Low-energy collisions of O5+ ions with He atoms: Single-electron capture, projectile excitation, and transfer excitation and ionization.

Abstract

A theoretical study of various inelastic processes resulting from collisions of ${\mathrm{O}}^{5+}$ ions with He atoms is carried out by a semiclassical molecular-orbital expansion method with the inclusion of electron translation factors at collision energies of 60 eV/u to 15 keV/u. In addition to the single-electron-capture process, projectile excitation and transfer excitation and ionization processes are also studied, and the corresponding cross sections are determined. Dominant processes are found to be a single-electron capture to the ${\mathrm{O}}^{4+}$(2s3s) and ${\mathrm{O}}^{4+}$(2s3p) states. Other channels are found to make weak but non-negligible contributions. All processes proceed on the outgoing part of the collision, after the transitions from the initial channel to the single-electron-capture channels are completed. Hence, direct processes to projectile excitation and transfer excitation are nearly negligible. The agreement of the present calculation for single-electron capture with measurements is very good.