Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 61: Graphene II: Adsorption, Intercalation and Doping
O 61.9: Talk
Wednesday, March 9, 2016, 17:00–17:15, S053
Surface mediated oxidation of supported coronene molecules — •Weippert Jürgen1, Gewiese Vincent1, Böttcher Artur1, and Kappes Manfred M.1,2 — 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 explored surface-mediated oxidation of coronene (C24H12) molecules as a route to prepare molecular equivalents of graphene oxides (GOs). We found that exposure of C24H12/HOPG to a flux of atomic oxygen leads to oxidation of both the substrate and the coronene molecules adsorbed thereon (O/HOPG and C24H12On). We did not observe molecular fragments indicative of epoxy-species induced unzipping and scission of the adsorbed coronene. Instead desorption mass spectra were dominated by Coronene molecules deriving from electron impact ionization of the intact parent species, two oxidic species and an unusual coronene fragment, C21H9+. These observations suggest that sample heating activates the surface diffusion of preformed epoxy species and that subsequently pronounced fragmentation of the oxidized molecular periphery is induced either by further on-surface heating or by ionization. The reaction path results in the emission of coronene oxides with a mean yield of 0.07. Systematic measurements (TDS, UPS and XPS) reveal further details of the reaction chain associated with efficient thermal desorption of coronene oxides - a process analogous to the exfoliation of graphene oxide.