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 calculations, 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 bands of solid state targets, as opposed to their atomic states, is still missing. © 1995 The American Physical Society.