Far-Field Electron Spectroscopy of Nanoparticles

TL;DR

This paper predicts a new type of electron-induced excitations in nanoparticles, showing enhanced electromagnetic modes accessible via electron energy loss spectroscopy, bridging near-field and far-field optical phenomena.

Contribution

It introduces a novel theoretical prediction of far-field accessible electromagnetic modes in nanoparticles induced by focused electron beams, expanding understanding of electron-nanoparticle interactions.

Findings

Enhanced radiative electromagnetic modes within the light cone.

Breakdown of momentum conservation enables new excitations.

Potential for far-field optical applications using electron beams.

Abstract

A new type of excitations by highly focused electron beams in scanning transmission electron microscopes is predicted for nanoparticles. The calculated electron energy loss spectra of metallic (silver) and insulating (SiO(sub2)) nanoplatelets reveal dramatic enhancement of radiative electromagnetic modes within the light cone, allowed by the breakdown of momentum conservation in the inelastic scattering event. These modes can be accessed with e-beams in the vacuum far-field zone, similarly to the recently developed far-field optics based on surface plasmon resonances.