The use of Cooper minima effects and resonant photoemission in the study of the electronic structure of dilute alloys

Abstract. It is shown that photon energy dependent photoemission, using a synchrotron radiation source, IS a useful tool in studying the electronic structure of alloys. In AuNi a satellite structure at 1.9 eV is identified using a combination of cross-section effects and resonant photoemission. A model calculation is used to show that our observations are consistent with the magnitude of parameters describing the electronic behaviour in terms of correlation and hybridisation. obtained from other techniques. Recently various studies of dilute alloys of 3d metals in noble metal hosts using electron spectroscopy techniques have been reported (Reehal and Andrews 1980, Andrews and Brown 1981, Bosch et a1 1982, 1984, van der Marel er a1 1984, 1985b). The reason for this interest is that these alloys represent ‘zero-bandwidth ’ 3d systems, making them suitable for the study of electron correlation in solids. It is well established that Ni impurities in Au have a 3d occupation of 9.3-9.5 electrons (Bosch er a1 1982, 1984, Julianus er a1 1981). This partial d occupation gives rise to satellite structure in the Ni2p XPS spectrum, which can be understood as reflecting 2p5d9 local final-state configurations. The many-body behaviour of Ni3d electrons leads one t