Berlin 2012 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 17: Plasmonic Systems
HL 17.2: Vortrag
Montag, 26. März 2012, 15:15–15:30, EW 203
Near-field Study on Plasmonic Oligomers — •Thorsten Weber1,2, Felix von Cube1,2, Stephan Irsen2 und Stefan Linden1,3 — 1Physikalisches Institut, Universität Bonn, Nußallee 12, 53113 Bonn, Germany — 2Research center caesar, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany — 3Intitut für Nanotechnologie, Karlsruher Institut für Technologie (KIT), 76021 Karlsruhe, Germany
Plasmonic nano-structures have recently been proposed to be a useful tool in sensing. The corresponding sensors are based on the spectral shift of a mode of the plasmonic nano-structure upon change of the refractive index of the surrounding medium. The interaction of metallic nano-particles, arranged in an oligomer-like structure, gives rise to Fano resonances. The small spectral width of the Fano resonance makes plasmonic oligomers an interesting candidate for sensing applications. Furthermore, Fano resonances can easily be tuned in frequency by rearranging the oligomer's nano-particles in space or size. So far, interactions of the oligomer's particles have been mainly studied in optical far-field-measurements.
We employ electron energy loss spectroscopy in combination with scanning transmission electron microscopy to map the near-field of plasmonic oligomer structures for different energies. Our experiments give us a remarkable insight into the near-field interactions between the different particles of the oligomer. We study heptamers, which are six particles arranged around one central particle. Dissecting these into single particles, dimers, trimers, and hexamers allows a systematic study of how the separated parts of an oligomer interact.