  Silicon thin films for coverages ($\theta$) between 0.3 and 3 monolayers have
been grown on rutile \ce{TiO2}(110)-(1x1) at room temperature and studied by
x-ray and ultra-violet photoelectron spectroscopies, Auger electron
spectroscopy, and low energy electron diffraction (LEED). A clear evidence of a
strong \ce{Si}/\ce{TiO2} interaction consistent with the high affinity of O for
Si has been found. The Ti cations on the substrate are reduced, while the Si
film is oxidized, yielding \ce{SiO2} and a mixture of silicon suboxides.
Neutral Si atoms are observed at a coverage of 3 monolayers. At the interface
region we observe the formation of cross-linking Ti-O-Si bonds. The thin Si
overlayer strongly attenuates the $(1 \times 1)$ LEED pattern from the
substrate. Finally, thermal annealing results in the improvement of the
\ce{SiO2} stoichiometry, but the surface order is not recovered. Using
ab-initio density functional theory we have obtained optimum geometrical
configurations and corresponding density of states for 1/3 \le \theta \le 1$
monolayers of Si adsorbed on the $1 \times 1$ two-dimensional unit cell.
