Fundamental Limit of Plasmonic Cathodoluminescence.

Franz-Philipp Schmidt,Michal Horák,Ulrich Hohenester,Arthur Losquin,Michael Stöger-Pollach,Joachim R Krenn

doi:10.1021/acs.nanolett.0c04084

Franz-Philipp Schmidt, Michal Horák + Show 4 more

Open Access

https://doi.org/10.1021/acs.nanolett.0c04084

Copy DOI

Abstract

We use cathodoluminescence (CL) spectroscopy in a transmission electron microscope to probe the radial breathing mode of plasmonic silver nanodisks. A two-mirror detection system sandwiching the sample collects the CL emission in both directions, that is, backward and forward with respect to the electron beam trajectory. We unambiguously identify a spectral shift of about 8 nm in the CL spectra acquired from both sides and show that this asymmetry is induced by the electron beam itself. By numerical simulations, we confirm the observations and identify the underlying physical effect due to the interference of the CL emission patterns of an electron-beam-induced dipole and the breathing mode. This effect can ultimately limit the achievable fidelity in CL measurements on any system involving multiple excitations and should therefore be considered with care in high-precision experiments.

Highlights

We use cathodoluminescence (CL) spectroscopy in a transmission electron microscope to probe the radial breathing mode of plasmonic silver nanodisks
As the electrons pass perpendicularly through a plasmonic silver nanodisk, slightly different charge densities are excited on both disk faces, generating a dipole moment aligned with the electron trajectory
Overlapping the plasmonic radial breathing mode (RBM) of the nanodisk, the far field interference of the CL patterns of these two modes leads to a distinct spectral shift of about 8 nm in the backward and forward directions with respect to the beam trajectory

Summary

Introduction

We use cathodoluminescence (CL) spectroscopy in a transmission electron microscope to probe the radial breathing mode of plasmonic silver nanodisks. Nano Letters pubs.acs.org/NanoLett spectra acquired in backward (red) and forward directions (blue).

Results

Conclusion