Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 31: Metal & Semiconductor substrates: Adsorption and reaction of small molecules – Poster
O 31.3: Poster
Monday, March 9, 2026, 18:00–20:00, P2
Quantitative imaging of surface potential of PTCDA molecules on Ag(111) and Pb(111) — •Sandhya Anchamkudy1, Janine Lorenz1,2, Amin Karimi1, Christian Wagner1,2, Ruslan Temirov1,3, Henry Thake4, Reinhard Maurer4, Stefan Tautz1,2, and Felix Lüpke1,3 — 1Peter Grünberg Institut (PGI 3), Forschungszentrum Jülich, Germany — 2Institut für Experimentalphysik IV A, RWTH Aachen, Germany — 3Institute of Physics II, Universität zu Köln, Germany — 4Department of Chemistry, University of Warwick, United Kingdom
Scanning Quantum Dot Microscopy (SQDM) enables quantitative imaging of surface dipoles with unprecedented energy and spatial resolution. In the past, SQDM has been applied to molecular adsorbates, adatoms, defects, and atomic assemblies on silver [Phys. Rev. Lett. 115, 026101 (2015), Nat. Mater. 18, 853 (2019)] - and provided valuable benchmarks for theory where metal-organic hybrid systems are particularly challenging. Here, we investigate the adsorption geometry dependent effects of isolated perylene tetracarboxylic dianhydride (PTCDA) molecules on Ag(111). We identified two preferred orientations of PTCDA molecules: along the <1-10> and <11-2> directions of the Ag(111) surface. In SQDM measurements, the two orientations yield distinct dipole moments of -0.51 D and -0.65 D, respectively. In addition, we carried out SQDM of a single PTCDA molecule on superconducting Pb(111) and found that the dipole is seven times larger compared to PTCDA on Ag(111). This difference can be attributed to a significantly higher charge transfer and adsorption height on Pb(111).
Keywords: SPM; SQDM; Surface potential mapping; Metal-organic systems; Superconductors