VALENCE-BAND PHOTOEMISSION AND AUGER-LINE-SHAPE STUDY OF AUXPD1-X

We report an experimental study of the electronic structure of the all oy system AuxPd1-x. Valence-band photoemission spectra were recorded u sing synchrotron radiation, exploiting the different photoionization c ross sections of the Au and Pd d bands to identify the spectral featur es. We find that recent electronic-structure calculations using the Ko rringa-Kohn-Rostoker method with the coherent-potential approximation (KKR-CPA) give good agreement with our results, whereas earlier calcul ations using other methods show serious discrepancies. In addition we measured the Au N6,7VV and Pd M4,5VV Auger line shapes. We find that o ne-electron calculations using the KKR-CPA results give reasonable qua litative agreement for the Au line shapes across the alloy series. Sim ilar agreement is found for the Pd Auger line shapes at high Pd concen trations, but this breaks down for low Pd concentrations. We suggest t hat this disagreement results from a neglect of many-body interactions rather than a problem with the KKR-CPA calculations.