On the universal scaling behavior of the distance decay of plasmon coupling in metal nanoparticle pairs: A plasmon ruler equation
On the universal scaling behavior of the distance decay of plasmon coupling in metal nanoparticle pairs: A plasmon ruler equation
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DOI：
10.1021/nl071008a
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发表时间：
2007-07-01
期刊：
影响因子：
10.8
通讯作者：
El-Sayed, Mostafa A.
中科院分区：
文献类型：
--
作者：
Jain, Prashant K.;Huang, Wenyu;El-Sayed, Mostafa A.
利用微吸收光谱和电动力学模拟研究了光刻法制备的金（Au）纳米盘对中的局域表面等离子体共振（LSPR）。与以前的工作一致，我们发现，分数等离子体激元波长移动的偏振沿着粒子间轴衰减与粒子间的间隙几乎呈指数关系。此外，我们发现对于不同的纳米颗粒尺寸、形状、金属类型或介质介电常数，衰减长度大约为0.2单位的颗粒尺寸。近指数距离衰减和有趣的“普遍”标度行为的粒子间等离子体激元耦合可以定性地解释的基础上的偶极耦合模型是由于两个因素的相互作用：直接依赖的单粒子极化率上的粒子尺寸的立方幂和衰减的等离子体激元近场的倒数距离的立方幂。使用这种普遍的缩放行为，我们能够推导出“等离子体标尺方程”，该方程从观察到的等离子体带的分数位移估计生物系统中Au纳米球之间的粒子间分离。我们发现很好的协议的粒子间的分离估计使用这个方程的实验观察莱因哈德等人。
Localized surface plasmon resonances (LSPR) in lithographically fabricated gold (Au) nanodisc pairs are investigated using microabsorption spectroscopy and electrodynamic simulations. In agreement with previous work, we find that the fractional plasmon wavelength shift for polarization along the interparticle axis decays nearly exponentially with the interparticle gap. In addition, we find that the decay length is roughly about 0.2 in units of the particle size for different nanoparticle size, shape, metal type, or medium dielectric constant. The near-exponential distance decay and the interesting "universal" scaling behavior of interparticle plasmon coupling can be qualitatively explained on the basis of a dipolar-coupling model as being due to the interplay of two factors: the direct dependence of the single-particle polarizability on the cubic power of the particle dimension and the decay of the plasmonic near-field as the cubic power of the inverse distance. Using this universal scaling behavior, we are able to derive a "plasmon ruler equation" that estimates the interparticle separation between Au nanospheres in a biological system from the observed fractional shift of the plasmon band. We find good agreement of the interparticle separations estimated using this equation with the experimental observations of Reinhard et al.