Electron Transfer in Dilute Gold Alloys

Isomeric chemical shifts were observed in the Mössbauer spectra of Au197 atoms in dilute solutions in 19 metals and semiconductors at 4.2°K. The shifts were interpreted as arising from transfer of (conduction) electrons in the 6s shell of gold, probably toward the gold atom, in the alloys. A correlation was found between the shifts and the host electronegativities. The relationship between the 6s electron of gold and the nickel d bands in gold—nickel alloys is discussed. It is shown that the ground and first excited nuclear states of Au197 have radial charge moments sufficiently different (the excited state is probably ``larger'') to require collective nuclear excitation. The isomeric shift in Al2Au does not directly confirm the electroneutrality hypothesis for intermetallic compounds.