Kim Na Yeon, Cao Shaohong, More Karren L, Lupini Andrew R, Miao Jianwei, Chi Miaofang
Department of Physics and Astronomy and California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA.
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Small. 2023 Sep;19(37):e2208162. doi: 10.1002/smll.202208162. Epub 2023 May 18.
With the recent development of high-acquisition-speed pixelated detectors, 4D scanning transmission electron microscopy (4D-STEM) is becoming routinely available in high-resolution electron microscopy. 4D-STEM acts as a "universal" method that provides local information on materials that is challenging to extract from bulk techniques. It extends conventional STEM imaging to include super-resolution techniques and to provide quantitative phase-based information, such as differential phase contrast, ptychography, or Bloch wave phase retrieval. However, an important missing factor is the chemical and bonding information provided by electron energy loss spectroscopy (EELS). 4D-STEM and EELS cannot currently be acquired simultaneously due to the overlapping geometry of the detectors. Here, the feasibility of modifying the detector geometry to overcome this challenge for bulk specimens is demonstrated, and the use of a partial or defective detector for ptycholgaphic structural imaging is explored. Results show that structural information beyond the diffraction-limit and chemical information from the material can be extracted together, resulting in simultaneous multi-modal measurements, adding the additional dimensions of spectral information to 4D datasets.
随着高采集速度像素化探测器的最新发展，4D扫描透射电子显微镜（4D-STEM）在高分辨率电子显微镜中已变得常规可用。4D-STEM作为一种“通用”方法，可提供有关材料的局部信息，而从整体技术中提取这些信息具有挑战性。它将传统的STEM成像扩展到包括超分辨率技术，并提供基于定量相位的信息，例如差分相衬、叠层成像或布洛赫波相位恢复。然而，一个重要的缺失因素是电子能量损失谱（EELS）提供的化学和键合信息。由于探测器的几何结构重叠，目前无法同时获取4D-STEM和EELS。在此，展示了修改探测器几何结构以克服大块样品这一挑战的可行性，并探索了使用部分或有缺陷的探测器进行叠层成像结构成像。结果表明，可以一起提取超出衍射极限的结构信息和来自材料的化学信息，从而实现同步多模态测量，为4D数据集增加光谱信息的额外维度。
