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O: Fachverband Oberflächenphysik
O 22: Poster Session - 2D Materials Beyond Graphene: Growth, Structure and Substrate Interaction
O 22.4: Poster
Montag, 16. März 2020, 18:15–20:00, P1A
When halogene atoms do not guide the selfassembly of GNR precursor molecules — •Christoph Dobner1, Jacob Teeter2, Paulo Costa3, Alexander Sinitskii2, and Axel Enders1,3 — 1Physikalisches Institut, Universität Bayreuth, 95440 Bayreuth — 2Department of Chemistry, University of Nebraska - Lincoln, Lincoln NE 98588, USA — 3Department of Physics and Astronomy, University of Nebraska - Lincoln, Lincoln NE 98588, USA
The on-surface selfassembly of the prototypical precursor molecule for graphene nanoribbon synthesis, 6,11-dibromo-1,2,3,4-tetraphenyltriphenylene (C42Br2H26), and its non-brominated analog hexaphenylbenzene (C42H30), was investigated as a function of thermal treatment using scanning tunneling microscopy. The "herringbone" reconstructed surface of Au(111) was used for all growth studies, and all experiments have been carried out under ultrahigh vacuum conditions. It is found that for sufficiently high substrate temperatures, there is no halogene-guided selfassembly of the brominated molecules, in stark contrast to the well-known formation of chevron-shaped GNRs from these precursors. Instead, both species, the brominated and non brominated ones, form identical one-dimensional structures consisting of fully planarized and cyclized molecules on the surface. For hexaphenylbenzene, which form non-covalent two-dimensional networks at room temperature, a thermally induced transition of the network structure could be achieved by moderate annealing, which is likely driven by π-bond formation.