Valence Band of Rutile TiO₂(110) Investigated by Polarized-Light-Based Angle-Resolved Photoelectron Spectroscopy

Band structure dictates optical and electronic properties of solids and eventually the efficiency of the semiconductor based solar conversion. Compared to numerous theoretical calculations, the experimentally measured band structure of rutile TiO₂, a prototypical photocatalytic material, is rare. In this work, the valence band structure of rutile TiO₂(110) is measured by angle-resolved photoelectron spectroscopy using polarized extreme ultraviolet light. The effective mass of the hole, which has never been measured before, is determined to be 4.66-6.87 m₀ (free electron mass) and anisotropic. The dependence of photoemission intensities on excitation light polarization is analyzed by taking into account of the parity symmetry of molecular orbitals in the blocking unit of rutile TiO₂. This work reports a direct measurement of valence band structure and hole effective mass of rutile TiO₂(110), which will deepen our understanding of the electronic structure and charge carrier properties of the model material and provide reference data for future theoretical calculations.