The adsorption and ordering of molecules at well-defined TiO2 surfaces are investigated by a combination of scanning tunneling microscopy and density functional theory calculations. The interplay between molecule-substrate and intermolecular interaction can give rise to ordered overlayer structures of the molecules. The influence of surface structure on the adsorption of molecules is explored on the example of carboxylic acid adsorption on the rutile TiO2(110) versus TiO2(011)-2x1. On the (110) surface a well-ordered molecular superstructure is formed due to a bridge-bidentate adsorption of a carboxylate. In contrast the surface reconstruction of the (011) surface strongly modifies the adsorption. A partial lifting of the surface reconstruction as a result of the strong molecule-substrate interaction results in an anisotropic adsorption forming quasi-one dimensional carboxylate clusters. In a second part of this talk we investigate the adsorption of a nitro-group containing molecule (2-4 dinitrotoluene). Unlike carboxylic acid that adsorbs through the dissociation of the acidic proton, we show that nitro-group containing molecules may adsorb molecularly intact. On the rutile (110) surface an ordered monolayer structure may be observed for 2-4 dinitrotoluene for saturation coverage at room temperature.

Ordered molecular monolayers on single crystal TiO<sub>2</sub> surfaces

247th National Meeting (2014)

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Ordered molecular monolayers on single crystal TiO2 surfaces

Ordered molecular monolayers on single crystal TiO₂ surfaces