Spin asymmetry in near threshold (e, 2e) process for lithium and hydrogen

The singlet and triplet cross sections and the asymmetry parameter for e-H and e-Li ionization have been calculated in a distorted-wave Born approximation for incident energies in the range 0.5 to 20 eV above the ionization threshold. The two final-state continuum electrons are assumed to share equal energy and to come out 180° apart. The variation with respect to the angle of scattering is found to be qualitatively very different in the two cases. It is found that, in the case of lithium, the ¹D and ³F components in the scattering amplitude are quite significant even at very low energies.