Flowing afterglow studies of formation and reactions of cluster ions of O2+, O2-, and O-

Abstract

The temperature-controlled flowing afterglow system has been utilized at temperatures below 300°K to measure the rate constants for the association of H2, N2, O2, CO2, N2O, and SO2 to O2+ with helium third body. Rate constants for the association of N2, O2, and CO 2 to O2- and for the association of N 2 and CO2 to O- have been measured at 200K. Some of the ion clusters formed in this way reacted via binary neutral interchange reactions of the type A±·B+C→A ±·C+B. Rate constants for these processes were obtained at and below 300K. The observation of these reactions allows an ordering of ion cluster bond energies. The increasing order of binding energies to O 2+ is H2, N2, O2, N 2O, SO2 and H2O. For the O2- ion clusters the increasing order is N2, O2, H2O, CO2, and NO. In some cases, equilibria are observed allowing a determination of binding energy differences. The three-body association rate constants increase with increasing binding energy of the ion cluster, in accord with theoretical expectation.