Post collision interaction probed by multi-electron coincidences: Application to the Ar 2s inner-shell photoionization

Post-collisional interaction following inner-shell ionization of atomic systems has been investigated by multi-coincidence electron spectroscopy, with a special emphasis on the decay by emission of two Auger electrons. The case of the Ar 2p hole is first reviewed. After Ar 2s inner-shell photoionization, the dominant decay channel is cascade Coster-Kronig/Auger decay. The distortion of the photoelectron peak shows a sensitivity to both the energy of the Coster-Kronig electron and to the lifetime of the intermediate Ar ²⁺ (2p ^-13l ^-1) state that is well reproduced by a theoretical model based on the eikonal approach. The dynamics of cascade double Auger decay can be clearly understood thanks to this study.