AgL-edge x-ray-absorption near-edge-structure study of charge redistribution at the Ag site in Au-Ag alloys

Ag L-edge x-ray-absorption near-edge-structure spectra have been obtained for a series of Au-Ag alloys: Au0.75{Ag}0.25$, ${Au}0.67Ag0.33, Au0.5{Ag}0.5$, and ${Au}0.25Ag0.75. The results show a significant decrease in the Ag L2,3-edge white-line area relative to pure Ag upon dilution of Ag in Au, indicating an increase in d charge at the Ag site. The value of the transition matrix element Rd2P=1.2(1)×{}10^-10 cm for Ag has been derived based on the experimental results. A semiquantitative analysis of the results shows that the number of unoccupied d states (4d hole counts) at the Ag site in the alloys decreases by as much as 0.130 in Au0.75{Ag}0.25$. The relevance of this finding to Friedel charge screening and Au-Ag d-d interaction is discussed.