Shape resonances in photoionization of diatomic molecules: An example in thed inner shell ionization of the hydrogen halides

Abstract

A classification of the shape resonances in the photoionization of diatomic molecules into two types is proposed: the well known molecular shape resonances which appear in the σu channel for the photoionization of the σg shells of light molecules like 3σg in N2 or in O2, and the atomic-like shape resonances. To illustrate this last class of shape resonances, calculations in the frozen core static exchange approximation of thed inner shell photoionization cross sections, σ, and of the angular distribution parameters, β, are performed for both HBr and HI. In our model, the σ and β curves look roughly like that of the isoelectronic Kr and Xe rare gases, but in order to obtain quantitative agreement with experiment, an approach including interchannel interactions, i.e. similar to that used for the halogen atoms would be probably necessary.