Calculated absolute cross-sections for the electron-impact ionization of atoms with atomic numbers between 20 and 56 using the Deutsch-Märk (DM) formalism

We report results of the calculation of electron-impact ionization cross-sections for atoms with atomic numbers Z in the intermediate range of Z-values (20 < Z < 56) using the DM formalism. For atoms with Z-values in this range (which contains many atoms of practical importance), there are some experimentally determined ionization cross-sections, but there has only been a single systematic theoretical study from 30 years ago, which was based on the Born approximation. The Born approximation tends to yield cross-sections which show an "overestimation" in the energy regime of the cross-section maximum compared to experimental data. The DM approach, on the other hand, has adequately reproduced the region of the cross-section maximum for many low-Z atoms as well as for the heavier rare gases. In the present case of atoms with Z-values from 20 to 56, the DM calculation typically shows a cross-section maximum lower than that predicted from the Born approximation by 25-50%, except for Xe, Ni, Cd, and Pd. The Born approximation and the DM formalism yield cross-sections that converge at higher impact energies.