X-ray-absorption studies of Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O films at oxygen K edge by means of fluorescence and total electron yield: A comparison of two techniques

X-ray fluorescence and total electron yield around the oxygen K edge of high-Tc Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O superconductor films were measured. The oxygen fluorescence spectra in these materials were obtained by using a new parallel-plate avalanche detector and a high-resolution soft-x-ray spectrometer. Comparison of the fluorescence results with total electron yield and with other data indicates that the fluorescence method is free from spurious features caused by contaminants and oxygen-depletion layers, as usually found in the electron-spectroscopy measurements, and that meaningful information on photoexcitation of core electrons at the oxygen sites can be readily obtained by these bulk-sensitive measurements.