Spatially resolved measurements of plasmonic eigenstates in complex-shaped, asymmetric nanoparticles: Gold nanostars
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. © 2011 EDP Sciences. ; The authors acknowledge financial support from the European Union (E4) under the Framework 6 Program under a contract for an Integrated Infrastructure Initiative (reference 026019 ESTEEM), EU-FP6 (NMP4-2006-016881SPANS) and Marie Curie Program (MEST CT 2004 514307). ; Peer Reviewed