Ion-Ion Mutual Neutralization Cross Sections Measured by a Superimposed Beam Technique. II. O2+ + O2−, O2+ + NO2−, and NO+ + NO2−

Abstract

Two-body ion-ion neutralization cross sections $Q$ have been measured for ${\mathrm{NO}}^{+}$ + ${\mathrm{NO}}_2^{-}$ and ${\mathrm{O}}_2^{+}$ + ${\mathrm{NO}}_2^{-}$ and remeasured for ${\mathrm{O}}_2^{+}$ + ${\mathrm{O}}_2^{-}$. Using a superimposed-beams method, a range of barycentric energies between 0. 15 and 200 eV was covered. The product $v_{r}Q$ behaved somewhat similarly for all reactants when plotted against the relative speed $v_r$. For relative energies above 3 eV, $v_{r}Q$ varies slowly and is of a magnitude of ${10}^{-7\mathrm{}}$ ${\mathrm{cm}}^3$/sec or greater. Below about 3 eV, however, $v_{r}Q$ begins to increase rather rapidly with decreasing energy, approaching the expected $v_r^{-1\mathrm{}}$ dependence. The low-energy data have been fitted to four-term polynomials in powers of $v_r$. In this form the data can be extrapolated to the thermal range and rate constants obtained. Reaction rates (300 °K) are given for the above reactants, and also for ${\mathrm{H}}^{+}$ + ${\mathrm{H}}^{-}$, ${\mathrm{O}}^{+}$ + ${\mathrm{O}}^{-}$, ${\mathrm{N}}^{+}$ + ${\mathrm{O}}^{-}$, and ${\mathrm{N}}_2^{+}$ + ${\mathrm{O}}_2^{-}$, which were studied earlier.