Regensburg 2010 – scientific programme

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O: Fachverband Oberflächenphysik

O 12: Oxides and insulators: Adsorption

O 12.9: Talk

Monday, March 22, 2010, 17:00–17:15, H33

Adsorption of cobalt phthalocyanine on rutile TiO2 (110) surfaces: interface formation. — •Pavel Shukrynau, Marius Toader, and Michael Hietschold — Chemnitz University of Technology, Institute of Physics, Solid Surfaces Analysis Group. D-09107 Chemnitz, Germany.

We have employed variable temperature scanning tunneling microscopy (STM) to follow the adsorption of cobalt phthalocyanine (CoPc) on rutile TiO2 (110)-1x1 and -1x2 substrates. The coverage of CoPc varied from 0.05 up to 1 monolayer (ML). At room temperature and very low coverage single pthtalocyanine molecules either lay flat on the surface over the bridging oxygen atomic lines or stay tilted in troughs between them. Further deposition of CoPc leads to the agglomeration of the molecules and finally results in the formation of irregularly disordered films on both substrates. At a coverage of about 0.75 ML the surfaces are completely covered with roundly shaped 3D clusters of typical size up to 3 nm. The general structure of the surface, i.e., shape of the step edges, remains unchanged. Subsequent annealing of the samples up to 300°C results in the rearrangement of the adlayer and forms the molecular rows along [001] direction of the substrate. STS spectra taken at different coverages give an information about the electronic properties of the interface, revealing the adsorption mechanism of molecules on this substrate.