npj: 机器视觉——分辨出千胞胎孩子的绝技
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高分辨率扫描透射电子显微镜和扫描探针显微镜的最新技术能使研究人员对材料结构参数和功能特性进行测量，测量精度可达皮米（10-12 m）级，但却难以准确地识别（“读出”）不同原子/分子结构中的所有不同构件，难以对几百到几千个原子/分子组成的复杂图案进行分类。金表面的“buckybowl”分子（一种心环烯）结构纷繁复杂，其微观图像大致象一只碗，可以面朝上或朝下放置，有不同的旋转取向，不同分子排列起来犹如图案丰富的挂毯，也像一千个千胞胎孩子站在你面前，让你无法肉眼区分，甚至无法用现有计算方法进行分类。然而，来自美国橡树岭国家实验室的Sergei Kalinin（本刊学术编辑）、Maxim Ziatdinov和Artem Maksov改进了用于癌症检测和卫星成像的技术，开发出了一种“机器视觉”方法，能够自动识别和分类材料表面的数千个buckybowls分子，能够揭示其如何与邻居相互作用、构建出复杂阵列图案的细节，并有望用于分子存储器件的设计。该文近期发表于npj Computational Materials 3:31 (2017); doi:10.1038/s41524-017-0038-7。英文标题与摘要如下，点击阅读原文可以自由获取论文PDF。
Learning surface molecular structures via machine vision
Maxim Ziatdinov, Artem Maksov & Sergei V. Kalinin
Recent advances in high resolution scanning transmission electron and scanning probe microscopies have allowed researchers to perform measurements of materials structural parameters and functional properties in real space with apicometre precision. In many technologically relevant atomic and/or molecular systems, however, the information of interest is distributed spatially in anon-uniform manner and may have a complex multi-dimensional nature. One of the critical issues, therefore, lies in being able to accurately identify (‘read out’) all the individual building blocks in different atomic/molecular architectures, as well asmore complex patterns that these blocks may form, on a scale of hundreds and thousands of individual atomic/molecular units. Here we employ machine vision to read and recognize complex molecular assemblies on surfaces. We show how the obtained full decoding of the system allows us to directly construct a pair density function—a centerpiece in analysis of disorder-property relationship paradigm—as well as to analyze spatial correlations between multiple order parameters at the nanoscale, and elucidate reaction pathway involving molecular conformation changes. The method represents a significant shift in our way of analyzing atomic and/or molecular resolved microscopic images and can be applied to variety of other microscopic measurements of structural, electronic,and magnetic orders in different condensed matter systems.
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