Photoelectron spectroscopy, low energy electron diffraction, and reflection high energy electron diffraction have been employed to probe the electronic and geometric structure of the TiO2(100)/K interface. Data have been obtained from two (100) oriented single crystal samples, which differ in their extent of bulk reduction. It is demonstrated that this parameter is important for both the electronic and geometric structure of ordered TiO2(100)/K surfaces, formed by annealing to similar to1000 K. Photoelectron spectra, recorded following this preparation, indicate that reduced Ti states are present for the less stoichiometric sample, which exhibits a ((1)(2) (-1)(2)) surface unit cell. In contrast, the other sample displays a c(2 x 2) overlayer, with no Ti reduction evidenced.
