Evolution of the Cu [Formula Presented] satellites from threshold to saturation

Photoexcited Cu [Formula Presented] satellite spectra were measured as a function of excitation energy, from threshold at [Formula Presented]10.010 keV to saturation at [Formula Presented]11 keV. A two-regime behavior is found, where in the near-threshold regime (TR) both the shape and the intensity of the spectrum vary. In the higher-energy regime (GR) only the intensity varies but not the shape. The GR spectra are well described by relativistic Dirac-Fock calculations. The analytic Thomas model, applicable in this adiabatic regime, does not agree well with the measured intensity variation with excitation energy. The continuous intensity rise from zero at threshold confirms the shake theory prediction of a pure shake-off process for inner-shell, medium-[Formula Presented] atom satellites. The thresholds for the individual spectral features, the overall shape variation, and the variations of the individual lines in the TR regime are determined, and discussed.