Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 59: Poster Session II (Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: arrays; Nanostructures at surfaces: Wires, tubes; Nanostructures at surfaces: Other; Plasmonics and nanooptics; Metal substrates: Epitaxy and growth; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsoprtion of organic / bio molecules; Metal substrates: Adsoprtion of inorganic molecules; Metal substrates: Adsoprtion of O and/or H; Metal substrates: Clean surfaces; Density functional theory and beyond for real materials)

O 59.21: Poster

Mittwoch, 24. März 2010, 17:45–20:30, Poster B1

Pentacene on insulators and the growth of nanocrystals: an STM study with submolecular resolution — •Alexander Kabakchiev¹, Klaus Kuhnke¹, Theresa Lutz¹, and Klaus Kern^1,2 — ¹Max Planck Institut für Festkörperforschung, Stuttgart, Germany — ²Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland

Pentacene has become the drosophila of single molecule imaging. Molecular orbital maps in conjunction with tunneling spectroscopy provide new insight in the local electronic structures of model adsorbates. We use the dewetting of Pentacene films on thin insulating layers to grow nanocrystals a few nm high and base dimensions of several 100 square nanometers. Scanning tunneling microscopic (STM) topography reveals steep crystal edges reaching down to the bare insulator. Submolecular spatial resolution allows to image molecular orbitals on top of the crystal and to determine the local molecular structure. We demonstrate that in contrast to thin film structures so far found on insulators, the crystallites forming on KCl layers below room temperature exhibit a bulk-like phase with the long molecular axis oriented parallel to the surface. Comparison of scanning tunneling spectroscopy for the crystal phase with isolated molecules on the insulator layer indicates a shift of the molecular orbitals to lower binding energies.