Continuous Wave Resonant Photon Stimulated Electron Energy-Gain and Electron Energy-Loss Spectroscopy of Individual Plasmonic Nanoparticles
Continuous Wave Resonant Photon Stimulated Electron Energy-Gain and Electron Energy-Loss Spectroscopy of Individual Plasmonic Nanoparticles
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DOI：
10.1021/acsphotonics.9b00830
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发表时间：
2019-10-01
期刊：
影响因子：
7
通讯作者：
Rack, Philip D.
中科院分区：
文献类型：
--
作者：
Liu, Chenze;Wu, Yueying;Rack, Philip D.
纳米结构材料中表面等离子体共振的独特光学特性引起了人们的广泛关注，广泛影响着从传感、光电子学到量子计算等基础研究和应用技术。透射电子显微镜中的电子能量损失光谱（EELS）以纳米级空间分辨率揭示了有关这些材料的完整等离子体光谱的有价值的信息。在这里，我们报告了一种新方法，通过连续波激光和连续电流、单色电子探针的同时照射，实验性地获取单个等离子体纳米颗粒的光子受激电子能量增益和受激电子能量损失响应。受激增益和受激损耗概率是相等的，并且在 0.5 x 10(8) 至 4 x 10(8) W/m(2) 的低辐照度范围内线性增加，超过该范围，过度加热会降低观测到的概率；重要的是，在我们的低辐照度范围内，光子能量必须与等离激元能量共振进行调整，才能出现受激增益和损耗峰值。基于费米黄金法则的理论模型阐明了等离激元如何在受激电子能量损失和增益事件中在电子探针和辐射场之间共振和相干地传递能量量子，反之亦然。这项研究开辟了一种全新的方法来探索激发态等离子共振的量子物理学，该方法不依赖于高强度激光脉冲或对 EELS 探测器的任何修改。
The unique optical properties of surface plasmon resonances in nanostructured materials have attracted considerable attention, broadly impacting both fundamental research and applied technologies ranging from sensing and optoelectronics to quantum computing. Electron energy-loss spectroscopy (EELS) in the transmission electron microscope has revealed valuable information about the full plasmonic spectrum of these materials with nanoscale spatial resolution. Here we report a novel approach for experimentally accessing the photon-stimulated electron energy-gain and stimulated electron energy-loss responses of individual plasmonic nanoparticles via the simultaneous irradiation of a continuous wave laser and continuous current, monochromated electron probe. Stimulated gain and loss probabilities are equivalent and increase linearly in the low-irradiance range of 0.5 x 10(8) to 4 x 10(8) W/m(2), above which excessive heating reduces the observed probabilities; importantly in our low-irradiance regime, the photon energy must be tuned in resonance with the plasmon energy for the stimulated gain and loss peaks to emerge. Theoretical modeling based on Fermi's golden rule elucidates how the plasmon resonantly and coherently shuttles energy quanta between the electron probe and the radiation field and vice versa in stimulated electron energy-loss and -gain events. This study opens a fundamentally new approach to explore the quantum physics of excited-state plasmon resonances that does not rely on high-intensity laser pulses or any modification to the EELS detector.