Ionization of highly charged ions by electron impact

Abstract

Scaled cross sections Z⁴Q are calculated for ionization from the 1s, 2s and 2p sublevels of hydrogenic ions with Z= infinity using the Born exchange, or equivalently the Coulomb-Born-Oppenheimer approximation, which is exact, apart from relativistic corrections, in this limit. These results together with results of Rudge et al. (1966) for Z=128 are fitted to an analytic expression that goes into the correct Bethe approximation results of Omidvar (1969) for high energies. A prescription is given for obtaining approximate ionization cross sections and rates for highly charged complex ions of finite Z from the hydrogenic ion results for Z= infinity .