Abstract A novel dimeric arrangement consisting of two spherical nanocrescents with tips pointing at each other in nanometer proximities is proposed. Hybridization of the plasmonic modes in close proximities leads to a 48% enhancement in Purcell factor inside the gap compared to the single spherical nanocrescent. A nanometer resolved tomographic cathodoluminescence (CL) spectroscopy combined with radiative local density of optical states (LDOS) calculation have been utilized to investigate bright surface plasmon modes of the nanocrescent in three dimensions. In this work, the retarded full Maxwell equations are solved using the boundary element method (BEM) with the electron beam and point dipole sources. Then, tomographic reconstructions are produced from a set of 2D CL maps in different orientations via the simultaneous iterative reconstruction technique (SIRT). The procedure of achieving CL tomograms and its connection to radiative LDOS are, first, validated for well-established cylindrical nanocrescent and then applied to the spherical nanocrescent dimer. The new proposed plasmonic dimer with promising radiative optical properties obtained in three dimensions shows enormous potential to play the main role in applications such as in vivo biosensing based on plasmonic-enhanced fluorescence and also surface-enhanced Raman spectroscopy (SERS).

中文翻译：

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圆柱形和二聚体球形纳米新月体局部表面等离子体共振的 3D 断层成像

摘要 提出了一种由两个球形纳米新月体组成的新型二聚体排列，其尖端在纳米范围内相互指向。与单个球形纳米新月相比，近距离等离子体模式的杂交导致间隙内的珀塞尔因子增强了 48%。纳米分辨断层扫描阴极发光 (CL) 光谱结合光态辐射局部密度 (LDOS) 计算已被用于研究纳米新月体在三个维度上的明亮表面等离子体模式。在这项工作中，使用电子束和点偶极子源使用边界元法 (BEM) 求解延迟的全麦克斯韦方程。然后，断层扫描重建是通过同时迭代重建技术 (SIRT) 从一组不同方向的 2D CL 图产生的。实现 CL 断层扫描的过程及其与辐射 LDOS 的连接首先针对成熟的圆柱形纳米新月进行验证，然后应用于球形纳米新月二聚体。新提出的等离子体二聚体具有在三个维度上获得的有前景的辐射光学特性，显示出在基于等离子体增强荧光和表面增强拉曼光谱 (SERS) 的体内生物传感等应用中发挥主要作用的巨大潜力。