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

► We present a short review of post collision interaction (PCI), as evidenced in coincidence experiments. ► Our experiment uses synchrotron radiation and a magnetic bottle time of flight electron spectrometer. ► Emphasis is put on PCI effects occurring when inner shell ionization is followed by emission of two Auger electrons.