1. Synthesis and characterization of super-nonazethrene
- Author
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Turco, Elia, Mishra, Shantanu, Melidonie, Jason, Eimre, Kristjan, Obermann, Sebastian, Pignedoli, Carlo A., Fasel, Roman, Feng, Xinliang, and Ruffieux, Pascal
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter - Materials Science - Abstract
Beginning with the early work of Clar et al. in 1955, zethrenes and their laterally-extended homologues, super-zethrenes, have been intensively studied in the solution phase, and are widely investigated as optical and charge transport materials. Super-zethrenes are also considered to exhibit an open-shell ground state. Zethrenes may thus serve as model compounds to investigate nanoscale pi-magnetism. However, their synthesis is extremely challenging due to their high reactivity. We report here a combined in-solution and on-surface synthesis of the hitherto largest zethrene homologue - super-nonazethrene - on Au(111). Using single-molecule scanning tunneling microscopy and spectroscopy, we show that super-nonazethrene exhibits an open-shell singlet ground state featuring a large spin polarization-driven electronic gap of 1 eV. We obtain real-space maps of the frontier molecular orbitals, and find that they correspond to singly occupied molecular orbitals. In consistence with the emergence of an open-shell ground state, high-resolution tunneling spectroscopy reveals inelastic singlet-triplet spin excitations in super-nonazethrene, characterized by a strong intramolecular magnetic exchange coupling of 51 meV. Further insights are gained by mean-field and many-body perturbation theory calculations. Given the paucity of zethrene chemistry on surfaces, our results therefore provide unprecedented access to large open-shell zethrene compounds amenable to scanning probe measurements, with potential application in molecular spintronics., Comment: 7 pages, 4 main figures and 1 Table of Contents artwork; supplementary information containing additional data is included
- Published
- 2021
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