Experimental evidence of surface-plasmon coupling in anisotropic hollow nanoparticles

Phys Rev Lett. 2001 Aug 13;87(7):075501. doi: 10.1103/PhysRevLett.87.075501. Epub 2001 Jul 26.

Abstract

We report on the investigation of surface-plasmon excitation of anisotropic WS(2) hollow nanoparticles in a near-field geometry by means of a scanning transmission electron microscope. The shell thickness influence on the electron-energy-loss-spectroscopy spectra is experimentally observed and is analyzed within a classical dielectric formalism. As for the isotropic case, we evidence one symmetric (tangential) and one antisymmetric (radial) mode. We point out the intriguing fact that, for the anisotropic case, one can relate these modes to the interband transition of the in-plane component of the dielectric tensor and to the bulk-plasmon energy of the out-of-plane component.