Low-Loss Electric and Magnetic Field-Enhanced Spectroscopy with Subwavelength Silicon Dimers
Low-Loss Electric and Magnetic Field-Enhanced Spectroscopy with Subwavelength Silicon Dimers
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DOI：
10.1021/jp4027018
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发表时间：
2013-07-04
影响因子：
3.7
通讯作者：
Aizpurua, Javier
中科院分区：
文献类型：
--
作者：
Albella, Pablo;Ameen Poyli, M.;Aizpurua, Javier
介电纳米粒子具有中等高的折射率和非常低的吸收（如Si和Ge在可见-近红外（VIS-NIR）范围）显示出磁介电行为，产生有趣的远场相干效应，如方向性现象或场增强在粒子表面附近。在金属的情况下，两个或两个以上的电介质粒子的合奏可以构成开发基于表面场增强效应的新的光谱工具的基本元素。在这里，我们探索的基本单元构成的介电纳米粒子的二聚体的适度低损耗高折射率材料的电磁行为。负责的散射辐射和场增强的二聚体的光谱特征的相互作用，确定和研究通过分析偶极-偶极模型。位于二聚体间隙中的单个发射体（电偶极子或磁偶极子）的荧光也通过计算量子效率和辐射速率的淬灭/增强来探索。沿着该分析，与金属二聚体进行比较。这项研究开辟了新的可能性，执行场增强光谱和传感与纳米结构制成的合适的介电材料。
Dielectric nanoparticles with moderately high refractive index and very low absorption (like Si and Ge in the visible-near-infrared (VIS-NIR) range) show a magnetodielectric behavior that produces,interesting far-field coherent effects, like directionality phenomena or field enhancement in the proximity of the particle surface. As in the case of metals, ensembles of two or more dielectric particles can constitute basic elements for developing new spectroscopic tools based on surface field enhancement effects. Here we explore the electromagnetic behavior of the basic unit constituted by a dimer of dielectric nanoparticles made of moderately low-loss high refractive index material. The interactions responsible for the spectral features of the scattered radiation and field enhancement of the dimer are identified and studied through an analytical dipole-dipole model. The fluorescence of a single emitter (either electric or magnetic dipole) located in the dimer gap is also explored by calculating the quantum efficiencies and the quenching/enhancement of the radiation rates. Along this analysis, a comparison with metallic dimers is carried Out. This study opens new possibilities to perform field-enhanced spectroscopy and sensing with nanostructures made of suitable dielectric materials.