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 76.9: Talk
Wednesday, March 18, 2020, 17:30–17:45, WIL A317
Plasmonic K-Au nanoparticles from helium droplet synthesis — •Roman Messner1, Daniel Knez2, Ferdinand Hofer2, Wolfgang Ernst1, and Florian Lackner1 — 1Technische Universität Graz, Institut für Experimentalphysik, 8010-A — 2Technische Universität Graz, Institut für Elektronenmikroskopie und Nanoanalytik, 8010-A
We report on experiments on K-Au nanoparticles produced under UHV conditions by synthesis in helium nanodroplets. The particles are fabricated by coagulation of metal atoms after pickup by the cold droplets. The employed experimental techniques encompass in-situ spectroscopy as well as ex-situ investigations via transmission electron microscopy (TEM). Plain K clusters solvated in helium droplets exhibit a strong resonance at about 600 nm. The position of the resonance, thereby, depends on the K partial pressure in the pickup region, i.e. the size of the nanoparticles. After adding a gold shell-layer to the potassium particles, a blue shift of the resonance is observed, towards the well-known localized plasmon resonance of plain Au nanoparticles. An important aspect of our current research is to test the possibility of passivating the highly reactive K clusters with a Au shell, which would allow for the preparation of K-Au nanoparticle decorated substrates that can be investigated outside the UHV. First TEM investigations show promising results, opening up new perspectives for the production of novel material combinations for plasmonics with helium droplet based nanoparticle synthesis.