Symmetric charge transfer in low-energy ion-atom collisions

Abstract

Previous calculations of ion-atom interactions by the pseudopotential and asymptotic methods are used in the computation of the cross section for symmetric charge transfer at energies below 1 keV. The results for ${\mathrm{Li}}^{+}$, ${\mathrm{Na}}^{+}$, ${\mathrm{K}}^{+}$, ${\mathrm{Rb}}^{+}$, ${\mathrm{Cs}}^{+}$, and ${\mathrm{Ca}}^{+}$ ions are compared with data obtained in beam experiments, and by optical-pumping techniques. The difference in the cross sections for $^{2}P_{\frac{1}{2}}$ and $^{2}P_{\frac{3}{2}}$ ions of ${\mathrm{Kr}}^{+}$ and ${\mathrm{Xe}}^{+}$ at thermal energies is studied, and the predictions are compared with recent mobility measurements. Cross sections are obtained for ${\mathrm{U}}^{+}$-U collisions, and the dependence of the thermal cross section on the polarizability is described. Symmetric charge transfer of the negative ions ${\mathrm{H}}^{\ensuremath{-}}$, ${\mathrm{Na}}^{\ensuremath{-}}$, and ${\mathrm{Cs}}^{\ensuremath{-}}$ is discussed briefly.