The local surface plasmon resonance properties in systems consisting of silver nanosphere clusters are studied by Green’s function. The extinction, absorption, and scattering efficiencies band of two, three, and more silver nanospheres clusters are discussed in detail. The clusters show new types of the local surface plasmon resonances compared with single silver nanosphere. Our results suggest that the resonances depend strongly on individual particles’ characteristics such as their shapes, gap distances, directions and polarizations of incident light waves, and the number of clusters. The spectrum shows that equilateral triangle nanospheres has a good absorption peak, while the better red-shifted with three aligned nanospheres. In addition, the distributions of electric field intensity for three and four touched silver nanospheres are also investigated. The study is useful to broaden the application scope of Raman spectroscopy and nanooptics.

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Articles you may be interested inEngineering the plasmonic optical properties of cubic silver nanostructures based on Fano resonance Controlling the absorption spectrum within a thin amorphous silicon layer by using the size dependent plasmonic behaviour of silver nanoparticles J. Renewable Sustainable Energy 5, 031614 (2013); 10.1063/1.4809787Localized surface plasmon resonance of single silver nanoparticles studied by dark-field optical microscopy and spectroscopy J. Appl. Phys. 109, 034310 (2011); 10.1063/1.3544349Tunable near-infrared optical properties of three-layered metal nanoshells Near-field spectral characteristics, images, and optical parameters of silver nanoparticles are studied using Green's tensor. The Lippmann-Schwinger integral equation is discretized, and numerically solved with complex-conjugate gradient method-fast Fourier transform algorithm. Simulation models include placing nanoparticles in either an infinitely homogeneous medium or on a substrate, and illuminated either directly with plane waves or through a glass substrate under total internal reflection. Simulation results suggest that local plasmon resonance redshifts to longer wavelengths when dielectric constant of the surrounding medium increases or when a substrate is presented, but blueshifts to shorter wavelengths when the height of a nanoparticle increases. Due to the exponential attenuation behavior of evanescent waves, total intensity of electrical field attenuates quickly as the detection distance increases. Optical efficiencies, scattering efficiencies, absorption, and extinction efficiencies of Ag nanoparticles are also reported.

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