Auger cascades versus direct double Auger:: relaxation processes following photoionization of the Kr 3d and Xe 4d, 3d inner shells

The relaxation processes after non-resonant inner-shell photoionization are studied experimentally using electron-electron time-of-flight coincidence spectroscopy. Results for krypton 3d and xenon 4d as well as 3d photoionization are presented. The experimental data make it possible to disentangle sequential from simultaneous processes using the different electron emission characteristics as the differentiating property. For the population of final states having charges higher than 2, the measurements show a strong preference for sequential Auger cascade decay. Clear evidence for direct double Auger processes is found in the case of Xe 3d photoionization only.