Impact parameter dependence of electronic and nuclear energy loss of swift ions:: H+ → He and H+ → H

In this paper we report the calculation of impact parameter dependent energy losses of protons on hydrogen and helium for projectile energies from a few eV/amu up to 900 keV/amu using electron-nuclear dynamics (END). In each case it is found that, for smaller impact parameters, there is an initial rise in energy deposition at low projectile energies due to nuclear stopping. At somewhat larger energies, the nuclear contribution decreases, and the energy loss is primarily due to electronic stopping. As the ionization channel is not explicitly open in these calculations, these results are somewhat below experimental results at energies above the ionization threshold. Agreement with other calculations and the scanty experimental evidence is good. (C) 2000 Published by Elsevier Science B.V. All rights reserved.