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: Figure1a,b show two high-resolution images taken from samples of Au25 and Au29 supported on hydroxyapatite (HAP), respectively. Each cluster was analysed with the background subtracted with reference to its surrounding areas. The histograms of the integrated intensities for the samples Au25 and Au39 are shown in Figure2a,b, respectively. To determine the number of peaks (k) and the associated peak positions in each case, the Integrated Complete Likelihood (ICL) criterion was employed based on Gaussian distributions.12 The intensities larger than 120 × 104 for Au25 and 95 × 104 for Au39 were not included in the ICL calculation due to a small number of data points. The best fits were achieved when k = 8 for Au25 and k = 4 for Au39, corresponding the existence of 8 and 4 mixed Gaussian functions, respectively, as shown in Figure 2.
Affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham, B15 2TT, UK.