The atom-scale spatial resolution and few meV spectral resolution available in monochromated and aberration-corrected scanning transmission electron microscopes (STEMs) is opening new frontiers for fast electron spectroscopies. Herein we examine the coupling of localized surface plasmons in individual nanofabricated disk-rod dimers. By manipulating the interparticle spacing and rod polarizability, we interpolate between and characterize both regimes using a combination of STEM electron energy-loss spectroscopy (EELS) and theoretical modeling. We find that spectrally narrow, infrared plasmonic Fano antiresonances emerge in the limit of weak coupling that evolve into hybridized normal modes in the most strongly coupled dimers. This work illustrates that ultra low-loss STEM-EELS is now capable of experimentally observing nanoscale plasmonic responses that were previously the domain only of higher resolution optical spectroscopies.

Using STEM/EELS to image energy transfer processes in plasmonic nanostructures: Nanodimers spanning the gap between weak and strong coupling

2019 Fall National Meeting

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