Plasmons of Hexamer and Pentamer Nanocavities Probed with Swift Electrons

Electron energy-loss spectroscopy (EELS) is an efficient tool for investigating the local density of optical states in single and coupled nano-systems in a transmission electron microscope (TEM) [1]. In EELS, a relativistic electron inelastically interacts with a sample, and hence loses energy by pumping the sample to a higher photonic state. The amount of energy loss of the electron is detected, providing us with information about the resonant energies of the sample. Mapping EELS by parallel acquisition, energy-filtered transmission electron microscopy (EFTEM) is a fast and efficient detection tool for mapping the optical modes in two spatial dimensions. Here, this is made possible by the in-column MANDOLINE energy filter in the Zeiss SESAM microscope [2].