He2+-He collisions: one-electron capture versus electron removal and target-ion excitation

The authors have studied electronic redistribution processes, associated with production of excited He + ions, in He 2+ -He collisions at energies ranging from 1 to 300 keV amu -1 . Excited He + ionic states can be formed (i) in the projectile by one-electron transfer, and (ii) in the target by removing one of the target electrons and simultaneously exciting the residual ion. At the highest energies between approximately 10 and 60 keV amu -1 the first process is the most important one. However, for low energies below 10 keV amu -1 they obtain the striking result that both processes are equally likely.