document: Experimental studies of the dynamics of individual carbon atoms in graphene have been empowered by the recent progress in aberration-corrected transmission electron microscopy (AC-TEM) capable of sub-Ångstrom resolution. The examples include AC-TEM observations of the formation and annealing of Stone–Wales defects [1], edge reconstruction [2,3] and formation of a large hole in graphene sheet from a single vacancy defect [3]. The AC-TEM has been also exploited in visualization in real time of the process of self-assembly of graphene nanoribbons from molecular precursors [4,5] and formation of nanometre size hollow protrusion on the nanotube sidewall [6]. Based on AC-TEM observations of transformation of small finite graphene flake into fullerene, a new ‘top-down’ mechanism for the formation of fullerene under the electron beam radiation has been proposed [7]. The critical step in the proposed ‘top-down’ mechanism of the fullerene formation is creation of vacancies in small graphene flake as a result of knock-on damage by electrons of the imaging electron beam (e-beam). The subsequent formation of pentagons at the vacancy sites near the edge reduces the number of dangling bonds and triggers the curving process of graphene flake into a closed fullerene structure [7]. Thus, dynamic behaviour of vacancies near graphene edge plays a crucial role in explaining mechanisms of the e-beam assisted self-assembly and structural transformations in graphene-like structures.
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