Photoelectron Angular Distributions as a Probe of Anisotropic Electron-Ion Interactions

Expressions are given for atomic photoelectron angular distributions in $\mathrm{LS}$ coupling in which the role of anisotropic final state electron-ion interactions emerges explicitly. Calculations of photoelectron angular distributions for atomic sulfur are presented in which these anisotropic interactions produce clear deviations from the predictions of the Cooper-Zare model. Such effects are expected to be a general feature of photoelectron angular distributions for most open-shell atoms.