Ab initio studies of the reaction of O(P-3) with CHClF radical

The reaction of oxygen atom with chlorofluoromethyl radical has been studie d extensively using the G2(MP2) level of theory. The computation reveals an association-elimination mechanism. The addition reaction of O(P-3) with CH ClF proceeds to the formation of an energy-rich intermediate CHClFO*. Five product channels of CHClFO* are found: Cl + CHFO, H + CClFO, CClFOH, HF + C lCO, and F + CHClO. The isomer CClFOH can decompose through six product cha nnels: H + CClFO, HCl + FCO, HF + ClCO, Cl + FCOH, F + ClCOH, and OH + CFCl ((1)A'). On the basis of this ab initio potential energy surface, the ener gy-specific rate constants of the unimolecular decomposition of the activat ed adduct CHClFO* are used to estimate the branching ratio with RRKM theory . The productions of Cl + CHFO and H + CClFO are shown to be the dominant a nd competitive reaction channels. The implications of our results are discu ssed in terms of understanding the atmospheric and combustion chemistry of the CHClF radicals.