THERMAL-STABILITY OF PT FILMS ON TIO2(110) - EVIDENCE FOR ENCAPSULATION

We have studied the thermal stability of ultrathin platinum films on a rutile TiO2(110) surface, using low energy ion scattering (LEIS) and X-ray photoelectron spectroscopy (XPS). At room temperature, Pt grows in three-dimensional islands on the TiO2 surface, with little indicati on of an interface reaction. Upon annealing to temperatures above 450 K in UHV, encapsulation of the Pt islands by Ti suboxides is observed; the rate of this process increases with annealing temperature and dec reases with island thickness. The Ti layer on top of the Pt islands is identified as a reduced Ti-n+ species (1 less than or equal to n less than or equal to 3) with the degree of reduction depending on the thi ckness of the Pt islands. These results are discussed in the framework of the strong metal-support interaction (SMSI) effect.