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O: Fachverband Oberflächenphysik
O 9: Organic molecules on inorganic substrates: electronic, optical and other properties I
O 9.8: Talk
Monday, March 9, 2026, 16:45–17:00, HSZ/0201
Optical characterisation of single chlorophyll molecules at the sub-nanometre scale — Thiago G. L. Brito1, •Daniel Arribas1, Myriam Wadsack1, Claudia Leticia Gómez Flores1, Victor Feitosa1, Klaus Kuhnke1, Klaus Kern1,2, Kelvin Anggara1, and Anna Rosławska1 — 1Max Planck Institute for Solid State Research, Stuttgart, Germany — 2École Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
As one of the main biomolecules harvesting light in photosynthetic organisms, chlorophyll plays a crucial role in biological systems, ultimately sustaining life on Earth. Therefore, the fundamental understanding of its optical properties has attracted widespread interest from the scientific community. However, traditional spectroscopic experiments, often probing complexes, only provide an averaged understanding of the rich photophysics of chlorophyll, where the effects of each possible molecular configuration and the local environment are smeared out. In this work, we address this by exploiting the sub-nm resolution of scanning tunnelling microscopy and the highly-localised plasmonic enhancement of the picocavity in the tunnelling junction. We characterise individual chlorophyll molecules, deposited by electrospray ion beam deposition on a Ag(111) surface with NaCl islands as decoupling layer. By analysing the fluorescence emission excited by the tunnelling electrons, we observe the structural dependency of the molecular opto-electronic properties. Our investigation opens new opportunities for the fundamental understanding of light-harvesting during photosynthesis with unprecedented sub-molecular resolution.
Keywords: Chlorophyll; Scanning Tunnelling Microscopy (STM); Scanning Tunneling Microscopy Luminescence (STML); Plasmonic enhancement; Single Molecule Spectroscopy