Cu-L X-RAY EMISSION SPECTRA FROM HIGH-Tc SUPERCONDUCTORS Y-Ba-CU-O BELOW AND ABOVE THE CRITICAL TEMPERATURE

The copper Lα and Lβ x-ray emission spectra from high-Tc Y-Ba-Cu-O superconductors, above and below the critical temperature, have been measured in a laboratory x-ray spectrograph. The Zn-Lα (1011 eV) photon energy was used to produce the Cu-2p1/2,3/2 primary vacancies (binding energies ~950 and 930 eVs, respectively). Changes in Cu-L x-ray emission spectra were observed indicating small changes in population of 3d and 4s electrons in the valence band when superconducting. For comparison Cu-L emission spectra £rom metallic Cu and £rom polycrystalline Cu2O (valence I) and Cu0 (valence II) were recorded at room temperature