title: Charge transfer from an aromatic adsorbate to a semiconductor TiO(2) surface probed on the femtosecond time scale with resonant inelastic x-ray scattering.
abstract: The excited state charge transfer dynamics of an aromatic adsorbate to a rutile TiO(2) surface is studied using a core-hole clock (CHC) implementation of resonant inelastic x-ray scattering (RIXS) on the low femtosecond time scale. Comparing the abundance of the elastic and inelastic radiative N 1s core-hole decay channels provides a method for probing ultrafast injection of electrons resonantly excited to unoccupied molecular orbitals that lie above the conduction band of the substrate on the time scale of the core-hole lifetime. The method is analogous to the CHC implementation of resonant photoemission, but in the case of RIXS it is the emitted soft x-ray photons that are measured rather than photoelectrons, leaving the probed molecules in a neutral rather than ionized final state. The results reveal a charge transfer time of 2.8±1.5  fs from the lowest unoccupied molecular orbital +1 state of adsorbed bi-isonicotinic acid to the conduction band of the TiO(2) substrate.
authors.affiliation: School of Physics and Astronomy and Nottingham Nanotechnology and Nanoscience Centre, University of Nottingham, Nottingham, NG7 2RD, United Kingdom.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Britton
authors.forename: Matthew
authors.initials: M
authors.lastname: Weston
authors.forename: James N
authors.initials: JN
authors.lastname: O'Shea