Electron impact ionization of complex ions

Abstract

The procedure suggested by Burgess et al. (1977) to allow for inner-shell excitation and auto-ionization is used with an empirical formula similar in form to that of Lotz (1968) and is compared with a wide range of crossed-beam experimental data for ions having a charge greater than or equal to 2. The general formula obtained for the total ionization cross section, and the corresponding rate coefficient, represents the experimental data to within + or - 23 percent rms deviation. Even though the formula is consistent with the earlier formulas of Seaton (1964, valid only near threshold) and Lotz, it gives a significantly smaller rms deviation through the consistent inclusion of auto-ionization effects. For simple ions, comparisons with much more elaborate quantal calculations are found to be satisfactory. In addition, comparisons are made with the simplified ECIP formula (Burgess, 1964; Burgess and Summers, 1976).