Soft-X-Ray Appearance Potential Spectra of Ni/Cu Alloys

Appearance potential spectra from Ni/Cu alloys reveal that in no case do $d$ holes enter the sites of Cu atoms, but on the other hand that $d$ holes at Ni sites exist even at Cu contents of more than 55%. The derived densities of states at the Fermi level are in very good agreement with results of Stocks, Williams, and Faulkner, calculated on the basis of the coherent potential approximation.