Universal scaling of plasmon coupling in metal nanostructures: Extension from particle pairs to nanoshells
Universal scaling of plasmon coupling in metal nanostructures: Extension from particle pairs to nanoshells
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DOI：
10.1021/nl071496m
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发表时间：
2007-09-01
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.;El-Sayed, Mostafa A.
最近的研究表明，一对等离激元金属纳米颗粒之间的等离激元耦合强度随着颗粒尺寸缩放的颗粒间间隙的函数而下降，具有接近指数的衰减趋势，该趋势通常与纳米颗粒的尺寸、形状、金属类型或介质介电常数无关。在这封信中，我们将这种普遍的缩放行为扩展到介电核-金属壳纳米结构。通过使用二氧化硅核-金属纳米壳的扩展米氏理论模拟，我们表明，当将由固体纳米球共振波长缩放的纳米壳等离子体共振波长的偏移与由核半径缩放的壳厚度绘制时，具有不同尺寸（半径）的纳米壳表现出相同的近指数衰减。因此，纳米壳系统在物理上类似于粒子对系统，即纳米壳等离激元共振是由内壳表面（腔）和外壳表面（球体）等离激元在基本上由金属壳厚度给定的间隔距离上耦合产生的，这与Prodan、Halas和Nordlander的等离激元杂交模型一致。通过使用纳米壳系统中的通用缩放行为，我们提出了一种简单的表达式来预测给定尺寸的二氧化硅-金纳米壳的偶极等离子体共振。
It has been recently shown that the strength of plasmon coupling between a pair of plasmonic metal nanoparticles falls as a function of the interparticle gap scaled by the particle size with a near-exponential decay trend that is universally independent of nanoparticle size, shape, metal type, or medium dielectric constant. In this letter, we extend this universal scaling behavior to the dielectric core-metal shell nanostructure. By using extended Mie theory simulations of silica core-metal nanoshells, we show that when the shift of the nanoshell plasmon resonance wavelength scaled by the solid nanosphere resonance wavelength is plotted against the shell thickness scaled by the core radius, nanoshells with different dimensions (radii) exhibit the same near-exponential decay. Thus, the nanoshell system becomes physically analogous to the particle-pair system, i.e., the nanoshell plasmon resonance results from the coupling of the inner shell surface (cavity) and the outer shell surface (sphere) plasmons over a separation distance essentially given by the metal shell thickness, which is consistent with the plasmon hybridization model of Prodan, Halas, and Nordlander. By using the universal scaling behavior in the nanoshell system, we propose a simple expression for predicting the dipolar plasmon resonance of a silica-gold nanoshell of given dimensions.