Berlin 2024 – scientific programme
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O: Fachverband Oberflächenphysik
O 72: Poster: Scanning Probe Microscopy: Light Matter Interaction at Atomic Scales
O 72.13: Poster
Wednesday, March 20, 2024, 18:00–20:00, Poster D
Probing Deformations of Heptahelicene Molecules via TERS — •Amandeep Sagwal1,2, Rodrigo Cezar De Campos Ferreira1, Jiří Doležal1,3, and Martin Švec1,4 — 1Institute of Physics, Czech Academy of Sciences; Czech Republic — 2Faculty of Mathematics and Physics, Charles University; Czech Republic — 3Institute of Physics, École Polytechnique Fédérale de Lausanne; Switzerland — 4Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences; Czech Republic
The Raman scattering from single molecules can be substantially enhanced by placing them within the nanocavity between a sharp plasmonic tip and sample using the Tip-Enhanced Raman Spectroscopy (TERS) technique [1][2]. TERS in ultrahigh vacuum and cryogenic conditions can also reveal the relations between adsorption geometry, electronic states, and vibrational modes of single molecules [3]. Here we study the behaviour of heptahelicene (BA7H) molecules on Ag (111) showing two different conformers i.e. so-called bright and dark [4]. TERS measurements are conducted using a laser with wavelength 633 nm, along with the lifting of molecules from the substrate. We observe significant energy shifts in the Raman peaks corresponding to the geometrical changes of the molecules and attempt to assign them to the normal vibrational modes of the molecules calculated by TD-DFT. [1] Lee, J., Crampton, K.T., Tallarida, N. et al. Nature 568, 7882 (2019). [2] Jaculbia, R. B. et al. Nat. Nanotechnol. 15, 105110 (2020). [3] R. C. de Campos Ferreira, et al. arXiv:2310.12546, (2023) [4] O. Stetsovych, J. Am. Chem. Soc., 140, 3, 940946 (2018)
Keywords: TERS; SPM; Helicene; vibrational modes