Plasmon excitations in carbon nanotubes

Electron-energy-loss spectroscopy (EELS) in a high-resolution transmission electron microscope can be used to study the excitation of plasmons in nanometre-size particles with high spatial resolution. For isotropic particles of various shapes, models which allow the attribution of the experimental peaks to a certain excitation mechanism and to understand sizeor geometry-dependent variations are well established. Recently, locally anisotropic particles such as nested concentric-shell fullerenes and carbon nanotubes have been discovered and have attracted considerable interest. The plasmon losses of these anisotropic particles measured by EELS could contribute to a better understanding of their physical properties, once the theoretical basis for the interpretation is adapted for anisotropic particles. Encouraged by very good qualitative agreement between a model of the plasmons of nested concentricshell fullerenes based on non-relativistic local dielectric response theory with experimental data, we present here a model for the plasmon excitations of multiwall carbon nanotubes based on the same theoretical approach. }