THRESHOLD BEHAVIOR OF L(3)-M(4,5)M(4,5) AUGER TRANSITIONS IN 4D METALS

The energy distribution of Auger electrons is strongly modified if the exciting photon energy is varied in the threshold region of the respe ctive inner-shell hole. Resonant inelastic scattering theory predicts this peculiar behaviour which is characteristic of the one-step transi tion from the initial ground to the final scattering state. This is ex perimentally studied for the L(3) - M(4,5)M(4,5) Auger transition in s olid Ru, Rh, Pd, and Ag. For the open d-shell metals strong, dispersin g resonance lines are observed around threshold. In the case of Ag, ho wever, sub-threshold excited spectra reveal a continuous electron dist ribution, highly asymmetric and modulated by the density of unoccupied states. Above threshold it gradually evolves into the characteristic Auger line.