Dresden 2026 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 43: Scanning probe microscopy: light matter interaction at atomic scales – Poster
O 43.7: Poster
Dienstag, 10. März 2026, 14:00–16:00, P2
Photo-switching of azobenzene derivatives on Au(111) — •Matthew J. Timm1, Robert di Vora2, Stefan Hecht3, Birgitta Bernhardt2, and Leonhard Grill1 — 1Institute of Chemistry, University of Graz, Austria — 2Institute of Experimental Physics, Graz University of Technology, Austria — 3Department of Chemistry & IRIS Adlershof, Humboldt-Universität zu Berlin, Germany
The light-induced trans-cis isomerization of azobenzene and its derivatives is of great scientific and technological interest as these molecular photo-switches can be used for nano-scale sensing or information storage. Particularly, 3,3',5,5'-tetra-tert-butylazobenzene (mTBA) adsorbed upon Au(111) has seen much interest, being studied at sub-monolayer coverage (around 0.1 ML) by scanning tunneling microscopy (STM) [1,2] and near monolayer (ML) coverage (0.9 ML) by two-photon photoemission [3]. However, missing is a single-molecule level insight into whether photo-switching at low coverage differs from that at higher but still sub-monolayer coverage - does it matter if only small or large areas of the surface are covered? Here, we combine STM with a self-designed computer-vision algorithm to study photoisomerization induced by pulsed laser radiation (λ = 518 nm) at a rather high surface coverage of 0.6 ML. This approach can track the isomerization state of thousands of individual mTBA molecules and enables us to detect subtle variations in switching yields among densely packed, similarly oriented molecules. [1] M. Alemani, et al. JACS 128 (2006) 14446. [2] M. J. Comstock, et al. Phys. Rev. Lett. 99 (2007) 038301. [3] S. Hagen, et al. Chem. Phys. Lett. 444 (2007) 85-90.
Keywords: Scanning Tunneling Microscopy; Computer Vision; Photo-switch; Light-matter interaction; Azobenzene