Berlin 2008 – scientific programme

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O: Fachverband Oberflächenphysik

O 51: Metal Substrates: Adsorption of Organic/Bio Molecules III

O 51.8: Talk

Wednesday, February 27, 2008, 17:00–17:15, MA 041

STM and STS on Ultrathin Organic Layers of Fluorinated Cobalt Phthalocyanine (F16CoPc) on Crystalline Substrates — •Mahmoud Abdel-Hafiez, Marius Toader, Thiruvancheril Gopakumar, and Michael Hietschold — Institute of Physics, Solid Surfaces Analysis Group, Chemnitz University of Technology, D-09107, Chemnitz, Germany

Scanning Tunneling Microscope (STM) and Spectroscopy (STS) are used to study the adsorption geometry and electronic structure of isolated hexafluro-cobalt phthalocyanine (F16CoPc) molecules adsorbed on the basal plan of HOPG and Ag(110). Monolayers were prepared using organic molecular beam epitaxy (OMBE) under ultra high vacuum (UHV) conditions at room temperature and investigated at 45 K using Omicron VT-STM. F16CoPc forms a perfect quadratic superstructure independent of the substrate. In both cases a planar adsorption of molecules is observed with a non-commensurate superstructure with the substrate lattice. Moreover tunneling voltage polarity dependent contrast reversal at the cobalt center is observed, especially in the case of molecules on Ag(110). Adsorption geometry of molecules within the adlayer shows the influence of fluorine atoms in the packing. Tunneling spectroscopy and single molecule calculations are employed to understand the type of interactions between F16CoPc and the substrate, as well as the effects of fluorine atoms on the geometric configurations of the adsorbed F16CoPc molecules.