Hybridization and Bond-Orbital Components in Site-Specific X-Ray Photoelectron Spectra of Rutile $\mathbf{T}\mathbf{i}{\mathbf{O}}_{\mathbf{2}}$

We have determined the Ti and O components of the rutile ${\mathrm{\text{TiO}}}_2$ valence band using the method of site-specific x-ray photoelectron spectroscopy. Comparisons with calculations based on pseudopotentials within the local density approximation reveal the hybridization of the Ti $3d$, $4s$, and $4p$ states, and the O $2s$ and $2p$ states on each site. These chemical effects are observed due to the large differences between the angular-momentum dependent matrix elements of the photoelectron process.

Figure 1

Theoretical total electronic density of states (upper curve), the valence-photoelectron spectrum recorded off of the Bragg condition (middle curve), and the theoretical total electronic density of states corrected for individual Ti and O angular-momentum dependent photoelectron cross sections (lower curve). The curves have been scaled to equal peak height.

Figure 2

Photoelectron spectra from the rutile ${\mathrm{\text{TiO}}}_2(110)$ surface recorded within the photon-energy width of the ${\mathrm{\text{TiO}}}_2(200)$ Bragg back-reflection condition. The photon energies were chosen to maximize the electric-field intensity on either the Ti (solid curve) or O (dotted curve) atomic plane.

Figure 3

Theoretical partial density of states and the experimental site-specific valence-photoelectron spectrum: (a) Ti; (b) O. Theoretical and experimental curves have been scaled to equal peak height. The O component has been scaled by a factor of 4 relative to the Ti component.

Figure 4

The different angular-momentum components of the theoretical Ti and O partial density of states. Multipliers relative to the O $2p$ component are indicated in each case.

Figure 5

Theoretical partial density of states corrected for individual angular-momentum dependent photoelectron cross sections and the site-specific experimental valence-photoelectron spectrum: (a) Ti; (b) O. The curves have been scaled to equal peak height.