Electronic structure of TiO2 monolayers grown on Al2O3 and MgO studied by resonant photoemission spectroscopy

The electronic structure of the TiO2–Al2O3 and TiO2–MgO interfaces have been studied using resonant photoemission spectroscopy. To this end, respective TiO2 monolayers have been grown on both substrates. Valence band photoemission spectra through the Ti 2p→3d absorption edge, i.e. 455–470 eV, have been measured. The results have been analysed in terms of the constant initial state curves. On-resonance minus off-resonance difference spectra have been used to separate the contribution to the valence band of the Ti 3d states for both monolayers. From the comparison of the results obtained for each interface it is inferred that the covalent–ionic character of the substrate affects the Ti–O bonding at the interface and the Ti 3d statesʹ contribution to the valence band.