It is shown that the energy loss of multicharged ions in an electron gas ha
s 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 i
s found for L (or K) shells. Experiments on the charge state dependence of
the energy loss of multicharged N ions scattered under grazing incidence co
ndition off an Al(111) surface are explained consistently by our model.