Dresden 2020 – scientific programme
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O: Fachverband Oberflächenphysik
O 76: Plasmonics and Nanooptics V: Tunable Structures and Nanoparticles (joint session O/CPP)
O 76.10: Talk
Wednesday, March 18, 2020, 17:45–18:00, WIL A317
Synthesis of plasmonic Ag@ZnO core@shell nanoparticles inside superfluid helium droplets — •Alexander Schiffmann1, Thomas Jauk1, Daniel Knez2, Harald Fitzek2, Ferdinand Hofer2, Florian Lackner1, and Wolfgang E. Ernst1 — 1Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria — 2Institute of Electron Microscopy and Nanoanalysis & Graz Centre for Electron Microscopy, Graz University of Technology, Steyrergasse 17, A-8010 Graz, Austria
Plasmonic Ag@ZnO core@shell nanoparticles in the sub 10 nm size regime have been synthesized in a unique way by employing the helium nanodroplet approach. A peculiarity of this low temperature technique, where the particles are formed within a superfluid helium environment, is the complete absence of solvents and surfactants. Scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS) give insight into the composition and structure of the particles, revealing a very uniform thickness and shape of the ZnO shells surrounding the Ag cores. The oxidation state of the shell was investigated by ultraviolet photoelectron spectroscopy (UPS). Photoelectron spectra of Ag@ZnO, ZnO, and Ag nanoparticles have been recorded by two-photon photoelectron (2PPE) spectroscopy. The employed laser with a photon energy of 3 eV is resonant to the localized surface plasmon in Ag. In the case of Ag and Ag@ZnO an excitation of this plasmon gives rise to an increased yield of electrons with high kinetic energy.