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On-Surface Synthesis and Determination of the Open-Shell Singlet Ground State of Tridecacene** |
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| Authors: | Rafal Zuzak Manish Kumar Otilia Stoica Diego Soler-Polo Jiri Brabec Katarzyna Pernal Libor Veis Remi Blieck Antonio M Echavarren Pavel Jelinek Szymon Godlewski |
| Institution: | 1. Centre for Nanometer-Scale Science and Advanced Materials, NANOSAM, Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, Lojasiewicza 11, 30348 Krakow, Poland;2. Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 16200 Prague, Czech Republic
These authors contributed equally to this work.;3. Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, 43007 Tarragona, Spain Departament de Quımica Organica i Analıtica, Universitat Rovira i Virgili, 43007 Tarragona, Spain These authors contributed equally to this work.;4. Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 16200 Prague, Czech Republic;5. Department of Theoretical Chemistry, J. Heyrovsky Institute of Physical Chemistry, Czech Academy of Sciences, 18200 Prague, Czech Republic;6. Institute of Physics, Lodz University of Technology, ul. Wolczanska 219, 90924 Lodz, Poland;7. Institute of Chemical Research of Catalonia (ICIQ), Barcelona Institute of Science and Technology, 43007 Tarragona, Spain |
| Abstract: | The character of the electronic structure of acenes has been the subject of longstanding discussion. However, convincing experimental evidence of their open-shell character has so far been missing. Here, we present the on-surface synthesis of tridecacene molecules by thermal annealing of octahydrotridecacene on a Au(111) surface. We characterized the electronic structure of the tridecacene by scanning probe microscopy, which reveals the presence of an inelastic signal at 126 meV. We attribute the inelastic signal to spin excitation from the singlet diradical ground state to the triplet excited state. To rationalize the experimental findings, we carried out many-body ab initio calculations as well as model Hamiltonians to take into account the effect of the metallic substrate. Moreover, we provide a detailed analysis of how the dynamic electron correlation and virtual charge fluctuation between the molecule and metallic surface reduces the singlet-triplet band gap. Thus, this work provides the first experimental confirmation of the magnetic character of tridecacene. |
| Keywords: | Diradicals Higher Acenes Inelastic Excitation Many-Body Calculations Open-Shell Compounds |