Imaging of plasmonic modes of silver nanoparticles using high-resolution cathodoluminescence spectroscopy.

Chaturvedi, Pratik; Hsu, Keng H; Kumar, Anil; Fung, Kin Hung; Mabon, James C; Fang, Nicholas X · ACS Nano · 2009

basic_science · Level V

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Abstract

Cathodoluminescence spectroscopy has been performed on silver nanoparticles in a scanning electron microscopy setup. Peaks appearing in the visible range for particles fabricated on silicon substrate are shown to arrive from excitation of out-of-plane eigenmodes by the electron beam. Monochromatic emission maps have been shown to resolve spatial field variation of resonant plasmon mode on length scale smaller than 25 nm. Finite-difference time-domain numerical simulations are performed for both the cases of light excitation and electron excitation. The results of radiative emission under electron excitation show an excellent agreement with experiments. A complete vectorial description of induced field is given, which complements the information obtained from experiments.