Single and double ionization of lead by electron impact

Abstract.

Theoretical calculations of electron impact single and double ionization cross-sections for ground state lead atoms have been performed in the binary encounter approximation (BEA) in the energy region ranging from respective near thresholds to 3000 eV. The accurate expression for $\sigma_{\Delta E}$ (cross-section for energy transfer $\Delta E)$ including exchange and interference as given by Vriens and Hartree-Fock velocity distributions for the target electrons have been used throughout the calculations. It is concluded that beyond 10.64 eV impact energy single ionization cross-sections are well explained by considering ionization of 6p and 6s shells only. The direct double ionization cross-sections obtained theoretically cannot explain the recent experimental observations. Inclusion of contributions of the Auger effect due to vacancy in 5d and 5p shells brings the results of double ionization cross-sections in reasonably good agreement with the experimental data. The identification of the shells whose ionization leads to the Auger effect contributing to double ionization is a remarkable aspect of the present investigation.