The valence-band electronic structure of clean and Pt-covered TiO2(110) surfaces studied with photoemission spectroscopy

Abstract

The valence-band electronic structure of the (1×1) non-reconstructed and Pt-covered TiO 2 (110) surface is reported, employing photon energy-dependent and angular-resolved photoelectron spectroscopy with synchrotron radiation. The energy dispersion, E ( k ), is mapped as a function of the crystal momentum, k , along the Γ – Σ – M high-symmetry direction in the bulk Brillouin zone as well as along the high-symmetry directions Γ – Σ – M and Γ – Λ – Z in the surface Brillouin zone. For the clean surfaces four valence states exhibiting a weak dispersion are found and, subsequently, the effect of platinum overlayers on the electronic structure is shown for coverages, Θ Pt , below one monolayer. The occupied Pt states above the TiO 2 valence-band maximum show a splitting into two Pt states. For Θ Pt =0.2 monolayers these states do not show a Fermi edge. For Θ Pt ≥0.5 monolayers, they are filled up to the Fermi energy. The absence of a Fermi surface, however, indicates that a long-range ordering of Pt atoms in the clusters does not exist. © 1997 Elsevier Science B.V.