Controlling atomic structure and dynamics with single-atom precision is the ultimate goal in nanoscience and nanotechnology. Despite great successes being achieved by scanning tunneling microscopy (STM) over the past a few decades, fundamental limitations, such as ultralow temperature, and low throughput, significantly hinder the fabrication of a large array of atomically defined structures by STM. The advent of aberration correction in scanning transmission electron microscopy (STEM) revolutionized the field of nanomaterials characterization pushing the detection limit down to single-atom sensitivity. The sub-angstrom focused electron beam (e-beam) of STEM is capable of interacting with an individual atom, thereby it is the ideal platform to direct and control matter with a single atom or a small cluster. In this article, we discuss the transfer of energy and momentum from the incident e-beam to atoms and their subsequent potential dynamics under different e-beam conditions in 2D materials, particularly transition metal dichalcogenides (TMDs). Next, we systematically discuss the e-beam triggered structural evolutions of atomic defects, line defects, grain boundaries, and stacking faults in a few representative 2D materials. Their formation mechanisms, kinetic paths, and practical applications are comprehensively discussed. We show that desired structural evolution or atom-by-atom assembly can be precisely manipulated by e-beam irradiation which could introduce intriguing functionalities to 2D materials. In particular, we highlight the recent progress on controlling single Si atom migration in real-time on monolayer graphene along an extended path with high throughput in automated STEM. These results unprecedentedly demonstrate that single-atom dynamics can be realized by an atomically focused e-beam. With the burgeoning of artificial intelligence and big data, we can expect that fully automated microscopes with real-time data analysis and feedback could readily design and fabricate large scale nanostructures with unique functionalities in the near future.

中文翻译：

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电子束触发二维材料中的单原子动力学

以单原子精度控制原子结构和动力学是纳米科学和纳米技术的最终目标。尽管在过去的几十年中，扫描隧道显微镜 (STM) 取得了巨大的成功，但诸如超低温和低通量等基本限制极大地阻碍了 STM 制造大量原子定义的结构。扫描透射电子显微镜 (STEM) 中像差校正的出现彻底改变了纳米材料表征领域，将检测极限推低至单原子灵敏度。STEM的亚埃聚焦电子束（e-beam）能够与单个原子相互作用，因此它是用单个原子或小簇引导和控制物质的理想平台。在这篇文章中，我们讨论了能量和动量从入射电子束到原子的转移，以及它们在二维材料中不同电子束条件下的潜在动力学，特别是过渡金属二硫属化物 (TMDs)。接下来，我们系统地讨论了一些代表性二维材料中原子缺陷、线缺陷、晶界和堆垛层错的电子束触发结构演变。对其形成机制、动力学路径和实际应用进行了全面讨论。我们表明，可以通过电子束辐照精确地操纵所需的结构演化或逐个原子的组装，这可以为二维材料引入有趣的功能。特别是，我们重点介绍了在单层石墨烯上实时控制单硅原子迁移的最新进展，该进展沿扩展路径在自动化 STEM 中具有高吞吐量。这些结果前所未有地表明，单原子动力学可以通过原子聚焦的电子束来实现。随着人工智能和大数据的蓬勃发展，我们可以期待具有实时数据分析和反馈功能的全自动显微镜可以在不久的将来轻松设计和制造具有独特功能的大规模纳米结构。