TEMPERATURE AND KINETIC-ENERGY DEPENDENCES OF THE RATE-CONSTANT FOR THE REACTION OF O- WITH SO2

Rate constants for the reaction of O- with SO2 have been measured as a function of ion-neutral average center-of-mass kinetic energy (〈KEcm〉) at each of three temperatures: 203, 295, and 489 K. The temperature dependence of the rate constant is reported here for the first time and is of the form T-0.27. The energy dependence data are in excellent agreement with a published study and show the overall rate constant decreasing with increasing 〈KEcm〉. The energy dependences measured at the different temperatures all lie on one curve, which suggests that the rate constant is independent of the internal temperature of the SO2 neutral at a given collision energy. The branching ratio between associative detachment and charge transfer was also measured as a function of 〈KEcm〉 at the three temperatures. An activation energy of 0.3 eV for the endothermic charge-transfer channel has been derived from the energy dependence of the rate constant for charge transfer. © 1990 American Chemical Society.