Managing light polarization via plasmon-molecule interactions within an asymmetric metal nanoparticle trimer
Managing light polarization via plasmon-molecule interactions within an asymmetric metal nanoparticle trimer
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DOI：
10.1073/pnas.0808365105
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发表时间：
2008-10-28
影响因子：
11.1
通讯作者：
Haran, Gilad
中科院分区：
文献类型：
--
作者：
Shegai, Timur;Li, Zhipeng;Haran, Gilad
光与金属纳米粒子的相互作用导致了由表面等离子体激元激发介导的新现象。在这篇文章中，我们使用单分子来表征表面等离子体激元与光的相互作用，并表明这种相互作用可以强烈地调制发射光的偏振。能够实现这种偏振调制的最简单的纳米结构是不对称的银拉曼三聚体，其中单独的拉曼散射分子位于两个纳米颗粒之间的差距中。第三个粒子打破了双粒子结的偶极对称性，产生了依赖于波长的偏振模式。实际上，散射光变成椭圆偏振，并且其强度图案在第三粒子的存在下旋转。我们使用单分子的光谱观测，扫描电子显微镜成像和广义米氏理论计算的组合，以提供粒子对发射光的偏振的影响的全貌。此外，我们的理论分析使我们能够表明，所观察到的现象是非常敏感的三聚体颗粒的大小和它们的相对位置，这表明未来的手段，在纳米尺度上的光偏振的精确控制。
The interaction of light with metal nanoparticles leads to novel phenomena mediated by surface plasmon excitations. In this article we use single molecules to characterize the interaction of surface plasmons with light, and show that such interaction can strongly modulate the polarization of the emitted light. The simplest nanostructures that enable such polarization modulation are asymmetric silver nanocrystal trimers, where individual Raman scattering molecules are located in the gap between two of the nanoparticles. The third particle breaks the dipolar symmetry of the two-particle junction, generating a wavelength-dependent polarization pattern. Indeed, the scattered light becomes elliptically polarized and its intensity pattern is rotated in the presence of the third particle. We use a combination of spectroscopic observations on single molecules, scanning electron microscope imaging, and generalized Mie theory calculations to provide a full picture of the effect of particles on the polarization of the emitted light. Furthermore, our theoretical analysis allows us to show that the observed phenomenon is very sensitive to the size of the trimer particles and their relative position, suggesting future means for precise control of light polarization on the nanoscale.