Results are reported on photoemission and resonant photoemission (ResPES) measurements performed on a Ba-deposited TiO2 (110) using synchrotron radiation. For coverages less than 1 monolayer (ML) of Ba, only oxidized and no metallic Ba states were detected, and in the valence band spectra a new gap state, attributed to Ti3+, was seen at 0.8 eV below the Fermi edge and shown by ResPES to give a characteristic 3p→3d resonance of Ti. When the Ba thickness exceeds 1 ML, a resonance of the near-Fermi-edge bandgap state appears, with a maximum found for the Ba 4d→4f resonant transition. The metallic nature of the layers thicker than 1 ML is confirmed by an asymmetry of the Ba 4d peak. Work function measurements showed an abrupt change with Ba thickness when approaching 1 ML, in consistence with the above results.
A photoemission and resonant photoemission study of Ba deposition at the TiO2 (110) surface
SAMBI, MAURO;GRANOZZI, GAETANO
1999
Abstract
Results are reported on photoemission and resonant photoemission (ResPES) measurements performed on a Ba-deposited TiO2 (110) using synchrotron radiation. For coverages less than 1 monolayer (ML) of Ba, only oxidized and no metallic Ba states were detected, and in the valence band spectra a new gap state, attributed to Ti3+, was seen at 0.8 eV below the Fermi edge and shown by ResPES to give a characteristic 3p→3d resonance of Ti. When the Ba thickness exceeds 1 ML, a resonance of the near-Fermi-edge bandgap state appears, with a maximum found for the Ba 4d→4f resonant transition. The metallic nature of the layers thicker than 1 ML is confirmed by an asymmetry of the Ba 4d peak. Work function measurements showed an abrupt change with Ba thickness when approaching 1 ML, in consistence with the above results.
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