Direct visualization of reversible dynamics in a Si6 cluster embedded in a graphene pore

• Published in: Nature communications Vol. 4; no. 1; p. 1650
• Main Authors: Lee, Jaekwang, Zhou, Wu, Pennycook, Stephen J., Idrobo, Juan-Carlos, Pantelides, Sokrates T.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 03.04.2013; Nature Publishing Group
• Subjects: 639/766/119; 639/766/36; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms2671

Clusters containing only a handful of atoms have been the subject of extensive theoretical and experimental studies, but their direct imaging has not been possible so far, with information about their structure provided mainly by theory. Here we report a direct atomically-resolved observation of a single Si 6 cluster trapped in a graphene nanopore. Furthermore, though electron-beam-induced irreversible atomic displacements have been reported before, here we report a sequence of images that show a reversible, oscillatory, conformational change: one of the Si atoms jumps back and forth between two different positions. Density-functional calculations show that the embedded cluster is exploring metastable configurations under the influence of the beam, providing direct information on the atomic-scale energy landscape. The capture of a Si cluster in a graphene nanopore suggests the possibility of patterning nanopores and assembling atomic clusters with a potential for applications. Studying the structural dynamics of clusters of just a handful of atoms is challenging. But by imaging a cluster of six silicon atoms trapped in a pore of a sheet of graphene with an electron microscope, Lee et al . observe the reversible switching of the cluster between different metastable structural states.