Regensburg 2025 – scientific programme

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O: Fachverband Oberflächenphysik

O 20: Poster Scanning Probe Microscopy: Light-Matter Interactions at the Atomic Scale

O 20.11: Poster

Monday, March 17, 2025, 18:00–20:00, P2

Resonant energy transfer as a function of distance between metal-phthalocyanine molecules — •Roel Burgwal, Nikhil Seeja Sivakumar, Joëlle J. A. Schrijer, Alexander A. Khajetoorians, and Daniel Wegner — Institute for Molecules and Materials, Radboud University, 6500 GL Nijmegen, The Netherlands

Resonant transfer of energy (RET) between molecules is a process ubiquitous in nature that also has interesting technological applications. The rate of RET decreases as the molecules involved are spaced further apart, with the distance dependence determined by the exact mechanism responsible for energy transfer. Two possible mechanisms are electrodynamical Förster energy transfer (FRET) and the electron tunneling-based Dexter energy transfer (DET). Recent advances in scanning tunneling microscope-induced luminescence (STML) have made it possible to observe energy transfer between single molecules and to control the spacing between these with sub-nanometer precision. So far, STML measurements of RET distance dependence resemble more the exponential behavior of DET, in contrast with the commonly assumed FRET mechanism. However, it has been proposed this apparent behavior may be a plasmonic effect arising from the varying distance between STML-tip and acceptor molecule. Here, we study RET between different metal-phthalocyanine molecules while elucidating the role of the plasmon through complementary measurements.

Keywords: Scanning tunneling microscopy; Luminescence; Resonant energy transfer; Plasmonics; Molecules