Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
Department of Physics, University of Washington, Seattle, Washington 98195, United States.
Nano Lett. 2022 Sep 14;22(17):7158-7165. doi: 10.1021/acs.nanolett.2c02375. Epub 2022 Aug 29.
Free-electron-based measurements in scanning transmission electron microscopes (STEMs) reveal valuable information on the broadband spectral responses of nanoscale systems with deeply subdiffraction limited spatial resolution. Leveraging recent advances in manipulating the spatial phase profile of the transverse electron wavefront, we theoretically describe interactions between the electron probe and optically stimulated nanophotonic targets in which the probe gains energy while simultaneously transitioning between transverse states with distinct phase profiles. Exploiting the selection rules governing such transitions, we propose phase-shaped electron energy gain nanospectroscopy for probing the 3D polarization-resolved response field of an optically excited target with nanoscale spatial resolution. Considering ongoing instrumental developments, polarized generalizations of STEM electron energy loss and gain measurements hold the potential to become powerful tools for fundamental studies of quantum materials and their interaction with nearby nanostructures supporting localized surface plasmon or phonon polaritons as well as for noninvasive imaging and nanoscale 3D field tomography.
基于自由电子的扫描透射电子显微镜（STEM）测量技术具有远超衍射极限的空间分辨率，能够揭示纳米尺度系统在宽频光谱响应方面的有价值信息。利用在操控横向电子波前空间相位分布方面的最新进展，我们从理论上描述了电子探针与受光激发的纳米光子目标之间的相互作用，在这种相互作用中，探针在同时从具有不同相位分布的横向状态转变的过程中获得能量。利用控制这些转变的选择定则，我们提出了相位形电子能量增益纳米光谱学，用于探测具有纳米尺度空间分辨率的受光激发目标的 3D 偏振分辨响应场。考虑到正在进行的仪器开发，极化的 STEM 电子能量损失和增益测量的推广有可能成为研究量子材料及其与支持局域表面等离激元或声子极化激元的附近纳米结构相互作用的有力工具，同时也成为非侵入性成像和纳米尺度 3D 场层析成像的工具。
