Plasmon electron energy-gain spectroscopy

Abstract

We explore multiple energy losses and gains undergone by swift electrons interacting with resonant evanescent light fields. We predict remarkably high gain probabilities in the range of a percentage when the electrons are passing near a resonant plasmonic structure under continuous-wave illumination conditions with moderate laser intensities ∼ 108 W m -2. Additionally, we observe fine structure in the dependence of the gain and loss probabilities on the light wavelength, which reveals a complex interplay between multiple plasmon-electron interactions. These results constitute a solid basis for the development of a new spectroscopy technique based upon the analysis of energy gains, capable of rendering information on the optical properties of the sampled resonant nanostructures. We illustrate this concept for plasmon-supporting noble metal nanoparticles. © IOP Publishing and Deutsche Physikalische Gesellschaft.