X-ray absorption studies of the electronic structures of Pd-Ag and Pd-Au alloys

Information on the number of unoccupied d-states in the valence band of a metal can be obtained from a study of the intensities of the X-ray absorption threshold resonances associated with LIII and LN absorption edges. Such resonances, which are attributed to excitations of electrons from 2p core levels to the unoccupied d-states, have been investigated for both Pd-Ag and Pd-Au alloys over the same range of composition. The spectra were obtained from measurements of the intensity of emission of electrons (total electron yields) from powder samples. This method avoids experimental artifacts associated with sample thickness effects of the type encountered with X-ray transmission or fluorescence measurements. The attenuating effect of the Group IB metal on the resonances of palladium in the alloys was much smaller than the effect predicted by the “rigid-band” model of the electronic structure, but substantially greater than that previously observed for Ni-Cu alloys.