Surface plasmon modes of a single silver nanorod: an electron energy loss study

TL;DR

This study uses electron energy loss spectroscopy to investigate surface plasmon modes in a single silver nanorod, revealing quantized resonant modes with spatially varying intensity and the importance of retardation and substrate effects in modeling.

Contribution

It provides detailed spatially resolved measurements of plasmon modes and highlights the need to include retardation and substrate effects in theoretical models.

Findings

Resonant plasmon modes vary along the nanorod's length.

Wavelengths of modes compress towards the nanorod ends.

Including retardation and substrate effects improves model accuracy.

Abstract

We present an electron energy loss study using energy filtered TEM of spatially resolved surface plasmon excitations on a silver nanorod of aspect ratio 14.2 resting on a 30 nm thick silicon nitride membrane. Our results show that the excitation is quantized as resonant modes whose intensity maxima vary along the nanorod's length and whose wavelength becomes compressed towards the ends of the nanorod. Theoretical calculations modelling the surface plasmon response of the silver nanorod-silicon nitride system show the importance of including retardation and substrate effects in order to describe accurately the energy dispersion of the resonant modes.