Department of Materials Engineering, Monash University, VIC 3800, Australia.
Proc Natl Acad Sci U S A. 2013 Aug 27;110(35):14144-9. doi: 10.1073/pnas.1307323110. Epub 2013 Aug 12.
A century has passed since Bragg solved the first atomic structure using diffraction. As with this first structure, all atomic structures to date have been deduced from the measurement of many diffracted intensities using iterative and statistical methods. We show that centrosymmetric atomic structures can be determined without the need to measure or even record a diffracted intensity. Instead, atomic structures can be determined directly and quickly from the observation of crystallographic phases in electron diffraction patterns. Furthermore, only a few phases are required to achieve high resolution. This represents a paradigm shift in structure determination methods, which we demonstrate with the moderately complex α-Al2O3. We show that the observation of just nine phases enables the location of all atoms with a resolution of better than 0.1 Å. This level of certainty previously required the measurement of thousands of diffracted intensities.
布拉格利用衍射技术解析出第一个原子结构至今已有一个世纪。与第一个结构一样，迄今为止所有原子结构都是通过迭代和统计方法测量多个衍射强度来推断的。我们证明，对于中心对称的原子结构，无需测量甚至无需记录衍射强度即可确定其结构。相反，可以直接从电子衍射图样中晶体学相位的观察来快速确定原子结构。此外，仅需几个相位即可实现高分辨率。这代表了结构确定方法的范式转变，我们用中等复杂的α-Al2O3 进行了验证。我们证明，只需观察九个相位就可以以优于 0.1Å 的分辨率确定所有原子的位置。这种确定性水平以前需要测量数千个衍射强度。
