Nano beam diffraction and precession in an energy filtered CS corrected transmission electron microscope
Nano beam diffraction and precession in an energy filtered CS corrected transmission electron microscope
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能量过滤 CS 校正透射电子显微镜中的纳米束衍射和进动
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
G. Pavia
中科院分区：
文献类型：
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作者：
G. Benner;H. Niebel;G. Pavia
纳米束衍射是收集直径小至1纳米的粒子结构信息的先决条件。我们在这里描述了一种新的射线路径，其中限制照明孔径在透射电子显微镜（TEM）的照明系统中被安排得更高，这样它就可以进一步被消放大。这导致了一个高度的灵活性有关的照明场和电子束的会聚角，而不需要重新调整枢轴点和重新聚焦的衍射透镜。我们发现，在真正的平行照明条件下，衍射场直径可低至20 nm，可以获得无伪影的衍射图案。讨论了物理衍射效应对纳米束衍射模式的限制。由于这些作用，照明场或衍射斑或两者都可能显示衍射条纹。对（进动）电子衍射斑图进行零能量损失滤波，增加了它们的对比度，使弱衍射斑可见。本文提出了一种在球面像差（CS）校正的TEM中获取（能量滤波进动）电子衍射斑图的方法，并给出了初步结果。（©2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim）
Nano beam diffraction is a prerequisite to collecting structural information from particles as small as 1 nm in diameter. We describe here a novel ray path, where the limiting illumination aperture is arranged higher up in the illumination system of a transmission electron microscope (TEM) so that it can be demagnified further. This results in a high flexibility concerning the illuminating field and electron beam convergence angle without any need for readjustments of pivot points and refocusing of the diffraction lens. We show that artifact‐free diffraction patterns can be obtained with diffraction fields down to 20 nm in diameter under genuine parallel illumination conditions. The limitations of the nano beam diffraction mode by physical diffraction effects are discussed. Either the illumination field or the diffraction spots or both may show diffraction fringes as a result of these effects. Zero energy loss filtering of (precession) electron diffraction spot patterns increases their contrast and makes weak diffraction spots visible. A method to acquire (energy filtered precession) electron diffraction spot pattern in a spherical aberration (CS) corrected TEM has been developed and first results are presented. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)