Theoretical study of the photoionisation of H2

Abstract

A theoretical calculation of the photoionisation of H₂ by 736 AA radiation is carried out. The calculated ratios of the cross sections for the (0-0) and (0-2) rotational transitions for individual vibrational transitions agree with the results of multichannel quantum defect theory and with experimental results. The symmetry parameter beta _s for the S rotational branch in the (0-0) vibrational transition is 0.643 when the f wave of the ejected electron is taken into account. This value is in good agreement with the value beta _s=0.62+or-0.11 deduced from the experimental data of Ruf et al. (1983). It is shown that even when the energy of the photoelectron is below 1.4 eV the interference of the p and f waves of the ejected electron gives a larger contribution to beta _s than the pure-p-wave contribution.