Plasmonics of 3-D nanoshell dimers using multipole expansion and finite element method.
Plasmonics of 3-D nanoshell dimers using multipole expansion and finite element method.
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DOI：
10.1021/nn900664j
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发表时间：
2009-09-22
期刊：
影响因子：
17.1
通讯作者：
Vo-Dinh T
中科院分区：
文献类型：
--
作者：
Khoury CG;Norton SJ;Vo-Dinh T
采用多极展开法（ME）和COMSOL有限元法（FEM），分别对金和银三维纳米壳二聚体的差距诱导等离子体激元场的空间和光谱响应进行了理论和模拟研究。在二聚体间隙的电场进行了评价和比较作为壳厚度，颗粒间距离和尺寸的函数。电场随着壳厚度的减小、颗粒间距离的减小和尺寸的增大而增大，两种方法之间的误差范围为1%至10%，这取决于这三个变量的具体组合。随着二聚体尺寸的增加，该误差增加数倍，因为准静态近似被打破。相对于ME，FEM对等离子体激元的半高宽和等离子体激元峰的红移有一致的高估，并且随着壳层厚度和颗粒间距离的减小而增加。电子表面散射引起的尺寸效应得到了解决，并且对于薄壳来说尤其突出，在薄壳中观察到了等离子体激元带的显着衰减、加宽和位移;尺寸效应还影响大的纳米壳二聚体，具体取决于它们的相对壳厚度，但程度较小。这项研究表明，COMSOL是一个很有前途的模拟环境，定量研究纳米电磁建模和设计的表面增强拉曼散射（Sers）基板。
The spatial and spectral responses of the plasmonic fields induced in the gap of 3-D Nanoshell Dimers of gold and silver are comprehensively investigated and compared via theory and simulation, using the Multipole Expansion (ME) and the Finite Element Method (FEM) in COMSOL, respectively. The E-field in the dimer gap was evaluated and compared as a function of shell thickness, inter-particle distance, and size. The E-field increased with decreasing shell thickness, decreasing interparticle distance, and increasing size, with the error between the two methods ranging from 1 to 10%, depending on the specific combination of these three variables. This error increases several fold with increasing dimer size, as the quasi-static approximation breaks down. A consistent overestimation of the plasmon’s FWHM and red-shifting of the plasmon peak occurs with FEM, relative to ME, and it increases with decreasing shell thickness and inter-particle distance. The size-effect that arises from surface scattering of electrons is addressed and shown to be especially prominent for thin shells, for which significant damping, broadening and shifting of the plasmon band is observed; the size-effect also affects large nanoshell dimers, depending on their relative shell thickness, but to a lesser extent. This study demonstrates that COMSOL is a promising simulation environment to quantitatively investigate nanoscale electromagnetics for the modeling and designing of Surface Enhanced Raman Scattering (SERS) substrates.
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影响因子：
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