Time-and-energy resolved measurement of the cascaded Auger decay in krypton

The cascaded Auger decay following ionization or excitation with 94 eV soft-X-ray pulses from the 3d subshell in krypton has been energy-and-time-resolved for the first time. The decay time of the 4s −14p −2 nl → 4p −3 + e and/or 4s −14p −1 nl → 4p −2 + e transition is measured to be 74 ± 20 fs. Furthermore, our data shows that the electrons with a kinetic energy around 25 eV (generally assigned as 3d −1 np → 4s −2 n′p + e) emitted after core excitation are emitted in a second decay step suggesting an alternative assignment of the form 4s −2 np 4p −2 + e.