Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 8: Metal Substrates: Adsorption of Organic/Bio Molecules I
O 8.9: Vortrag
Montag, 25. Februar 2008, 14:00–14:15, MA 041
Low dimensional electronic structure of a metal/organic interface — •Isabel Fernández Torrente1, Nora González Lakunza2, Katharina Jennifer Franke1, Nicolás Lorente3, Andrés Arnau2, and José Ignacio Pascual1 — 1Institut für Experimentalphysik, Freie Universität Berlin, Germany — 2Unidad de Física de Materiales, Centro Mixto CSIC-UPV/EHU, San Sebastián, Spain — 3Institut de Ciencias de Materials de Barcelona-CSIC, Barcelona, Spain
The TTF-TCNQ charge donor-acceptor complex is a prototypical organic metal. In bulk, it crystallizes in a monoclinic structure built up from parallel stacks of TTF and TCNQ, showing anisotropic conduction along the molecular rows. Our aim is to study the interface of a TTF-TCNQ organic film with a metal. By means of Low Temperature Scanning Tunneling Microscopy and Spectroscopy (LT-STM and STS) we characterise the structure and electronic properties of sub-monolayer films of TTF-TCNQ grown on Au(111). Both molecular species adsorb with a planar configuration. Nevertheless there is a strong donor-acceptor recognition and TTF and TCNQ self-assemble in alternating one-dimensional rows. This arrangement modifies strongly the electronic properties of the molecular entities and the surface state inducing the formation of a resonance with one-dimensional nature delocalised along the TCNQ rows. Ab-initio calculations explain the origin of the detected resonances by a strong modification of the surface state of the underlying metal upon hybridisation with TTF on the mixed TTF-TCNQ phase.