阴极荧光在表面等离激元研究领域的应用

表面等离激元以其独特的光学性质广泛应用于纳米尺度的局域电磁场增强、超高分辨成像及微弱光电探测.阴极荧光是电子与物质相互作用而产生的光学响应,利用电子束激发金属纳米结构能够实现局域等离激元共振,并在亚波长尺度实现对共振模式的调控,具有超高空间分辨的成像特点.阴极荧光探测通常结合扫描电子显微镜或透射电子显微镜而实现,目前己被应用于表面等离激元的探测及共振模式的分析.本文从阴极荧光物理机理出发,综述了单一金属纳米结构和金属耦合结构的等离激元共振模式阴极荧光研究进展,并总结了阴极荧光与角分辨、时间分辨以及电子能量损失谱等关键技术相结合的应用,进一步分析了其面临的关键问题,最后展望了阴极荧光等离激元研究方向.

Research progress of plasmonic cathodoluminesecence characterization

Surface plasmons as the collective electrons oscillation at the interface of metal and dielectric materials, have induced tremendous applications for the nanoscale light focusing, waveguiding, coupling, and photodetection. As the development of the modern technology, cathodoluminescence (CL) has been successfully applied to describe the plasmon resonance within the nanoscale. Usually, the CL detection system is combined with a high resolution scanning electron microscope (SEM). The fabricated plasmonic nanostructure is directly excited by the electron beam, and detected by an ultra-sensitive spectrometer and photodetector. Under the high energy electron stimulation, all of the plasmon resonances of the metallic nanostructure can be excited. Because of the high spatial resolution of the SEM, the detected CL can be used to analyze the details of plasmon resonance modes. In this review, we first briefly introduced the physical mechanism for the CL generation, and then discussed the CL emission of single plasmonic nanostructures such as different nanowires, nanoantennas, nanodisks and nanocavities, where the CL only describes the individual plasmon resonance modes. Second, the plasmon coupling behavior for the ensemble measurement was compared and analyzed for the CL detection. Finally, the CL detection with other advanced technologies were concluded. We believe with the development of the nanophotonics community, CL detection as a unique technique with ultra-high energy and spatial resolution has potential applications for the future plasmonic structure design and characterization.