1] Department of Physics and Center of Integrated Nanomechanical Systems, University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA [2].
Nat Commun. 2013;4:2723. doi: 10.1038/ncomms3723.
The atomic structure of graphene edges is critical in determining the electrical, magnetic and chemical properties of truncated graphene structures, notably nanoribbons. Unfortunately, graphene edges are typically far from ideal and suffer from atomic-scale defects, structural distortion and unintended chemical functionalization, leading to unpredictable properties. Here we report that graphene edges fabricated by electron beam-initiated mechanical rupture or tearing in high vacuum are clean and largely atomically perfect, oriented in either the armchair or zigzag direction. We demonstrate, via aberration-corrected transmission electron microscopy, reversible and extended pentagon-heptagon (5-7) reconstruction at zigzag edges, and explore experimentally and theoretically the dynamics of the transitions between configuration states. Good theoretical-experimental agreement is found for the flipping rates between 5-7 and 6-6 zigzag edge states. Our study demonstrates that simple ripping is remarkably effective in producing atomically clean, ideal terminations, thus providing a valuable tool for realizing atomically tailored graphene and facilitating meaningful experimental study.
石墨烯边缘的原子结构对于决定截断石墨烯结构（特别是纳米带）的电学、磁学和化学性质至关重要。不幸的是，石墨烯边缘通常远非理想，存在原子尺度的缺陷、结构变形和意外的化学官能化，导致性质不可预测。在这里，我们报告了通过电子束引发的机械破裂或在高真空下撕裂制造的石墨烯边缘是清洁的，并且在很大程度上是原子完美的，取向为扶手椅或锯齿形。我们通过像差校正的透射电子显微镜证明了锯齿形边缘的可逆和扩展的五边形-七边形（5-7）重构，并实验和理论上探索了构型状态之间跃迁的动力学。在 5-7 和 6-6 锯齿形边缘状态之间的翻转速率上发现了良好的理论-实验一致性。我们的研究表明，简单的撕裂在产生原子清洁、理想的末端方面非常有效，从而为实现原子裁剪的石墨烯提供了有价值的工具，并促进了有意义的实验研究。
