Abstract
The electron-hydrogen ionization cross section has been calculated in a 1s2s2p pseudo-state approximation at impact energies of 20.4, 27.2, 54.4 and 81.6 eV. Excellent agreement is attained with the experimental curve of Fit and Brackmann (1958) at impact energies up to 27.2 eV while above 27.2 eV the pseudo-state curve falls monotonically with increasing impact energy from their experimental curve. Comparison is also made up to 23 eV impact energy with the more recent experimental result of McGowan and Clarke (1968) where detailed agreement is not so good.