Relative intensities in X-ray photoelectron spectra.: Part X. Near-threshold structure of photoionization cross-sections of molecular valence shells

Abstract

A method is described for the calculation of photoionization cross-sections of molecular orbitals using atomic cross-sections. The method is an extension of the additive scheme, and allows description of the resonance structure of the cross-sections, taking into account multiple scattering of photoelectrons by the molecular potential. Calculated photoionization cross-sections for the valence levels of N 2, CO and SF 6 are presented for excitation energies ranging from the ionization threshold to 50 eV. The results are compared with the near-threshold structure in the corresponding X-ray absorption spectra.