title: Ultralocal modification of surface plasmons properties in silver nanocubes.
abstract: The plasmonic properties of individual subwavelength-sized silver nanocubes are mapped with nanometric spatial resolution by means of electron energy-loss spectroscopy in a scanning transmission electron microscope. Three main features with different energies and spatial behavior (two peaked at the corners, one on the edges) are identified and related to previous measurements on ensemble or individual nanoparticles. The highly subwavelength mapping of the energy position and intensity of the excitations shows that the surface plasmon modes, localized at specific areas of the particles, for example, the corners or the edges, are modified by their size, the presence of a substrate, and the very local environment. Helped by discrete dipole approximation numerical simulations, we discuss how local modifications of the environment affect the global modes of the particles. In particular, we show both experimentally and theoretically that absorption resonances at different corners of the same nanocube are largely independent of each other in energy and intensity. Our findings provide a better understanding of the spatial coherence of the surface plasmons in nanoparticles but also give useful insights about their roles in the nanoparticle sensing properties.
authors.affiliation: Laboratoire de Physique des Solides, University Paris-Sud, CNRS, UMR 8502, F-91405 Orsay Cedex, France.
authors.forename: Stefano
authors.initials: S
authors.lastname: Mazzucco
authors.forename: Nicolas
authors.initials: N
authors.lastname: Geuquet
authors.forename: Jian
authors.initials: J
authors.lastname: Ye
authors.forename: Odile
authors.initials: O
authors.lastname: Stéphan
authors.forename: Willem
authors.initials: W
authors.lastname: Van Roy
authors.forename: Pol
authors.initials: P
authors.lastname: Van Dorpe
authors.forename: Luc
authors.initials: L
authors.lastname: Henrard
authors.forename: Mathieu
authors.initials: M
authors.lastname: Kociak
mesh_terms: D003198:Computer Simulation; D008027:Light; D008956:Models, Chemical; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D012542:Scattering, Radiation; D012834:Silver / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D012834:Silver