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O: Fachverband Oberflächenphysik

O 5: Scanning Probe Microscopy: Light-Matter Interactions at the Atomic Scale I

O 5.2: Vortrag

Montag, 17. März 2025, 10:45–11:00, H6

Plasmon-induced reaction in hydrogen-bonded molecular networks studied by laser-coupled STM — •Youngwook Park, Adnan Hammud, Martin Wolf, and Akitoshi Shiotari — Fritz Haber Institute of the Max Planck Society, Berlin, Germany

Hydrogen-bonded molecular networks are widely found in natural systems and play an important role in the development of functional molecular assemblies. Understanding chemical reactions within these networks requires molecular-level spatial resolution, which is challenging for photochemical studies. In this talk, we present a plasmon-induced reaction in 2D hydrogen-bonded assemblies, studied with a laser-coupled scanning tunneling microscope (STM). We investigated triphenylene-2,6,10-tricarboxylic acid forming a honeycomb network on Au(111) through hydrogen bonds. Our findings showed that photo-induced deformation of the network was localized to a few molecules beneath the Ag tip under visible laser illumination. In contrast, a PtIr tip, which lacks plasmonic activity in the visible range, failed to trigger the reaction. By varying the laser wavelength, we identified that non-thermal (hot) electrons generated by plasmons mediate the reaction. This was confirmed by initiating the reaction with non-thermal electrons from the STM tip without laser irradiation. Our results highlight the potential of plasmonic STM tips for precise control over molecular network structure and reactivity.

Keywords: plasmon chemistry; hydrogen bond; molecular assembly; photoreaction; hot electron