Eur. Phys. J. Appl. Phys. 54, 33512 (2011)
https://doi.org/10.1051/epjap/2011100443

Spatially resolved measurements of plasmonic eigenstates in complex-shaped, asymmetric nanoparticles: gold nanostars

¹ Laboratoire de Physique des Solides, Bâtiment 510, CNRS/UMR 8502, Univ Paris Sud 11, 91405 Orsay, France
² Departamento de Química Física, and Unidad Asociada CSIC-Universidade de Vigo, 36310 Vigo, Spain
³ Instituto de Optica, CSIC, Serrano 121, 28006 Madrid, Spain

^a mathieu.kociak@u-psud.fr

Received: 2 November 2010
Revised: 28 February 2011
Accepted: 17 March 2011
Published online: 13 June 2011

Abstract

We report on spatially resolved electron energy-loss spectroscopy studies of optical modes in individual star-shaped gold nanoparticles. We studied different morphologies, ranging from a spheroid to well-developed nanostars. For each shape, essentially two groups of modes are appearing: the first one is localized around the core of the nanostars and has an energy slightly less than the quasi-static dipolar mode of a gold sphere (about 2.2 eV); in the second group, the modes are localized at the end of the nanostar tips, with varying energies depending on the geometry of each tip and with energy down to 1.2 eV. The localization of the tip modes is interpreted with the help of boundary element methods simulations.