Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 83: Organic molecules on inorganic substrates: electronic, optical and other properties III
O 83.2: Talk
Thursday, March 12, 2026, 15:15–15:30, HSZ/0201
Probing pi-conjugation in functionalized pentacene via photoemission orbital tomography — Felix Otto1, Andrei Matestskii2, Maximilian Schaal1, Elise Fürch1, Jonas Brandhoff1, Roman Forker1, François C. Bocquet2, Michael G. Ramsey3, Serguei Soubatch2, •Peter Puschnig3, Frank Stefan Tautz2, and Torsten Fritz1 — 1Institute of Solid State Physics, Friedrich Schiller University Jena, Germany — 2PGI-3, FZ Jülich & RWTH Aachen University, Germany — 3Institute of Phyics, University of Graz, Austria
Tuning the electronic structure of polycyclic aromatic hydrocarbons is an effective route to control their physical and chemical properties. Here, we present an experimental approach that enables direct assessment of how chemical functionalization modifies the conjugation length of adsorbed molecules. We demonstrate the method using pentacenequinone (P2O), a functionalized pentacene derivative that forms a self-assembled monolayer on Ag(110), as confirmed by low-energy electron diffraction and scanning tunneling microscopy. Employing photoemission orbital tomography, we combine experimental photoelectron momentum maps with density-functional-theory simulations to elucidate the character of the frontier molecular orbitals. Our results provide direct experimental evidence that the functional group in P2O disrupts the conjugation of the parent pentacene backbone, causing the electronic structure of P2O to resemble two electronically decoupled naphthalene units. This interpretation is further supported by the observed increase in the band gap upon functionalization.
Keywords: chemical functionalization; photoemission orbital tomography; conjugation length