Dresden 2017 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 55: Graphene
O 55.11: Poster
Dienstag, 21. März 2017, 18:30–20:30, P2-EG
Dimerization of activated Coronene on HOPG — •Jürgen Weippert1, Julian Bachmann1, Jean-Francois Greisch1,2, Artur Böttcher1, and Manfred M. Kappes1,2 — 1Institute of Physical Chemistry, Karlsruhe Institute of Technology (KIT), Fritz-Haber-Weg 2, 76131 Karlsruhe, Germany — 2Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
We have studied the dimerization of Coronene (Cor) as a model reaction for the fabrication of tailored graphene nanoribbons (GNR). Low energy ion beam deposition of both intact monomers as well as dehydrogenated congeners was used to grow the corresponding films. The composition of the incident cationic beam can be tuned by changing the electron impact energy and by varying the selected mass range. Thermal desorption measurements indicate that this leads to the on-surface formation of Cor dimers presumably already during the film growth. We find two different reaction channels: (a) 2(Cor-2H)*(Cor-2H)2 and (b) (Cor-2H)+Cor*(Cor-H)2. While the monomers sublime at 460K the dimers (Cor-2H)2 sublime around 800K. The thermal desorption spectra indicate that the binding energy and the pre-exponential factor (EB=2.9 eV, v=1017 s-1) of on-surface-formed dimers (Cor-2H)2 are comparable to that of directly deposited Dicoronylene. We have also explored the structures of the corresponding (Cor-2H)2 and (Cor-H)2 species using a combination of laser ablation and ion mobility measurements.