Electron impact double ionization of Fe

Electron impact double ionization cross-sections for Fe+ and Fe3+ have been calculated in the modified binary encounter model incorporating the effects of the Coulombic field of the target on the incident electron. Accurate expression of cross-section for energy transfer $\Delta E$ given by Vriens and Hartree-Fock velocity distributions for the target electrons have been used throughout the calculations. The present results show satisfactory agreement with experimental observations. It is concluded that the discrepancy in the high energy region observed in the present calculations may be attributed to non-inclusion of indirect ionization processes arising from the L-shell