Sub-ångström resolution of atomistic structures below 0.8 Å
Sub-ångström resolution of atomistic structures below 0.8 Å
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原子结构的亚原子分辨率低于 0.8 Å
DOI：
10.1080/13642810108223123
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
A. Thust
中科院分区：
文献类型：
--
作者：
M. O'Keefe;E. C. Nelson;Y. C. Wang;A. Thust
摘要 随着分辨率的提高，缺陷的微观表征变得更加容易。通过改善时间相干性（色差）和补偿空间不相干性，我们将高分辨率透射电子显微镜的极限扩展到亚埃级，从而实现了美国能源部国家电子显微镜中心 1 Å 显微镜 (OÅM) 项目的目标。 OÅM 将焦距系列图像处理软件与配备高度相干场发射电子枪的改进型 300 keV 电子显微镜相结合。通过在“α-null”欠焦值下操作以尽量减少空间不相干性的影响，并通过降低 OÅM 的电子枪提取电压以提高时间相干性，我们能够传输低于 0.8 Å 的信息。在 OÅM 中以 [112] 方向观察的硅测试样本中，我们能够“看到”仅相距 0.78 Å 的原子。此级别的亚埃级分辨率为材料研究人员提供了一种有效的工具，可以以前所未有的精度表征缺陷。
Abstract Microcharacterization of defects is greatly facilitated with improvement in resolution. By improving temporal coherence (chromatic aberration) and compensating spatial incoherence, we have achieved the goal of the 1 Å microscope (OÅM) project at the US Department of Energy's National Center for Electron Microscopy by extending the limits of high-resolution transmission electron microscopy to sub-ångström levels. The OÅM combines focal-series image-processing software with a modified 300 keV electron microscope equipped with a highly coherent field emission electron gun. By operating at an ‘α-null’ value of underfocus in order to minimize the effects of spatial incoherence, and by reducing the OÅM's electron-gun extraction voltage to improve temporal coherence, we are able to transfer information below 0.8 Å. In a test specimen of silicon viewed in the [112] orientation in the OÅM we are able to ‘see’ atoms separated by only 0.78 Å. Sub-ångström resolution at this level offers the materials researcher an effective tool for the characterization of defects with unprecedented precision.