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Title: Effect of multipole excitations in electron energy-loss spectroscopy of surface plasmon modes in silver nanowires

We have characterized the surface plasmon resonance (SPR) in silver nanowires using spatially resolved electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope. Non-symmetric EELS spectra due to high-k SPR propagation along the nanowire and spectral shifts due to higher-order mode excitation are observed when the beam is positioned near the tip of the nanowire. When the beam is far from the tip region and on the side of nanowire, no spectral shifts are observed as the beam is scanned in the radial direction of the nanowire. The experimental spectra are compared with three different theoretical approaches: direct numerical calculation of the energy loss, analytical models for energy loss, and numerical simulations using an optical model. All three models reproduce the spectral shifts as the electron beam approaches the cap of the nanowire. The analytical model reveals the origin of the shifts in high-order plasmon mode excitation.
Authors:
;  [1] ; ; ;  [2] ;  [3]
  1. Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States)
  2. Institut für Physk, Karl-Franzens-Universität Graz, 8010 Graz (Austria)
  3. Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)
Publication Date:
OSTI Identifier:
22402754
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 116; Journal Issue: 22; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPUTERIZED SIMULATION; ELECTRON BEAMS; ELECTRONS; ENERGY LOSSES; ENERGY-LOSS SPECTROSCOPY; EXCITATION; QUANTUM WIRES; SILVER; SPECTRAL SHIFT; SURFACES; TRANSMISSION ELECTRON MICROSCOPY