Synchrotron-radiation-excited soft-x-ray-fluorescence studies of Cu and Zn: On the validity of the sudden approximation

Abstract

The ${\mathit{L}}_{23}$ x-ray-emission spectra of Cu and Zn have been recorded using tunable-synchrotron-radiation-excited fluorescence spectroscopy. The satellite structure was studied in detail by varying the excitation energy from threshold to several hundred eV above. Strong satellites are observed which can unambiguously be associated with the decay of multiply excited states. This disproves recent claims of a breakdown of the sudden approximation in this regime.