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O: Fachverband Oberflächenphysik
O 6: Organic molecules on inorganic substrates: Adsorption and growth I
O 6.8: Talk
Monday, March 9, 2026, 12:15–12:30, TRE/PHYS
Competition between dative bonds and aromatic gains — •Jonas Brandhoff1, Richard Berger2, Felix Otto1, Maximilian Schaal1, Lorenz Brill1, Oliver T. Hofmann2, Peter Puschnig3, Torsten Fritz1, and Roman Forker1 — 1Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany — 2Institute of Solid State Physics, Technical University Graz, Petersgasse 16, 8010 Graz, Austria — 3Institute of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria
Upon molecular adsorption on a surface, a variety of interactions can occur. Identifying which mechanisms dominate this complex quantum-mechanical landscape is crucial for understanding molecule – surface coupling. One key factor in many π-conjugated systems is aromaticity – a fundamental concept in chemistry describing the energetic stabilization that arises from particular π-electron arrangements. To investigate how aromaticity competes with other adsorption-driven interactions, we study 5,7,12,14-pentacenetetrone (P4O) on different metal surfaces as a model system. P4O is a prototypical molecule expected to undergo aromatic stabilization upon adsorption, where charge transfer from the substrate modifies the topology of the occupied π-system and leads to a more energetically favorable configuration. Using photoemission orbital tomography measurements combined with density functional theory calculations, we show how hybridization with the surface can outweigh a potential aromatic stabilization, not necessarily maximizing the latter. We reveal a mechanism in which the unoccupied π-system of the molecule forms dative bonds with the substrate.
Keywords: POT; DFT; STM