Excitation dependent Fano-like interference effects in plasmonic silver nanorods
American Physical Society
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Collins, S., Nicoletti, O., Rossouw, D., Ostasevicius, T., & Midgley, P. (2014). Excitation dependent Fano-like interference effects in plasmonic silver nanorods. https://doi.org/10.1103/PhysRevB.90.155419
Surface plasmon resonances in metal nanoparticles are an emerging technology platform for nano-optics applications from sensing to solar energy conversion. The electromagnetic near field associated with these resonances arises from modes determined by the shape, size, and composition of the metal nanoparticle. When coupled in the near field, multiple resonant modes can interact to give rise to interference effects offering fine control of both the spectral response and spatial distribution of fields near the particle. Here, we present an examination of experimental electron energy loss spectroscopy (EELS) of silver nanorod monomer surface plasmon modes and present an explanation of observed spatial amplitude modulation of the Fabry-Pérot resonance modes of these silver nanorods using electrodynamics simulations. For these simulations, we identify differences in spectral peak symmetry in light scattering and electron spectroscopies (EELS and cathodoluminescence) and analyze the distinct near-field responses of silver nanorods to plane-wave light and electron beam excitation in terms of a coupled oscillator model. Effects of properties of the material and the incident field are evaluated, and the spatially resolved EELS signals are shown to provide a signature for assessing Fano-like interference effects in silver nanorods. These findings outline key considerations and challenges for interpreting electron microscopy data on plasmonic nanoparticles for understanding nanoscale optics and for characterization and design of photonic devices.
EELS (electron energy loss spectroscopy), Plasmons on surfaces and interfaces, Optical properties of Nanocrystalline materials, Theory and models of optical properties
S.M.C. acknowledges support of a Gates Cambridge Scholarship. D.R. acknowledges support from the Royal Society's Newton International Fellowship scheme. We acknowledge the use of computing facilities provided by CamGrid. Parts of this work were also performed using the Darwin Supercomputer of the University of Cambridge High Performance Computing Service (http://www.hpc.cam.ac.uk/), provided by Dell Inc. using Strategic Research Infrastructure Funding from the Higher Education Funding Council for England and funding from the Science and Technology Facilities Council. We thank F.J. de la Peña for helpful discussions on the use of hyperspy. The research leading to these results has received funding from the European Research Council under the European Union's Seventh Framework Program (Grant No. FP7/2007-2013)/ERC Grant Agreement No. 291522-3DIMAGE. Data on rod “B” were acquired by one of us (D. Rossouw) with support of a NSERC Discovery Grant (G. A. Botton) at the Canadian Centre for Electron Microscopy, a national facility supported by NSERC and McMaster University. We thank G. A. Botton for access to data on rod “B” and for helpful comments on this manuscript. P.A.M. also acknowledges funding from the European Union's Seventh Framework Program under a contract for an Integrated Infrastructure Initiative (Reference No. 312483-ESTEEM2).
European Research Council (291522)
EC FP7 CP WITH CSA (312483)
External DOI: https://doi.org/10.1103/PhysRevB.90.155419
This record's URL: https://www.repository.cam.ac.uk/handle/1810/246153