He2+-H2collisions: non-dissociative and dissociative one-electron capture

Electron-redistribution processes in collisions of He 2+ ions on H 2 are studied for energies from 1 to 25 keV amu -1 . One-electron capture and target excitation cross sections are determined by photon-emission spectroscopy. At energies exceeding approximately 5 keV amu -1 capture into excited states is the dominant charge-transfer process while at lower energies one-electron capture into the ground state dominates. The latter process is found to be accompanied by dissociation of the target and excitation of the resulting hydrogen atom. This can be explained qualitatively with the classical overbarrier model under the assumption that during the collision binding energy is exchanged between the electrons, which is a kind of auto-excitation process.