title: Visualizing plasmon coupling in closely spaced chains of Ag nanoparticles by electron energy-loss spectroscopy.
abstract: Anisotropic plasmon coupling in closely spaced chains of Ag nanoparticles is visualized using electron energy-loss spectroscopy in a scanning transmission electron microscope. For dimers as the simplest chain, mapping the plasmon excitations with nanometer spatial resolution and an energy resolution of 0.27 eV intuitively identifies two coupling plasmons. The in-phase mode redshifts from the ultraviolet region as the interparticle spacing is reduced, reaching the visible range at 2.7 eV. Calculations based on the discrete-dipole approximation confirm its optical activeness, where the longitudinal direction is constructed as the path for light transportation. Two coupling paths are then observed in an inflexed four-particle chain.
authors.affiliation: National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P R China.
authors.forename: Fengqi
authors.initials: F
authors.lastname: Song
authors.forename: Tingyu
authors.initials: T
authors.lastname: Wang
authors.forename: Xuefeng
authors.initials: X
authors.lastname: Wang
authors.forename: Changhui
authors.initials: C
authors.lastname: Xu
authors.forename: Longbing
authors.initials: L
authors.lastname: He
authors.forename: Jianguo
authors.initials: J
authors.lastname: Wan
authors.forename: Christian
authors.initials: C
authors.lastname: Van Haesendonck
authors.forename: Simon P
authors.initials: SP
authors.lastname: Ringer
authors.forename: Min
authors.initials: M
authors.lastname: Han
authors.forename: Zongwen
authors.initials: Z
authors.lastname: Liu
authors.forename: Guanghou
authors.initials: G
authors.lastname: Wang
mesh_terms: D019281:Dimerization; D004583:Electrons; D004601:Elementary Particles; D053768:Metal Nanoparticles / Q000737:chemistry*; D008956:Models, Chemical; D055620:Optical Phenomena; D012834:Silver / Q000737:chemistry*; D046590:Spectroscopy, Electron Energy-Loss / Q000379:methods*
chemical_list: D012834:Silver