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Abstract:
Valence band photoemission spectra have been measured from in situ thermally grown ZrO2 using synchrotron radiation. Resonant photoemission was observed at photon energies hv ≈ 39 eV, well above the Zr4p → 4d threshold. The phenomenon has been used to identify the Zr 4d derived valence states and good agreement was found with valence band structure calculations. Ar+ bombardment of ZrO2 causes the growth of an emission feature in the band gap at a binding energy of 1.5 eV associated with oxygen vacancies as well as a second band at 3.5 eV and other changes in the O 2p band, all of which are clearly associated with the formation of a highly oxygen deficient surface layer. Resonant photoemission of the bombarded oxide not only demonstrates the d-character of the states in the band gap but also shows a significant increase of the Zr contribution to the O2p band.
