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O: Fachverband Oberflächenphysik
O 40: Organic Molecules on Inorganic Substrates III: Electronic, Optical and other Properties
O 40.2: Vortrag
Dienstag, 17. März 2020, 10:45–11:00, REC C 213
Energy levels and charge distribution within dipolar molecules on MoS2/Au(111) — •Sergey Trishin1, Daniela Rolf1, Christian Lotze1, Johanna Richter1, Philipp Rietsch2, Siegfried Eigler2, and Katharina J. Franke1 — 1Fachbereich Physik, Freie Universität Berlin — 2Institut für Chemie und Biochemie, Freie Universität Berlin
Molecules consisting of a donor and an acceptor moiety can exhibit large intrinsic dipole moments. Upon deposition on a metal surface, the dipole may be effectively screened and the charge distribution altered due to hybridization with substrate electronic states. Therefore, the inclusion of a thin band-gapped material can help to preserve gas-phase-like electronic properties. We study Ethyl-Diaminodicyanoquinone molecules on a Au(111) surface and on single-layer molybdenum disulfide (MoS2) on Au(111) with scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM). By mapping the local contact potential difference (LCPD) over the molecules we show that the intrinsic dipole moment of the molecules is partially preserved upon adsorption on both the bare Au(111) surface and MoS2. On Au(111), the molecular resonances show an apparent shift in energy within individual molecules. The high energy resolution on molecules adsorbed on MoS2 allows us to conclude that the apparent shift is due to several resonances of varying intensity, arising from vibronic states. DFT calculations of the molecule in gas phase help to identify certain vibrations of the molecule from their signature in the tunneling spectra.