arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2012.07012physics.opticscond-mat.mtrl-sci
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用电子对小分子成像中多次散射和菲涅耳衍射的相对作用,第II部分:微分全息层析术

Relative roles of multiple scattering and Fresnel diffraction in the imaging of small molecules using electrons, Part II: Differential Holographic Tomography

T. E. Gureyev, H. M. Quiney, A. Kozlov, D. M. Paganin, G. Schmalz, L. J. Allen

摘要:

有人认为,在原子分辨率透射电子显微镜(TEM)的稀疏弱散射结构,如小的生物分子,多电子散射通常只有很小的影响,而分子内的菲涅耳衍射可以是显着的,由于本质上浅的焦深。这些事实表明,这种结构的三维重建从散焦图像系列收集在多个旋转方向的分子可以有效地执行为每个原子分别,使用非相干第一玻恩近似。相应的重建方法,这里称为差分全息层析,理论上开发和计算证明了几个数值模型的生物分子。结果表明,该方法是能够准确重建的原子在分子中的位置从TEM数据收集在一个小数目的随机取向的分子,与一个或多个散焦图像每个方向。可能的应用低温电子显微镜和其他领域进行了简要讨论。

英文摘要:

It has been argued that in atomic-resolution transmission electron microscopy (TEM) of sparse weakly scattering structures, such as small biological molecules, multiple electron scattering usually has only a small effect, while the in-molecule Fresnel diffraction can be significant due to the intrinsically shallow depth of focus. These facts suggest that the three-dimensional reconstruction of such structures from defocus image series collected at multiple rotational orientations of a molecule can be effectively performed for each atom separately, using the incoherent first Born approximation. The corresponding reconstruction method, termed here Differential Holographic Tomography, is developed theoretically and demonstrated computationally on several numerical models of biological molecules. It is shown that the method is capable of accurate reconstruction of the locations of atoms in a molecule from TEM data collected at a small number of random orientations of the molecule, with one or more defocus images per orientation. Possible applications to cryogenic electron microscopy and other areas are briefly discussed.

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