Elektronenspektroskopische Untersuchungen an Vanadiumoxidoberflaechen

The (001) surface of a vacuum-cleaved V_2O_5 single crystal has been studied using UV-photoelectron spectroscopy (ARUPS), thermal desorption spectroscopy (TDS), and high-resolution electron energy loss spectroscopy (HREELS). Special emphasis was put onto the interaction with hydrogen, the existence of hydroxyl groups on the surface, and the adsorption of small molecules. Only at very high doses of molecular hydrogen, significant modifications of the spectra occur. Dosage of atomic hydrogen induces a reduction of the V_2O_5(001) surface as is obvious from the evolution of intensity near to the Fermi edge in the photoelectron spectra. Even after strong reduction of the surface, no indications of OH groups on the surface could be observed in the spectra. A detailed inspection of the ARUPS and HREELS data and comparison with theory leads to the conclusion that the defects on the surface are most likely missing bridging oxygen atoms whereas the terminal oxygen atoms of the vanadyl groups appear to be stable with respect to removal by atomic hydrogen.SIGLEAvailable from: http://www.diss.fu-berlin.de/2001/128/index.html / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman