It is shown that the energy loss of multicharged ions in an electron gas has a strong dependence on target electronic screening and the occupation of projectile levels. In our calculations, an enhancement (or decrease) of the energy loss as it depends on the number of vacancies in the inner shells is found for $L$ (or $K$) shells. Experiments on the charge state dependence of the energy loss of multicharged N ions scattered under grazing incidence condition off an Al(111) surface are explained consistently by our model.

• Received 25 September 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.1048