SOFT-X-RAY EMISSION AND THE LOCAL DENSITIES OF STATES IN CU-NI ALLOYS

Calculations of the L alpha soft X-ray emission spectra of Cu-Ni alloys using the muffin-tin form of the coherent potential approximation (KKR-CPA) are presented. The transition matrix elements are determined exactly within the KKR-CPA, and lifetime broadening is included. The results of new experiments on the L alpha spectra are also reported and combined with X-ray photoemission measurements of the core state binding energies, so that the relative positions of the Cu and Ni emission bands may be determined. Good agreement between theory and experiment is found, confirming the KKR-CPA description of the local densities of states in Cu-Ni alloys. Striking non rigid-band behaviour is observed. It is suggested that soft X-ray studies of the type the authors describe should be a useful probe of alloy potential functions.