CHARGE REDISTRIBUTION IN AU-METALLOID INTERMETALLICS - A AU L(2,3)-EDGE X-RAY-ABSORPTION STUDY

Au L2,3-edge x-ray-absorption near-edge-structure experiments have been performed to study the d-hole distribution at the Au site in a series of Au-metalloid compounds, AuM2 (M=Al, Ga, In, Sn, Sb, and Te). It is found that there is a noticeable white line at the Au L2,3 edge in all of the AuM2 compounds and there exists a strong correlation between the increase in the white-line intensity at both the L2 and L3 edges and the difference in electronegativity between Au and the host metalloid. These results are attributed to 5d charge depletion (increase in 5d-hole count) at the Au site upon alloying. Using the difference in area under the white line between alloy and pure Au, we have estimated changes in the d3/2- and d5/2-hole count at the Au site relative to that of pure Au. The d-hole count at the alloy Au site increases as the host metalloid becomes more electropositive. This result independently confirms the validity of 5d charge depletion at the Au site upon alloying as previously prescribed by the charge-compensation model based on x-ray photoemission and Mössbauer measurements. The effect of the Au 5d charge depletion on the Au 5d band in AuM2 is also discussed. © 1995 The American Physical Society.