Visualizing plasmon coupling in closely spaced chains of Ag nanoparticles by electron energy-loss spectroscopy.
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.
Song
Fengqi
F
National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P R China.
Wang
Tingyu
T
Wang
Xuefeng
X
Xu
Changhui
C
He
Longbing
L
Wan
Jianguo
J
Van Haesendonck
Christian
C
Ringer
Simon P
SP
Han
Min
M
Liu
Zongwen
Z
Wang
Guanghou
G
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*
D012834:Silver