TY  - EJOUR
AU  - Haags, Anja
AU  - Reichmann, Alexander
AU  - Ruan, Zilin
AU  - Fan, Qitang
AU  - Egger, Larissa
AU  - Kirschner, Hans
AU  - Naumann, Tim
AU  - Werner, Simon
AU  - Kleykamp, Olaf
AU  - Martinez-Castro, Jose
AU  - Lüpke, Felix
AU  - Bocquet, François C.
AU  - Kumpf, Christian
AU  - Soubatch, Serguei
AU  - Gottwald, Alexander
AU  - Koller, Georg
AU  - Ramsey, Michael G.
AU  - Richter, Mathias
AU  - Sundermeyer, Jörg
AU  - Puschnig, Peter
AU  - Gottfried, J. Michael
AU  - Tautz, F. Stefan
AU  - Wenzel, Sabine
TI  - Multi-Orbital Charge Transfer into Nonplanar Cycloarenes Revealed with CO-Functionalized Tips
PB  - arXiv
M1  - FZJ-2025-03649
PY  - 2025
AB  - On-surface synthesis has allowed for the tuneable preparation of numerous molecular systems with variable properties. Recently, we demonstrated the highly selective synthesis of kekulene (>99%) on Cu(111) and isokekulene (92%) on Cu(110) from the same molecular precursor (Ruan et al., Angew. Chem. Int. Ed. 2025, e202509932). Scanning tunneling microscopy with CO-functionalized tips can identify the single molecules on the basis of their geometric structure at a low coverage on Cu(110), but it also detects complex features due to electronic contributions close to the Fermi energy. Here, we investigate the origin of these features by simulating STM images based on a weighted sum of multiple molecular orbitals, for which we employ weights based on the calculated molecular-orbital projected density of states. This allows for an experimental confirmation of charge transfer from the surface into multiple formerly unoccupied molecular orbitals for single molecules of kekulene as well as isokekulene in its two nonplanar adsorption configurations. In comparison, the area-integrating photoemission orbital tomography technique confirms the charge transfer as well as the high selectivity for the formation of a full monolayer of mainly isokekulene on Cu(110). Our STM-based approach is applicable to a wide range of adsorbed molecular systems and specifically also suited for strongly interacting surfaces, nonplanar molecules, and such molecules which can only be prepared at extremely low yields.
KW  - Chemical Physics (physics.chem-ph) (Other)
KW  - Materials Science (cond-mat.mtrl-sci) (Other)
KW  - FOS: Physical sciences (Other)
LB  - PUB:(DE-HGF)25
DO  - DOI:10.48550/ARXIV.2509.00736
UR  - https://juser.fz-juelich.de/record/1046002
ER  -