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Exploring the atomic structure of 1.8 nm monolayer-protected gold clusters with aberration-corrected STEM

Jian Liu, Nan Jian, Isabel Ornelas, Alexander J. Pattison, Tanja Lahtinen, Kirsi Salorinne, Hannu Häkkinen, Richard Palmer Orcid Logo

Ultramicroscopy, Volume: 176, Pages: 146 - 150

Swansea University Author: Richard Palmer Orcid Logo

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Abstract

Monolayer-protected (MP) Au clusters present attractive quantum systems with a range of potential applications e.g. in catalysis. Knowledge of the atomic structure is needed to obtain a full understanding of their intriguing physical and chemical properties. Here we employed aberration-corrected sca...

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Published in: Ultramicroscopy
ISSN: 0304-3991
Published: 2017
Online Access: Check full text

URI: https://cronfa.swan.ac.uk/Record/cronfa49225
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Abstract: Monolayer-protected (MP) Au clusters present attractive quantum systems with a range of potential applications e.g. in catalysis. Knowledge of the atomic structure is needed to obtain a full understanding of their intriguing physical and chemical properties. Here we employed aberration-corrected scanning transmission electron microscopy (ac-STEM), combined with multislice simulations, to make a round-robin investigation of the atomic structure of chemically synthesised clusters with nominal composition Au144(SCH2CH2Ph)60 provided by two different research groups. The MP Au clusters were “weighed” by the atom counting method, based on their integrated intensities in the high angle annular dark field (HAADF) regime and calibrated exponent of the Z dependence. For atomic structure analysis, we compared experimental images of hundreds of clusters, with atomic resolution, against a variety of structural models. Across the size range 123–151 atoms, only 3% of clusters matched the theoretically predicted Au144(SR)60 structure, while a large proportion of the clusters were amorphous (i.e. did not match any model structure). However, a distinct ring-dot feature, characteristic of local icosahedral symmetry, was observed in about 20% of the clusters.
Keywords: Monolayer-protected gold clusters, Aberration-corrected STEM, Au144(SR)60, Atom counting method, Atomic structure
College: College of Engineering
Start Page: 146
End Page: 150