Importance of dissociative excitation by slow He2+ ions in one-electron capture collisions with H2

Abstract

Translational energy spectroscopy has been used to study one-electron capture by 0.5-2.0 keV amu-1 He2+ ions in collision with H2. The main excited state product channels have been identified and the relative cross sections determined. These measurements provide the first direct evidence of the relative importance of dissociative excitation channels in electron capture (with He+ formed in the ground state and H atoms mainly in the n=2 states) which dominate the entire energy range. Non-dissociative electron capture into the n=2 and n=3 states of He+, which is also observed, increases from 1% of the total electron capture cross section at 0.5 keV amu-1 to about 25% at 2 keV amu-1.