MULTIPLE-ELECTRON IONIZATION, CAPTURE, AND LOSS BY 19-MEV F-Q+ (Q=2-9) IN COLLISIONS WITH NE AND AR

Charge-exchange processes in fast collisions of F-q+ (q=2-9) on Ne and Ar gas targets have been studied using the projectile-recoil-ion coincidence method. The target ionization without a projectile charge change increases with increasing projectile charge approximately as similar to q(1.4). This dependence is weaker than the q(2) dependence predicted by the first Born approximation because of the large ionization probabilities involved. The single-electron-capture cross sections follow the known q(3) scaling law while the double-electron-capture cross sections display a q(6) dependence, as predicted by the independent-electron approximation for small capture probabilities. Single- and double-electron loss from the L shell decreases with increasing q mainly because of the decrease in the number of L-shell electrons, while binding-energy effects play only a minor role. In contrast, the large sudden decrease in electron-loss cross sections once K-shell electrons must be removed is due to the large increase in binding energy.