Plasmon-enhanced luminescence near noble-metal nanospheres: Comparison of exact theory and an improved Gersten and Nitzan model
Plasmon-enhanced luminescence near noble-metal nanospheres: Comparison of exact theory and an improved Gersten and Nitzan model
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DOI：
10.1103/physrevb.76.115123
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发表时间：
2007-09-01
影响因子：
3.7
通讯作者：
Polman, A.
中科院分区：
文献类型：
--
作者：
Mertens, H.;Koenderink, A. F.;Polman, A.
基于精确电动力学理论，我们对靠近贵金属纳米球的光发射器的辐射和非辐射衰减率的变化进行了理论研究。我们发现，根据材料性质的不同，与共振耦合到等离子体模式相关的发光量子效率增强的最佳纳米球直径在30-110 nm范围内。发现最佳直径是在(1)发射器-等离子体耦合（对小球体最有效）和(2)等离子体离耦成辐射（对大球体最有效）之间的权衡。此外，我们证明了著名的Gersten和Nitzan模型并没有描述有限最优直径的存在，除非将模型扩展为辐射阻尼的修正因子。通过这种修正和动态去极化的修正，数学上更简单的Gersten和Nitzan模型提供了与偶极等离子体模式耦合相关的衰减率修正的相当精确的近似。我们预计，我们在本文中验证的Gersten和Nitzan模型将允许对形状各向异性对等离子体增强发光的影响进行分析研究。
We present a theoretical study of the modifications of the radiative and nonradiative decay rates of an optical emitter in close proximity to a noble-metal nanosphere, based on exact electrodynamical theory. We show that the optimal nanosphere diameter for luminescence quantum efficiency enhancement associated with resonant coupling to plasmon modes is in the range of 30-110 nm, depending on the material properties. The optimal diameter is found to be a trade-off between (1) emitter-plasmon coupling, which is most effective for small spheres, and (2) the outcoupling of plasmons into radiation, which is most efficient for large spheres. In addition, we show that the well-known Gersten and Nitzan model does not describe the existence of a finite optimal diameter unless the model is extended with the correction factor for radiation damping. With this correction and a correction for dynamic depolarization, the mathematically simpler Gersten and Nitzan model provides a reasonably accurate approximation of the decay rate modifications associated with coupling to the dipole plasmon mode. We anticipate that the Gersten and Nitzan model in the form that we validate in this paper for spheres will allow the analytical investigation of the influence of shape anisotropy on plasmon-enhanced luminescence.