PCI influence on angular distribution of Auger and autoionization electrons

The angular distribution of emitted electrons following an atomic inner-shell photoionization or an excitation of autoionizing atomic states by electron or ion impact is considered. The decay of a quasistationary state results in the creation of three charged particles in the final state of such processes. The effect of the Coulomb interaction of these particles (post-collision interaction (PCI)) on the angular distribution of Auger or autoionization electrons is studied. The general analytical formulae for the PCI distortion factor are obtained which allows us to calculate the PCI distortion influence on the angular distribution of emitted electrons. The distortion factor is calculated for the Xe N 5 -O 23 O 23 Auger electrons measured both in the coincidence and the non-coincidence experiments. The essential role of the PCI distortion is revealed for small relative angles of ejection.