Calculation of vibrational preionization in H2 by multichannel quantum defect theory: Total and partial cross sections and photoelectron angular distributions

Abstract

Multichannel quantum defect theory has been used to calculate the effect of vibrational preionization on the total and partial oscillator strength distributions and photoelectron angular distribution in H₂ for excitation between 790 and 760 Å. The total oscillator‐strength distribution obtained agrees well with the high‐resolution photoionization data of Dehmer and Chupka. The partial oscillator strength resonance profiles are predicted to have different shapes in different vibrational ionization channels, while their widths change little with channel. The preionization resonances are also predicted to affect the angular distribution asymmetry parameters b over a broader range than they affect the oscillator strength distribution. The gross features of the preionization resonances are discussed in terms of approximate solutions of the MQD equations.