Partial ionisation cross sections for the binary-encounter Bethe model.

The original binary-encounter Bethe model of Kim and Rudd has proven to be an accurate analytical representation of total impact ionisation cross sections of electrons colliding with atoms and molecules. It is based on a decomposition into partial ionisation cross sections from electrons in bound orbitals. Despite the model’s accuracy for total ionisation, its individual cross sections for partial ionisation rely on thresholds calculated theoretically which systematically overestimate the experimental orbital binding energies. Here, we examine the model’s performance when based on experimental ionisation thresholds. The resulting partial cross sections of the various final (excited) ionic states produced could help to prefigure subsequent optical radiations and non-radiative transitions in models of plasma physics.