Effect of multipole excitations in electron energy-loss spectroscopy of surface plasmon modes in silver nanowires
Andrew Herzing, Theodore Norris, Xiuli Zhou, Nestor Zaluzec
The surface plasmon (SP) response to an external electromagnetic field plays a dominant role in determining the optical properties of metallic nanostructures. We have characterized this response in silver nanowires using spatially resolved electron energy loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). Nearly periodic maxima were observed in the loss probability when the beam was directed near the side surface of the nanowires, while the spectral shifts due to the excitation of higher-order modes occurred when the beam was positioned near the tip of the NW. The experimental spectra are interpreted using both analytical results for energy loss of infinite nano-cylinders and nanospheres, and numerical simulations using an optical model. The analytical theories predict the observed spectra very well, once the finite energy resolution of the experimental system is included in the prediction. The optical models reproduce the observed EELS spectra semi-quantitatively; a discussion is presented on the limitations of each model for interpreting details of the experimental spectra.
, Norris, T.
, Zhou, X.
and Zaluzec, N.
Effect of multipole excitations in electron energy-loss spectroscopy of surface plasmon modes in silver nanowires, Journal of Applied Physics, [online], https://doi.org/10.1063/1.4903535
(Accessed October 2, 2023)