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Instruments / Technical Area	Publication Details	Published
E02-JEM ARM 300CF	Characterisation of the morphology of surface-assembled Au nanoclusters on amorphous carbon Malcolm Dearg , Sean Lethbridge , James Mccormack , Richard E. Palmer , Thomas Slater Nanoscale DOI: 10.1039/D4NR00978A Diamond Proposal Number(s): [28449] Open Access Show Abstract ▼ Abstract: In this study, aberration-corrected scanning transmission electron microscopy is employed to investigate the morphology of Au clusters formed from the aggregation of single atoms sputtered onto an amorphous carbon surface. The morphologies of surface-assembled clusters of N > 100 atoms are referenced against the morphologies of size-selected clusters determined from previously published results. We observe that surface-assembled clusters (at the conditions employed here) are approximately spherical in shape. The structural isomers of the imaged clusters have also been identified, and the distribution of structural types is broadly in agreement with those from size-selected cluster deposition sources. For clusters of approximately 147 atoms, we find a preference for icosahedra over decahedra and cuboctahedra, but at this size there is a high proportion of unidentified/amorphous structures. At around 309 atoms, we find a preference for decahedra over icosahedra and cuboctahedra, but over half the structures remain unidentifiable/amorphous. For sizes above 561 atoms we are able to identify most of the structures, and find decahedra are still the most favoured, although in competition with single-crystal fcc morphologies. The similarity in structure between surface-assembled and size-selected clusters from a cluster source provides evidence of the relevance of size-selected cluster studies to clusters synthesised by other, industrially relevant, methodologies.	May 2024
E02-JEM ARM 300CF	Stabilization of 2D raft structures of Au nanoclusters with up to 60 atoms by a carbon support Sean Lethbridge , Theodoros Pavloudis , James Mccormack , Thomas Slater , Joseph Kioseoglou , Richard E. Palmer Small Science 1190 DOI: 10.1002/smsc.202400093 Diamond Proposal Number(s): [28449] Open Access Show Abstract ▼ Abstract: Herein, the stabilization of 2D single-atom high gold rafts containing up to ≈60 Au atoms on amorphous carbon, fabricated by sputtering of atoms and imaged by aberration-corrected scanning transmission electron microscopy, is demonstrated. These rafts deviate from the established cluster transition from 2D to 3D Au structural motifs in free clusters, which occurs in the region of 10–14 atoms. The experimental findings by performing explicit ab initio calculations of Aun (n = 3–147) clusters on graphene are supported and the role of cluster–surface interactions in the stabilization of the 2D single-atom high Au cluster rafts on graphene is revealed. The transition from equilibrium 2D–3D structures is delayed to n = 19, while metastable 2D single-atom high rafts compete with 3D structures up to about n = 60 atoms. The catalytic activity of supported nanoclusters depends strongly on their structure (and carbon-based supports are used for a number of reactions); therefore these results are relevant to the catalytic performance of nanocluster-based catalysts.	May 2024
E01-JEM ARM 200CF	Influence of air exposure on structural isomers of silver nanoparticles Jerome Vernieres , Nathalie Tarrat , Sean Lethbridge , Erica Watchorn-Rokutan , Thomas Slater , David Loffreda , Richard E. Palmer Communications Chemistry 6 DOI: 10.1038/s42004-023-00813-9 Diamond Proposal Number(s): [24588] Open Access Show Abstract ▼ Abstract: Up to date, the influence of ambient air exposure on the energetics and stability of silver clusters has rarely been investigated and compared to clusters in vacuum. Silver clusters up to 3000 atoms in size, on an amorphous carbon film, have been exposed to ambient air and investigated by atomic-resolution imaging in the aberration-corrected Scanning Transmission Electron Microscope. Ordered structures comprise more than half the population, the rest are amorphous. Here, we show that the most common ordered isomer structures is the icosahedron. These results contrast with the published behaviour of silver clusters protected from atmospheric exposure, where the predominant ordered isomer is face-centred cubic. We propose that the formation of surface oxide or sulphide species resulting from air exposure can account for this deviation in stable isomer. This interpretation is consistent with density functional theory calculations based on silver nanoclusters, in the size range 147-201 atoms, on which methanethiol molecules are adsorbed. An understanding of the effects of ambient exposure on the atomic structure and therefore functional properties of nanoparticles is highly relevant to their real-world performance and applications.	Jan 2023

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