ELECTRONIC-ENERGY LOSS AND EFFECTIVE CHARGE OF HEAVY-IONS IN DIFFERENT TARGETS

The process of stopping is conveniently described in two steps. The fi rst step is the dynamic screening of the impacting projectile by the e lectron gas of the target which results in the concept of effective ch arge. The second is the interaction between the screened projectile an d the target atoms. A model of an impacting heavy ion embedded in a je llium is used to calculate the static charge state and the effective c harge of the heavy ion at the zero velocity limit based on the self-co nsistent density-functional theory. This effective charge of the heavy ion at low velocities is extrapolated to a higher velocity by means o f the BK formula. The quantal harmonic oscillator model which takes th e structures of target atoms into accounts is generalized to calculate the electronic energy loss of heavy ions colliding with three kinds o f targets. The results are compared with the available experimental da ta. (C) 1998 Elsevier Science B.V.