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O: Fachverband Oberflächenphysik
O 18: Poster Session I - MA 141/144 (Atomic Wires; Size-Selected Clusters; Nanostructures; Metal Substrates: Clean Surfaces+Adsorption of Organic / Bio Molecules+Solid-Liquid Interfaces+Adsorption of O and/or H; Surface or Interface Magnetism; Oxides and Insulators: Clean Surfaces)
O 18.23: Poster
Montag, 25. Februar 2008, 18:30–19:30, Poster F
C68 deposits on Cu(111): Topography and Electronic Properties — •Albert F. Takacs1,2, Timofey Balashov1, Wulf Wulfhekel1,2, Daniel Löffler3, Artur Böttcher3, and Manfred M. Kappes2,3 — 1Physikalisches Institut, Universität Karlsruhe, D-76131, Germany — 2CFN-DFG Centrum für Funktionelle Nanostrukturen — 3Institut für Physikalische Chemie, Universität Karlsruhe, D-76131, Germany
Non-IPR fullerenes (Isolated Pentagon Rule) have very recently attracted attention as stable building blocks for carbon-based nanotechnology. In contrast to classic fullerenes, the smaller Cn cages, n<70 and n>60, are functionalised by terminating reactive sites. We focus here on the C68 species which is the largest fullerene to have only non-IPR cage isomers. Ultraviolet photoionization spectroscopy reveals the HOMO-LUMO gap of the C68 layers of 1.7 eV and thermal desorption spectroscopy evidences a high intercage binding energy of ≈2 eV. We also used scanning tunnelling microscopy(STM) to determine the geometry and electronic properties of C68 deposits on Cu(111). The STM images confirm that C68 deposits comprise cages linked in polymeric chains as determined by the geometry of the reaction centers terminating individual cage. By proper positioning and approaching of the STM tip over an individual molecule we have investigated the conductance across the cage-substrate interface. The resulting current-voltage (I-V) and differential conductance (dI/dV) characteristics reveal two distinct trends which indicate the unique role of the non-IPR sites as responsible for the strong interactions with the substrate.