Key points are not available for this paper at this time.
Electron-impact-ionization cross sections have been measured for the halogen atoms F, Cl, Br, and I from threshold to 200 eV. The absolute accuracy is 14%, except for F which is 20%. The halogen cross sections have shapes similar to those of the neighboring rare gases but are greater in magnitude. Simple semiclassical formulas of electron-impact ionization are able to accurately predict the experimentally determined halogen to rare gas cross-section ratios.
Hayes et al. (Thu,) studied this question.