Near-field electron energy loss of nanotubes bundles and surface plasmons coupling in nanocylinders. A continuum dielectric approach

One of the most versatile formalism for the study of the electrodynamic response of solids, surfaces and interfaces or nanoparticles is the continuum dielectric model. In this contribution, we develop an application of this dielectric approach to nanocylinders and more particularly to the simulation of near-field electron energy loss (EEL) spectra of nanotube bundles. On the experimental side, EELS in a Scanning Transmission Electron Microscope (STEM) combines both spatial and energy resolutions in the plasmonic energy range and then permits the spectroscopic analysis of the surface and volume excitations of nanoparticles. Amongst the challenges brought about by the discovery of carbon nanotubes, one can cite the understanding of their optical properties. In this contribution, pursuing this goal within a dielectric continuum model, we focus on the dispersion and coupling of surface plasmon excitations of hollow nanocylinders and on the near-field EELS of nanotube nanocrystals (bundles). Experimental EELS in a STEM have also been obtained on bundles of carbon nanotubes. The interpretation in terms of effectif medium theory is successfuly performed both for surface and bulk losses associated with the sigma plasmon.