Multi-step post-collision interaction effects in K-shell photoionization of Kr

Yield spectra of multiply charged ions produced from cascade decays followi ng K-shell photoionization of Kr have been measured in coincidence with thr eshold photoelectrons having near-zero kinetic energies (<0.05 eV). These o bserved yield spectra exhibit characteristic profiles of multi-step post-co llision interaction effects induced by the cascades. Peak shifts of the pro files do not increase gradually along with the increase of the charged stat es, but bring about a step-like structure as a function of charge state. Th e step-like structure is due to the participation of radiative decays in th e cascades following the K-shell photoionization.