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O: Fachverband Oberflächenphysik

O 71: Poster: Plasmonics and Nanooptics

O 71.18: Poster

Mittwoch, 20. März 2024, 18:00–20:00, Poster D

Decoding the Emission from Gold Nanoparticles — •Jan Kutschera, Wouter Koopman, Felix Stete, and Matias Bargheer — University of Potsdam

Surface-enhanced Raman spectroscopy (SERS) has been a valuable tool in biochemical sensing, single-molecule detection, and photocatalysis for several decades. The molecular fingerprints in SERS spectra are always accompanied by a broad background originating from the plasmonic nanoparticles themselves.

In particular, highly clustered nanoparticles, as used in many applications, can produce strong backgrounds. Due to its dependence on the electron distribution of the plasmonic material, understanding this nanoparticle response is crucial for comprehending the mechanisms behind plasmon-enhanced phenomena, such as photochemistry, photovoltaics, and magnetism. While the discussion regarding the underlying processes of this nanoparticle response is ongoing, it is most often attributed to photoluminescence (PL) or electronic Raman scattering (ERS) and thus to intraband processes.

Especially for gold nanoparticles, the contribution of interband transitions must be considered. Utilizing photoluminescence excitation (PLE) spectroscopy, we show the strong dependence on interband excitation, while the emission spectrum continues to be determined by plasmon-enhanced intraband processes. Furthermore, the presented results support the theory of interband-enabled, Auger-like excitations in the conduction band of gold, followed by intraband emissions in the visible spectrum.

Keywords: SERS; interband; plasmonics; photoluminescence; nanoparticle