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O: Fachverband Oberflächenphysik
O 31: Focus Session Molecular Nanostructures on Surfaces: On-Surface Synthesis and Single-Molecule Manipulation II
O 31.2: Vortrag
Dienstag, 18. März 2025, 10:45–11:00, H24
Sliding friction over covalent bonds increases with bond order — Shinjae Nam1, Lukas Hörmann2,3, Oliver Gretz1, Oliver T. Hofmann2, Franz J. Giessibl1, and •Alfred J. Weymouth1 — 1Universität Regensburg, Regensburg, Deutschland — 2TU Graz, Graz, Österreich — 3The University of Warwick, Warwick, U.K.
Friction is governed by atomic-scale interactions, yet we lack a complete understanding of its working at this length scale. To address this, we reduce one sliding surface to the limit of a single atom and measure sliding friction with lateral force microscopy over single bonds. We examine islands of PTCDA on Cu(111), which present a rich variety of covalent and hydrogen bonds. There is a large variety in the maximum energy dissipation over different covalent bonds. The maximum energy dissipation over hydrogen bonds has similar values, although energy dissipation over hydrogen bonds is observed at lower heights than over covalent bonds. With DFT-based simulations and a machine-learning model, we determine that larger bond order is correlated to higher sliding friction.
Keywords: Lateral force microscopy; Atomic force microscopy; Tribology; Bond order