The selective adsorption and kinetic behaviour of molecules on observed by STM and NC - AFMTiO 2 ( 110 )

In the present paper we report a kinetic aspect of molecules on terraces and steps of a surface as observed by scanning probe microscopy, which may be TiO2(110)-(1] 1) relevant to oxide catalysis. When the surface, heated at 400È450 K, was exposed to a 2 formic acid ambient of 1È2 ] 10~6 Pa, small particles were formed on terraces. Post-reaction STM observation revealed that the particle formation was strongly suppressed in the vicinity of single-atom height steps. The suppressive e†ect of the steps ranged 2.4 nm into the terrace. Formate ions (a possible reaction intermediate) were imaged in-situ during formic acid exposure at the reaction temperature. The local density of the formates and hence the product distribution, which were very low near the steps, were simulated by a model. The particles produced were suggested to be carbonates, on the bridging oxygen atoms of the surface. CO32~ 2