Dresden 2011 – scientific programme
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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.86: Poster
Wednesday, March 16, 2011, 17:30–21:00, P4
Near-and farfield investigations of individual sub-nanometre plasmonic gap resonances — •Florian Schertz1, Reza Mohammadi2, Marcus Schmelzeisen2, Hans-Joachim Elmers1, Gerd Schönhense1, and Max Kreiter2 — 1Inst. f. Physik, J. Gutenberg-Universität, Mainz — 2MPI f. Polymerforschung, Mainz
An increasing interest evolved on the mutual interaction of distinct plasmonic resonances during the last years, due to the extremely enhanced and localized electromagnetic fields that are provoked. Prominent examples are nanoparticle (NP) dimers with an ultrasmall gap between them or NPs close to metallic films, the latter can be manufactured with reproducible sub-nm gaps. These coupled plasmons supporting systems act as optical antennae, as they efficiently convert free-propagating radiation into localized electromagnetic energy. Hence, understanding the optical near-field (NF) and far-field (FF) properties is essential for a full understanding of nano-antennae and for application-oriented optimization. We present NF- and FF-spectra and corresponding SEM images of the same individual gap-resonance supporting Au NPs on a Au film with a gap of 0.8nm. Dark-field confocal microscopy is used for detection of the FF response, photoemission electron microscopy for the NF characteristics. Beside the well-known FF gap-resonances, additional dark-mode resonances were observed exclusively in the NF, depending strongly on the NP properties. The experimental findings are analyzed and systematized concerning their correlation to FIT-simulations of the optical NF and FF. Funded by DFG EL172-16.