Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)

O 42.62: Poster

Mittwoch, 25. März 2009, 17:45–20:30, P2

Co-porphyrin molecules on metal surfaces: from single molecules to molecular arrays and bilayer islands — •Willi Auwärter, Knud Seufert, Florian Klappenberger, Joachim Reichert, and Johannes V. Barth — Physik Department, TU München, Germany

We report on scanning tunneling microscopy (STM) and spectroscopy (STS) experiments on Co-tetraphenylporphyrin (CoTPP) molecules adsorbed on Ag(111) and Cu(111) surfaces. Starting by a characterization of the electronic and geometric structure of individual CoTPP's, we proceed to CoTPP arranged in highly organized arrays, where we discuss subtle modifications of the electronic structure induced by the packing of CoTPP. The inequivalent adsorption sites of CoTPP assembled in islands on Ag(111) results in a moire-type modulation of the lowest unoccupied molecular orbital. In a next step we address the imaging of CoTPP molecules immobilized on a CoTPP monolayer. The modification of the electronic structure clearly indicates that these 2nd layer molecules are electronically decoupled from the metal substrate. In addition, we compare the morphology of CoTPP on Cu(111) and Ag(111) with free-base porphyrins, which allows us to discuss the influence of specific molecule-substrate interactions on the molecular conformation and the mobility.