Resonant photoemission of anataseTiO2(101) and (001) single crystals

The resonant behavior of anatase ${\mathrm{TiO}}_2$ (101) and (001) surfaces has been investigated using synchrotron photoemission spectroscopy. The data are compared with earlier photoemission work from rutile ${\mathrm{TiO}}_2\mathrm{}\left(110\right)\mathrm{}$ and calculations for bulk anatase in order to elucidate the degree of Ti-O hybridization in the valence band. The results for the (101) surface show good general agreement with bulk band-structure calculations. Deviations from the bulk band structure in the case of the (001) surface are attributed to the reconstruction of this surface. A small peak is observed at around 1 eV binding energy (relative to the Fermi energy) for both surfaces following the creation of surface defects (O vacancies), which is thought to arise from surface ${\mathrm{Ti}}^{3+}.$ The attenuation of this peak by gentle heating in ${\mathrm{O}}_2$ is attributed to healing of the surface O vacancies.