authors.forename: Shi Ying
authors.initials: SY
authors.lastname: Lin
authors.forename: Hua
authors.initials: H
authors.lastname: Guo