Fengqi Song, Tingyu Wang, Xuefeng Wang, Changhui Xu, Longbing He, Jianguo Wan, Chris Van Haesendonck, Simon P. Ringer, Min Han, Zongwen Liu, Guanghou Wang
Anisotropic plasmon coupling in closely-spaced chains of Ag nanoparticles was
visualized using the electron energy loss spectroscopy in a scanning
transmission electron microscope. For dimers as the simplest chain, mapping the
plasmon excitations with nanometers' spatial resolution and 0.27 eV energy
resolution intuitively identified two coupling plasmons. The in-phase mode
redshifted from the ultraviolet region as the inter-particle spacing was
reduced, reaching the visible range at 2.7 eV. Calculations based on the
discrete dipole approximation confirmed its optical activeness, where the
longitudinal direction was constructed as the path for light transportation.
Two coupling paths were then observed in an inflexed 4-particle chain.
View original:
http://arxiv.org/abs/1202.2610
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