Adsorption and thermal stability of Mn on TiO sub(2)(110): 2p x-ray absorption spectroscopy and soft x-ray photoemission

X-ray absorption and photoelectron spectroscopies are used to study the adsorption and reaction of Mn films deposited on TiO sub(2)(110) at 25 degree C and after annealing to approx.650 degree C. Fractional monolayer coverages of Mn at 25 degree C produce a reactive, disordered interface consisting of reduced Ti cations and oxidized Mn overlayer atoms. Metallic Mn is found only for thicker layers at 25 degree C. Annealing Mn films to approx.650 degree C leads to several changes that are largely independent of initial overlayer coverage: Metallic Mn thermally desorbs leaving only Mn super(2+) ions; interfacial Ti cations are largely re-oxidized to the Ti super(4+) state; and the local order is increased at the interface. The formation of a crystalline ternary surface oxide, MnTiO sub(x), is proposed to account for these chemical and structural changes.