Size and shape of nanoclusters: single-shot imaging approach.
Bottom Line: A method of single-shot imaging via aberration-corrected scanning transmission electron microscopy equipped with high angle annular dark-field detector (STEM-HAADF) has been applied to size-selected gold model catalysts (Au(25) and Au(39) ) on hydroxyapatite.Through quantitative intensity analysis, the size, in terms of number of atoms as well as 3D shape of the clusters are obtained.
Affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.Show MeSH
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Mentions: To gain insight of the bonding strength between clusters and the HAP support, we plot in Figure4 the integrated HAADF intensity of each cluster as a function of its diameter, together with the relationship generated from the idealized spherical and hemispherical models (shown with solid and dashed lines). In the geometric models, the Wigner-Seitz radius of gold, rws = 0.165 nm, is used.10, 14 It is clear from Figure 4 that majority data points, though scattered, follow the trend of the hemispherical model, when the diameter is less than ∼2 nm. The result suggests that the clusters are flattened on the support, likely as a result of the strong interaction between the Au and PO43− moieties of HAP.15
Affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.