Direct Observation of Plasmon Band Formation and Delocalization in Quasi-Infinite Nanoparticle Chains
Direct Observation of Plasmon Band Formation and Delocalization in Quasi-Infinite Nanoparticle Chains
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DOI：
10.1021/acs.nanolett.9b01031
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发表时间：
2019-06-01
期刊：
影响因子：
10.8
通讯作者：
Fery, Andreas
中科院分区：
文献类型：
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作者：
Mayer, Martin;Potapov, Pavel L.;Fery, Andreas
金属纳米颗粒链以相对较低的介电损耗维持强约束表面等离子体。为了在波导等应用中利用这些特性，低无序长链的制造和对等离子体模式特性（如色散关系）的透彻理解是必不可少的。在这里，我们使用一个皱巴巴的模板进行定向自组装来组装金纳米颗粒链。通过这种可扩展的方法，可以制造从两个粒子（140纳米）到20个粒子（1500纳米）甚至更长的链。在边界元模拟、时域有限差分和简化偶极子耦合模型的支持下，电子能量损失谱详细揭示了等离子体波导模式从简并的单粒子模式演变的过程。与等离子体棒状结构显著不同的是，等离子体带受到激发能的限制，这使得光操作可以低于衍射极限。非简并表面等离激元模式在1500 nm的有效能量传播中显示出抑制的辐射损失。
Chains of metallic nanoparticles sustain strongly confined surface plasmons with relatively low dielectric losses. To exploit these properties in applications, such as waveguides, the fabrication of long chains of low disorder and a thorough understanding of the plasmon-mode properties, such as dispersion relations, are indispensable. Here, we use a wrinkled template for directed self-assembly to assemble chains of gold nanoparticles. With this up-scalable method, chain lengths from two particles (140 nm) to 20 particles (1500 nm) and beyond can be fabricated. Electron energy-loss spectroscopy supported by boundary element simulations, finite-difference time-domain, and a simplified dipole coupling model reveal the evolution of a band of plasmonic waveguide modes from degenerated single-particle modes in detail. In striking difference from plasmonic rod-like structures, the plasmon band is confined in excitation energy, which allows light manipulations below the diffraction limit. The non-degenerated surface plasmon modes show suppressed radiative losses for efficient energy propagation over a distance of 1500 nm.