Cu L-Spectra of YBCO, Bi-2212, and Related Cuprates

Cu L x-ray spectra were determined using wavelength dispersive spectrometry on an electron microprobe for cuprates including YBCO and Bi-2212. Pure emission spectra of the Cu are constant but the measured emission spectra differ because of differences in the Cu absorption spectrum. YBCO that is non-superconductive or under-doped has a different spectrum from optimally doped. A Sr peak appears in the Cu L spectrum of Bi-2212 so the technique could not be used for that material. A consideration of many cuprates shows that there are systematic changes in spectra not related to Cu valence but to shifts in the Cu L edges with atomic environment.