Temperature Dependence of the Electron—O2+-Ion Recombination Coefficient

The temperature dependence of the coefficient for the recombination of electrons with mass-identified ${\mathrm{O}}_2^{+}$ ions has been determined from observations of the electron and ion decay rates in the afterglow following "single-pulse" microwave discharges in ${\mathrm{O}}_2$-Ne, ${\mathrm{O}}_2$-Ne-Ar, and ${\mathrm{O}}_2$-Ne-Kr gas mixtures. Temporal mass analysis, utilizing multichannel signal-averaging techniques, shows similar decay rates for the electrons and for the ${\mathrm{O}}_2^{+}$ ions over the major portion of the afterglow. The observed recombination coefficient, $\alpha \left({{\mathrm{O}}_2}^{+}\right)$, has a temperature dependence approximated by ${T_{\mathrm{gas}}}^{-1\mathrm{}}$, the values at temperatures of 205, 295, and 690°K being (3.0±0.3)×${10}^{-7\mathrm{}}$, (2.2±0.2)×${10}^{-7\mathrm{}}$, and (1.0±0.2)×${10}^{-7\mathrm{}}$ ${\mathrm{cm}}^3$/sec, respectively. At the lower temperatures the dimer ion ${\mathrm{O}}_2$ · ${\mathrm{O}}_2^{+}$ becomes significantly more important. Analysis of the data yields a coefficient of approximately 2.3 × ${10}^{-6\mathrm{}}$ ${\mathrm{cm}}^3$/sec for the recombination of this ion with electrons at a temperature of 205°K.