S K-edge NEXAFS spectra of model systems for SO2 on TiO2 (110): a TDDFT simulation.

The time dependent density functional theory approach has been employed to simulate the S K edge absorption spectra of model systems for the adsorption of SO(2) on TiO(2) (110) regular surface, employing cluster models to mimic the rutile surface. The spectra calculated for the adsorbate models are compared with the spectrum of the free SO(2) in order to discuss the nature of the adsorbate-substrate interaction in terms of the differences in the core excitation spectra. The comparison with the experimental NEXAFS spectra, measured at different temperatures, is satisfactory at low temperature while it reveals the difficulty of reproducing the complex experimental situations induced by the temperature increase with an adsorption model based on a perfect TiO(2) surface.