Satellite lines in photoelectron spectra

A general theoretical framework is presented for treating satellite line intensities in photoelectron spectra. It is shown that aside from multiplet structure characteristic of open shell systems, satellite lines involve a breakdown of the one-electron or single particle approximation. For any choice of independent electron basis states, this breakdown can be in the form of initial state configuration interaction, final ionic state configuration interaction, or interchannel coupling (configuration interaction) among the various possible photoionization channels (ion plus photoelectron system). This last effect has not been discussed in connection with photoelectron spectroscopy but its consequences can be extremely important.