AU-197 MOSSBAUER ISOMER-SHIFT IN AU-CA AND AU-AG ALLOYS - THE ROLE OFTHE AU 5D ELECTRONS

The Au-197 Mossbauer isomer shift (IS) for a series of Au-Cu and Au-Ag alloys is correlated with the change in the 5d electron population (5 d hole count) at the Au site upon alloying. The Au 5d hole counts have been derived from the area under the whiteline of the Au L(3,2) edge X-ray absorption near edge structures (XANES) of the alloys. It is fou nd that there exists a linear corelation between IS and Au 5d hole cou nts, indicating that the redistribution of 5d electrons has a signific ant effect on the isomer shift. From the IS-5d hole correlation, the r atio of 5d loss to 6s gain (Delta n(d)/Delta n(s)) is determined to be -0.62.