Competition between dissociative and nondissociative single-electron capture inHe2+−O2collisions

Abstract

State-selective single-electron capture in slow collisions of He 2 + ions with O 2 has been studied experimentally at laboratory impact energies between 0.1 and 1.0 keV by means of the translational energy-gain spectroscopy technique. The translational energy spectrum clearly shows that the dominant reaction channel is due to dissociative single-electron capture [single-electron capture into He + (n=1) with target ionization, i.e., transfer ionization] at low energies, whereas contributions from capture into the He + (n=2) state with the production of O 2 + in the ground state (X 2 Π g ) (nondissociative single-electron capture) increase as the collision energy is increased and becomes the dominant process at collision energies E≥0.7 keV. The energy dependence of total cross sections for single-electron capture is also measured and found to slowly increase with increasing collision energies.