Distorted-wave cross sections for electron-impact ionization of Ar⁷⁺

Distorted-wave methods have been used to calculate cross sections for electron-impact ionization of sodiumlike Ar⁷⁺ for collision energies ranging from near threshold to 1 keV. We included contributions due to excitation-autoionization and resonant excitation–double autoionization (REDA), as well as the contributions from direct ionization of the 3s electron and the n=2 inner-shell electrons. We find that the effects of radiative damping and loss channels reduce the REDA contributions by a factor of 4. We compare our calculated results to experimental results and to theoretical cross sections obtained in a close-coupling approximation. © 1996 The American Physical Society.