CHARGE REDISTRIBUTION IN AU-AG ALLOYS FROM A LOCAL PERSPECTIVE

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 (approximately 0.02d count) and relativistic effects in alloying is noted.