Polarization-dependent ARPES measurement for valence band of anatase TiO2

Angle-resolved photoelectron spectroscopy utilizing linearly polarized synchrotron radiation was conducted to examine the electronic structure of an anatase TiO2(001) thin film fabricated on LaAlO3(100) by pulsed laser deposition. Polarization-dependent measurements by changing the incidence angle of the light were performed to identify the orbital symmetry. Energy–momentum dispersion curves along the [001] direction are mapped and resolved into four components: O 2p-derived Pπ non-bonding, O 2p–Ti 3d σ bonding, and two π bonding states. The intensities of the π bonding states are obviously different between both polarizations while the intensities of the peaks due to Pπ and σ are almost equivalent. Two different π states with polarization dependence were attributed to Ti t1u π orbital. The result implies that the distortion of TiO6 octahedra resolves degeneracy of T1u bands and/or breaking T2g symmetry.