Classical electron ionization cross sections

The cross section for electron ionization of the first five excited states of hydrogen are calculated using Gryzinski's classical theory. These cross sections are compared with cross sections calculated using the first Born approximation. The classical cross sections are in good agreement with the quantal cross sections except at very large impact energies where the classical cross sections do not have the correct fall-off. If the correct fall-off is added to the classical cross sections, these cross sections differ only slightly from the Born cross sections at high impact energies.