DYNAMIC SCREENING OF IONS IN SOLIDS

The dynamic screening charge and potential induced by a charged partic le moving through or nearby condensed matter are central quantities re quired for an understanding of various phenomena; the pioneering ideas of Ritchie on dynamic screening have led the way to a great deal of t heoretical and experimental work on this topic. The asymmetry of the i nduced charge leads to a retarding force acting on the particle, i.e., stopping power. At high velocities, the collective response of the me dium manifests itself in an oscillatory trailing wake. The energy leve ls of the incoming ion, modified by the presence of the induced charge are important in the understanding of the resonant-coherent excitatio n effect at bulk and surfaces, charge states, and X-ray emission of in tra-atomic Auger transitions between levels of moving ions in solids. Recent results related to the above for different velocity regimes, bo th in linear and nonlinear theories, in bulk and surfaces, are discuss ed.