The electron impact single ionization cross sections on a number of targets with atomic number Z=1-92 in the H and Li isoelectronic sequences are calculated using a modified version of the recently propounded relativisitic improved binary-encounter dipole (MRIBED) model [M. A. Uddin , Phys. Rev. A 70, 032706 (2004); 71, 032715 (2005)]. The modified RQIBED (MRIBED) model along with a Z-dependent factor in it is found remarkably successful in the applications to H- and Li-like systems and also valid for the ionization of a filled s orbit including the He-like targets.
Uddin, M A.; Haque, Abul Kalam fazlul; Basak, A K.; Karim, Khondkar R.; and Saha, B C., "Electron-impact ionization of hydrogen and lithiumlike systems" (2005). Faculty publications – Physics. Paper 26.