Comparative study of fluorescence- and electron-yield detection on ${\mathrm{YB}}_2$${\mathrm{Cu}}_3$${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ at the O K edge through x-ray absorption

The near-edge and extended x-ray absorption fine structures of ${\mathrm{YBa}}_2$ ${\mathrm{Cu}}_3$ ${\mathrm{O}}_{7\mathrm{-}\mathrm{\delta }}$ have been studied above the O K edge in ultrahigh vacuum by means of electron and O Kα fluorescence yields (probing depths of ∼100 and 2000 Å). The electron yield data significantly differ from the fluorescence-yield ones. Upon scraping the sample’s surface only the fluorescence yield data remain unaffected establishing this technique as the appropriate one for photoabsorption at the O K edge.