Photoelectron spectroscopic study of the valence and core-level electronic structure ofBaTiO3

We present valence and core-level photoemission measurements from vacuum-fractured, single-crystal barium titanate. These results resolve contradictory measurements in the literature which have employed other methods of sample surface preparation. The valence-shell electronic structure is compared with previously published results of band structure and cluster calculations. Resonant photoemission is used to probe the covalent coupling between titanium and oxygen in the cubic and tetragonal phases of this ionic compound. Photoelectron spectra of the Ti 2p and O 1s core levels reveal the valence of these two ions to be ${\mathrm{TiO}}_2$-like. Valence, core, satellite, and Auger transitions are also assigned and tabulated.