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O: Fachverband Oberflächenphysik

O 2: Organic Molecules on Inorganic Substrates I: Electronic, Optical and Other Properties I

O 2.1: Talk

Monday, March 27, 2023, 10:30–10:45, CHE 89

Hooke's law in a molecular spring: An nc-AFM and STM study of nonahelicene on Ag(110) — •Max Halbauer¹, Takashi Kumagai², Martin Wolf¹, and Akitoshi Shiotari¹ — ¹Fritz-Haber-Institute of the Max-Planck-Society, Faradayweg 4-6, 14195 Berlin, Germany — ²Institute for Molecular Science, 38 Nishigo-Naka, Myodaiji, 444-8585 Okazaki, Japan

Helicenes are a class of conjugated aromatic molecules representing macroscopic springs on the molecular scale. However, experimental insights on their mechanical properties remain scarce. This contribution employs scanning tunneling microscopy (STM) and noncontact atomic force microscopy (nc-AFM) measurements (UHV, liq. He) in order to address this issue. Frequency shift-distance traces were acquired on individual nonahelicene molecules and a planar reference molecule (coronene) and converted subsequently to force-distance curves. Model-functions accounting for the elasticity of the molecule were fitted to the data, which yielded the spring-constant - k - for elongation of nonahelicene. This work shows therefore that Hooke's law can be verified on the single-molecule scale by nc-AFM.