3D Imaging of Gap Plasmons in Vertically Coupled Nanoparticles by EELS Tomography

Georg Haberfehlner, Franz Schmidt, Gernot Schaffernak, Anton Hörl, Andreas Trügler, Andreas Hohenau, Ferdinand Hofer, Joachim Krenn, Ulrich Hohenester, Gerald Kothleitner

Research output: Contribution to journalArticle

Abstract

ABSTRACT:Plasmonic gap modes provide the ultimateconfinement of opticalfields. Demanding high spatialresolution, the direct imaging of these modes was onlyrecently achieved by electron energy loss spectroscopy (EELS)in a scanning transmission electron microscope (STEM).However, conventional 2D STEM-EELS is only sensitive tocomponents of the photonic local density of states (LDOS)parallel to the electron trajectory. It is thus insensitive tospecific gap modes, a restriction that was lifted with the introduction of tomographic 3D EELS imaging. Here, we show that by3D EELS tomography the gap mode LDOS of a vertically stacked nanotriangle dimer can be fully imaged. Besides probing thecomplete mode spectrum, we demonstrate that the tomographic approach allows disentangling the signal contributions from thetwo nanotriangles that superimpose in a single measurement with afixed electron trajectory. Generally, vertically couplednanoparticles enable the tailoring of 3D plasmonicfields, and their full characterization will thus aid the development of complexnanophotonic devices.
Original languageEnglish
Pages (from-to)6773-6777
JournalNano Letters
Volume2017
Issue number17
DOIs
Publication statusPublished - 2017

ASJC Scopus subject areas

  • Materials Science(all)

Fields of Expertise

  • Advanced Materials Science

Treatment code (Nähere Zuordnung)

  • Application

Cooperations

  • NAWI Graz

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