Structure and photo-induced charge transfer of pyridine molecules adsorbed on TiO₂(110): A NEXAFS and core-hole-clock study

The structure and photo-induced charge transfer time of pyridine molecules adsorbed on a rutile TiO₂(110) surface have been studied by near-edge x-ray absorption fine structure (NEXAFS) spectroscopy, density functional theory (DFT) calculations and core-hole-clock (CHC) spectroscopy. Polarization dependence of NEXAFS spectra and geometrical optimization by the DFTcalculations revealed that the pyridine molecules are bound to the TiO₂ surface with an upright configuration where the N atom binds to a surface Ti atom. The CHC results indicate that the charge transfer from the LUMO+2 orbital of pyridine with a Π* symmetry to the conduction band of TiO₂ is quite fast, where the timescale is less than 3 fs.