SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 76: Plasmonics and Nanooptics III: Light-Matter Interaction and Spectroscopy II

O 76.5: Vortrag

Donnerstag, 30. März 2023, 11:30–11:45, WIL A317

Photoluminescence mapping of an anionic molecule — •Jiří Doležal, Rodrigo Ferreira, Amandeep Sagwal, Petr Kahan, and Martin Švec — Institute of Physics, Czech Academy of Sciences; Cukrovarnická 10/112, CZ16200 Praha 6, Czech Republic

Only recently, the photoluminescence (PL) of a single molecule has been attained [1,2] with sub-nm resolution in a scanning tunneling microscope (STM). However, only a fluorescent peak from a neutral phthalocyanine has been observed. The observation of fluorescence from a charged molecule is still elusive, likely due to the plasmon-mediated excitation mechanism which is fundamentally different from the electroluminescence (EL) process where a charged exciton can be created via electron/hole tunneling into dication/dianion [3,4].

Here, we present STM-PL maps of PTCDA anion adsorbed on 3ML/NaCl. The anionic charge state of the adsorbed molecule [5] enables its direct excitation by a laser-induced gap plasmon. We show STM-PL photon maps of an individual molecule and small molecular clusters qualitatively comparable to STM-EL maps [5], but independent of the tunneling current. This brings a major advantage over electroluminescence as the current is a scaling factor in the photon map intensity and its elimination [5-7] creates unwanted artefacts.

[1] B. Yang et al. Nat. Photonics 14, 693 (2020). [2] H. Imada et al. Science 373, 95 (2021). [3] K. Kaiser et al. arXiv:2211.01051 (2022). [4] B. Doppagne et al. Science 361, 251 (2018). [5] J. Doležal et al. ACS Nano 16, 1082 (2022). [6] B. Doppagne et al. PRL 118, 127401 (2017). [7] Y. Zhang et al. Nature 531, 623 (2016).