Spontaneous and stimulated electron–photon interactions in nanoscale plasmonic near fields

• DOI: 10.1038/s41377-021-00511-y
• Publication Date: 2021-04-15T14:11:34Z
• Authors: Matthias Liebtrau; Murat Sivis; Armin Feist; Hugo Lourenço-Mar...; Nicolas Pazos-Pérez; Ramon A. Alvarez-...; F. Javier García ...; Albert Polman; Claus Ropers
• Keywords: Cathodoluminescence

We demonstrate spatially-resolved measurements of spontaneous and stimulated electron-photon interactions in nanoscale optical near fields using electron energy-loss spectroscopy (EELS), cathodoluminescence (CL), photon-induced near-field microscopy (PINEM). Specifically, we study resonant surface plasmon modes that are tightly confined to the tip apexes an Au nanostar, enabling a direct correlation EELS, CL, PINEM on same physical structure at nanometer length scale. Complemented by numerical electromagnetic boundary-element method calculations, discuss interaction strength spatial dependence our CL distributions. limit isolated mode, variations electron-near field coupling fully determined modal electric profile, irrespective (in EELS CL) or nature PINEM) process. Yet show crucially depends incident energy with maximum few keV, depending proximity apex. Our results provide elementary insights into electron-light-matter have key implications for research (quantum) coherent phenomena microscopy.