Berlin 2018 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 27: Graphene: Electronic properties, structure and substrate interaction II (joint session O/TT)
O 27.3: Vortrag
Dienstag, 13. März 2018, 11:15–11:30, MA 043
Polycyclic molecules with geometrical frustration via pyrolysis on a metal — •Alexandre Artaud1, Laurence Magaud2, Kitti Ratter3, Bruno Gilles3, Valérie Guisset2, Philippe David2, Jose I. Martinez4, Jose A. Martin-Gago4, Claude Chapelier5, and Johann Coraux2 — 1Institut für Experimentelle und Angewandte Physik, Christian-Albrechts Universität zu Kiel, Germany — 2CNRS, Institut Néel, Grenoble, France — 3Grenoble INP, SIMAP, Grenoble, France — 4Materials Science Factory, Instituto de Ciencia de Materiales de Madrid-CSIC, Madrid, Spain — 5CEA, INAC, PHELIQS, Grenoble, France
The geometry of molecules is a key to several of their properties. In graphene fragments, electron delocalization from one carbon sublattice to the other is frustrated for molecular shapes breaking the balance of sublattices. Optical, electronic, and magnetic properties emerge in this case, but the synthesis of such molecules remains challenging.
Here, a pyrolysis reaction catalysed by the surface of rhenium is investigated using scanning tunneling microscopy and density functional theory. This reaction known to form graphene is found to also yield graphene fragments consisting of well-defined, zigzag-edged polycyclic molecules, some of which have sublattice imbalance. However, they are found in metastable configurations, which is interpreted as a kinetic rather than thermodynamic control of their formation. Hence, metastable molecules are expectedly ubiquitous in graphene growth, and deleterious to achieve perfect graphene. Pyrolysis is conversely a promising route towards molecules with sought-after properties.