Photon-stimulated desorption and total-electron yield from DyBa2Cu3O7-x between 15-180 eV.

Abstract

Results of photon-stimulated desorption (PSD) and total-electron yield (TEY) measurements on the high-${T}_{c}$ superconductor ${\mathrm{DyBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathrm{x}}$ are presented. Molecular oxygen is the major desorbing species. ${\mathrm{O}}_{2}$ PSD spectra in the energy range 60--140 eV show structure that can be interpreted in terms of excitation of Cu 3p and Ba 4d core levels. The mechanisms by which excitation of these core levels could result in desorption is discussed. In the photon energy range 10--30 eV the ${\mathrm{O}}_{2}$ PSD spectrum shows a threshold at 15 eV and a peak at 23 eV. This structure is believed to result from excitation of Ba 5p and O 2s shallow core levels with possible contributions from creation of surface and bulk plasmons. The only detectable desorbing ion was found to be ${\mathrm{H}}^{+}$. The ${\mathrm{H}}^{+}$ excitation spectra shows structure whose origin is interpreted in terms of excitation of Cu 3p and Ba 4d core levels; no structure is observed corresponding to excitation of Dy 4d electrons. The TEY spectrum shows structure which results from excitation of Cu 3p, Ba 4d, and Dy 4d electrons.