Electron-impact single ionization cross sections of helium isoelectronic systems

The cross sections for electron-impact single ionization of helium-like targets,—Li⁺, B³⁺, C⁴⁺, N⁵⁺, O⁶⁺, Ne⁸⁺, Na⁹⁺, Fe²⁴⁺, Ag⁴⁵⁺, and U⁹⁰⁺—are calculated using a recently propounded parameter-free relativistic binary encounter (RBEA) model, which remains valid up to the relativistic energy domain. Our RBEA results are compared with those of the Coulomb–Born (CB) approximation, distorted wave Born approximation (DWBA), relativistic two-potential DWBA (RTPD), the simple empirical model of Brenshtam et al. (BRY), and the model of Deutsch and Märk (DM) along with the available experimental data. The RBEA model, while keeping the comparable predictive power of cross sections, is found to overcome the limitations of the empirical BRY and DM models with their fitting parameters, and the quantum mechanical CB, DWBA, and RTPD theories with arduous and lengthy calculations. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004