Electron impact ionization of complex ions

Abstract

The simple procedure suggested by Burgess et al. to allow for inner-shell excitation and auto-ionization has been used with an empirical formula of similar form to that of Lotz and compared with a wide range of crossed-beam experimental data for ions of charge z ≽ 2. The resulting simple general formula for the total ionization cross-section, and the corresponding rate coefficient, represents the experimental data to within ±23 per cent rms deviation. The formula is consistent with the earlier formulae of Seaton (valid only near threshold) and of Lotz, but 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 satisfactory. Comparisons are also made with the simplified ECIP formula.