Ionization of H(2s) and H(2p) by electron impact

The electron impact ionization cross section of H(2s) and H(2p) in the Born A, Born B, Born-Ochkur and classical approximations are reported together with those of H(2s) in the Born exchange approximations. Calculations cover a range of impact energies from 4.87 eV to 300 eV. The Born-Ochkur approximation results in considerable reduction of the cross section in the low energy region. There is close accord between the Born exchange cross section corresponding to maximum interference and the Born-Ochkur cross section for the ionization of H(2s).