Electron Detachment in Collisions of O−, OH−, and O2− Ions with Rare-Gas Atoms

Abstract

Total cross sections for the electron detachment process ${\mathrm{X}}^{-}\mathrm{\hspace{0.17em}+\hspace{0.17em}}\mathrm{Y}{\mathrm{\hspace{0.17em}=\hspace{0.17em}e}}^{-}\mathrm{\hspace{0.17em}+\hspace{0.17em}}\mathrm{X}\mathrm{\hspace{0.17em}+\hspace{0.17em}}\mathrm{Y}$ have been measured for the collision systems O⁻–He, O⁻–Ne, O⁻–Ar, O₂⁻–He, and OH⁻–He, in ion‐beam gas‐scattering experiments which extend from primary ion energies of 400 eV down to several electron volts. Detached electrons were separated from other negative reaction products either by a radio‐frequency electron filter, or by electrostatic‐retardation analysis. Particular emphasis was placed on the low‐energy region near detachment threshold; the data obtained in this region was found to conform fairly well to predictions of theoretical threshold laws. The cross sections obtained at higher energies are, for the most part, in good agreement with previous measurements.