Partial densities of states in amorphousPd0.81Si0.19

Photoemission and Auger spectra involving both core and valence electrons have been measured for Pd, Si, and $a$-${\mathrm{Pd}}_{0.81}$ ${\mathrm{Si}}_{0.19}$. Partial Pd $4d$, Si $3p$, and Si $3s$ densities of states (PDOS) have been derived from these measurements. The Pd $4d$ PDOS shows a filling of the $4d$ shell in the amorphous alloy which is accompanied by characteristic changes in the spectral shape of the $4d$ bands when compared to Pd. The Si PDOS can be divided into $3p$ derived states that overlap the Pd $4d$ PDOS and a corelike $3s$ portion that is located ∼ 7 eV below the center of the Pd $4d$ PDOS. The Si $3p$ PDOS is bifurcated as a result of Pd $4d$-Si $3p$ hybridization with a local maximum at $E_F$. The Si PDOS is well described by an extension of the virtual-bound-state model of Friedel and Anderson owing to Terakura. Core-level shifts of the order of 0.35 eV reflect changes in relaxation rather than a charge transfer from Si to Pd.