Berlin 2018 – scientific programme
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O: Fachverband Oberflächenphysik
O 64: Focus Session: Molecular Nanostructures on surfaces - New Concepts towards Complex Architectures IV
O 64.8: Talk
Wednesday, March 14, 2018, 17:00–17:15, MA 004
Probing intermolecular interactions in a molecular layer via single-molecule manipulation — •Christian Wagner1,2, Philipp Leinen1,2, Alexander Diener1,2, Ruslan Temirov1,2, and F. Stefan Tautz1,2 — 1Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, Germany — 2Jülich Aachen Research Alliance (JARA)-Fundamentals of Future Information Technology, Jülich, Germany
Adsorption of large organic molecules is often influenced by their functional groups which may simultaneously interact with the surface and neighboring molecules. Together with the mechanical flexibility of molecules this leads to a multidimensional, highly structured and typically rather shallow interaction potential landscape which can hardly be investigated by any other means than theoretical simulations. Here we show that non-contact atomic force microscopy (NC-AFM) facilitates single-molecule manipulation protocols which enable probing the potential energy surface in a molecular layer. We apply the manipulation to the archetypal model system PTCDA (perylene-3,4,9,10-tetracarboxylic dianhydride) on Ag(111) and study the influence of polar groups, specifically of weak hydrogen bonds on the intermolecular potential. Fitting a force-field model to our experimental data reveals how electrostatic interactions cause out-of-plane forces on partially charged atoms. Our results intuitively explain how such interactions can alter the vertical adsorption geometry of a molecule in a layer compared to an isolated molecule.