Abstract
A partitioning scheme for the photoelectron asymmetry parameter of linear molecules is proposed and applied in multiple-scattering calculations for thirteen valence ionizations of five molecules. For several limiting cases rigorous bounds for the asymmetry parameter are established. The energy dependence of photoelectron angular distributions is discussed in terms of relative channel cross sections, transition moment phases, and Coulomb phase shifts. Rapid energy-dependent variations of the asymmetry parameter can be rationalized in this manner, e.g. for low-energy Π ionizations and for σ-type resonances in Σ ionizations. The proposed scheme is also used to identify the origin of errors in approximate calculations.
