Strong and Weak Coupling Nanophysics with Free Electron Beams

The work of Luis M. Liz‐Marzán, his colleagues, and other nanochemists has been essential in the emergence of electron spectroscopies for nano‐optics applications. After a brief presentation of these techniques and their applications to individual plasmonic nanoparticles, this paper focuses on a short review of the study of the coupling between optical excitations at the nanometer scale, made possible by recent advances in electron spectroscopies. In particular, plasmon–plasmon, plasmon–exciton, and plasmon–phonon couplings are reviewed.