In-situ aberration-corrected transmission electron microscopy combined with density functional theory (DFT) calculations are employed to elucidate the electron beam induced dynamics of surface dislocations on ~ 4 nm × 6 nm sized Au (100) terraces located on top of hillock shaped Au at room temperature and 77 K at video rate (20 frames/s). At room temperature, very small terraces (<4 × 5 atoms) sink into the lower terrace forming surface dislocations associated with a (5 × 1) surface reconstruction unit cell. This injection occurs provided that the number of atoms of the terrace fits the number of extra atoms required to form the surface dislocation. The surface dislocation consists of either 5 or 3 (Type I and Type II) hexagonally stacked atom rows. While the surface dislocations tend to reside near terrace edges, in ~ 20% of the video frames, the surface dislocation resides near the center of the terrace. The occurrence of Type I or Type II structures depends on the terrace width. DFT calculations show that Type I surface dislocations are more stable than Type II, for dislocations that do not span the entire terrace width, in agreement with observations. Surface dislocations are observed to flip by 90¿during the experimental observations; the pathway and energy barrier (1.01 eV) for such flips is clarified through DFT calculations. At 77 K, no injections are observed, but surface dislocations do rarely form from an unreconstructed surface. In addition to dislocation flipping, multiple, dynamic dislocation configurations were observed in conjunction with terrace growth along the dislocation direction.@en

In order to harvest the many promising properties of graphene in (electronic) applications, a technique is required to cut, shape, or sculpt the material on the nanoscale without inducing damage to its atomic structure, as this drastically influences the electronic properties of the nanostructure. Here, we reveal a temperature-dependent self-repair mechanism that allows near-damage-free atomic-scale sculpting of graphene using a focused electron beam. We demonstrate that by sculpting at temperatures above 600 °C, an intrinsic self-repair mechanism keeps the graphene in a single-crystalline state during cutting, even though the electron beam induces considerable damage. Self-repair is mediated by mobile carbon ad-atoms that constantly repair the defects caused by the electron beam. Our technique allows reproducible fabrication and simultaneous imaging of single-crystalline free-standing nanoribbons, nanotubes, nanopores, and single carbon chains.@en