HAADF‐STEM image analysis for size‐selected platinum nanoclusters

Abstract

SummaryIn this study, size‐selected platinum (Pt) nanoclusters were imaged with aberration‐corrected scanning transmission electron microscopy in high‐angle annular dark field (HAADF) mode. For image analysis, a relatively simple macro program was developed by making the use of existing ImageJ plug‐ins. The macro allows effectively for assessing criterions chosen for intensity threshold and filter blurring factors. It can extract the integrated HAADF intensity, peak intensity and projected area of the clusters. Here, the effects of magnification and objective lens defocus on nanocluster measurement were investigated. It was found that the integrated HAADF intensity of Pt clusters is a more robust sample descriptor than the peak intensity and the projected area. The macro program developed is freely available.Lay DescriptionMeasuring precisely the size of nanoclusters plays an important role in the investigation of nanocluster‐based material systems. Aberration‐corrected scanning transmission electron microscopy (STEM) is one of the most powerful tools to extract the size of clusters directly from their images. In this study, we developed a macro program based on existing ImageJ plug‐ins, allowing easy‐assessment of criterions chosen for image intensity threshold and filter blurring factors. It can be used to extract the integrated intensity, peak intensity, and projected area of the clusters for size determination. Using the program, we investigated the effects of magnification and objective lens defocus on measurements performed on size‐selected platinum (Pt) nanoclusters, and found that the integrated intensity of Pt clusters is a more robust sample descriptor than the peak intensity and the projected area. The macro developed allows a rapid assessment of factors affecting the accuracy with which size information can be obtained from clusters.

Pt147 Nanoclusters Soft-Landed on WS2 Nanosheets for Catalysis and Energy Harvesting

“…For these reasons, integrated HAADF intensity is a more robust descriptor for small metal clusters. 46 High-resolution imaging of the Pt 147 clusters on WS 2 as shown in Figure S10 reveals predominantly noncrystalline structures, with structural features indicative of partial icosahedral motifs, which is consistent with the findings of Lambie et al 27 Larger sintered clusters, identified through their integrated HAADF intensity, are observed to have crystalline FCC structures.…”

“…The projected area distribution of the Pt 147 clusters is broader (i.e., width divided by mean value) than the integrated intensity distribution due to various reasons, including thresholding uncertainties and differing Pt 147 arrangements and structures on the WS 2 surface. For these reasons, integrated HAADF intensity is a more robust descriptor for small metal clusters . High-resolution imaging of the Pt 147 clusters on WS 2 as shown in Figure S10 reveals predominantly noncrystalline structures, with structural features indicative of partial icosahedral motifs, which is consistent with the findings of Lambie et al Larger sintered clusters, identified through their integrated HAADF intensity, are observed to have crystalline FCC structures.…”

“…This is consistent with real-time HAADF-STEM data of suspended WS 2 -Pt 147 under the electron beam, which will be discussed later. On the other hand, the A 1g peak of suspended WS 2 -Pt 147 also shows a 2 cm −1 red shift, which may be a consequence of charge transfer from Pt 147 clusters to WS 2 as A 1g is reportedly sensitive to the doping and substrate effect 46 and shows a redshift when there is an increase in electron concentration. 47 Thus, the collective Raman features not only confirm the presence of Pt 147 clusters but also show a charge transfer effect from Pt clusters to WS 2 layers.…”

Extension of Rietveld Refinement for Benchtop Powder XRD Analysis of Ultrasmall Supported Nanoparticles

“…It is noted that because not all of the Pt nanoparticles are fully in focus in the images, these presented particle sizes (based on the projected area in the images) are an upper estimate of the particle size. The actual sizes of the measured particles in the electron beam are likely somewhat smaller (Xia et al 29 ). XRD.…”