Microscopic View of Tin Phthalocyanine Adsorption on the Rutile TiO2(011) Surface

The adsorption behavior of tin phthalocyanine (SnPc) on the (011) face of rutile TiO2 was studied via scanning probe microscopy at room temperature. Upon deposition, the molecules form a commensurate structure (A-type phase) that exhibits two mirror domains with respect to the [01 (1) over bar] direction of the substrate. Annealing of the sample leads to the transition to another incommensurate structure (B-type phase) that mimics the structure of the corresponding molecular crystal. Kelvin probe force microscopy results showed that SnPcs tend to adsorb with the metal atom directed toward the surface unless they are in the B-type phase, where the SnPcs adopt a position in which their molecular board is perpendicular to the surface.