Electronic stopping of heavy ions in the Kaneko model

The familiar results of effective charge theory of the electronic stopping of heavy ions in solids have hitherto been based on the target model of a homogeneous electron gas. The `heavy ion scaling rule' and experimental proton data were used to incorporate the major information on the polarization of real target materials. Introducing Kaneko's generalized target dielectric functions provides a description of the physical processes from a more ab initio point of view. We propose three refinements of his theory to explain heavy ion stopping data: (i) a correction to introduce band gaps in the target susceptibilities, (ii) a model to exclude the target polarization nearby the ion nucleus from the calculation, and (iii) generalized susceptibilities of target p and d shells. A final discussion points out that the mutual screening of free and d electrons in transition metal targets is most pronounced for light ion stopping powers, but that a wishful special treatment of electrons in d ban..