Calculations of He(2 1,3S)+H ionization cross sections using a b i n i t i o potentials and widths derived from Siegert eigenvalues

Associative and Penning ionization cross sections are calculated for collisions of H atoms with He(21S) and He(23S) in the energy range 0.01–1.0 eV, using the classical theory of Miller. Ab initio potential energy curves V* and widths Γ recently obtained by the author from the variational calculation of the Siegert eigenvalues for these systems are used. Generally good agreement with the previous theoretical work of Hickman and Morgner is obtained. In addition, somewhat better agreement of the present results with the available experimental data, especially for the singlet total ionization cross section, demonstrates that the Siegert potentials and widths are reasonably accurate.