From x-ray-absorption near-edge-structure (XANES) measurements, we have obtained direct evidence for 5d charge depletion at the Au site for both concentrated and dilute Au-Ag alloys. This observation, together with x-ray photoemission of Au 4f and Ag 3d core levels, shows that Au gains non-d conduction charge and loses d charge while Ag gains d charge and loses non-d conduction charge; the net charge flow is negligibly small in accordance with the principle of electroneutrality. The sensitivity of XANES in probing small changes in the Au 5d charge redistribution (∼0.02d count) and relativistic effects in alloying is noted.

• Received 12 August 1991

DOI:https://doi.org/10.1103/PhysRevB.45.8924