Abstract
Quantitative atomic resolution annular dark field scanning transmission electron microscopy (ADF STEM) has become a powerful technique for nanoparticle atom-counting. However, a lot of nanoparticles provide a severe characterisation challenge because of their limited size and beam sensitivity. Therefore, quantitative ADF STEM may greatly benefit from statistical detection theory in order to optimise the instrumental microscope settings such that the incoming electron dose can be kept as low as possible whilst still retaining single-atom precision. The principles of detection theory are used to quantify the probability of error for atom-counting. This enables us to decide between different image performance measures and to optimise the experimental detector settings for atom-counting in ADF STEM in an objective manner. To demonstrate this, ADF STEM imaging of an industrial catalyst has been conducted using the near-optimal detector settings. For this experiment, we discussed the limits for atomcounting diagnosed by combining a thorough statistical method and detailed image simulations.
Highlights
Home Search Collections Journals About Contact us My IOPscienceQuantitative annular dark field scanning transmission electron microscopy for nanoparticle atom-counting: What are the limits?
The observed intensity in atomic resolution STEM images is highly sensitive to the number of projected atoms in each atomic column
Four images of the same Pt/Ir particle were recorded at different magnifications and electron doses under nearoptimal detector settings (i.e. 35-190 mrad) at the QuAntEM, a double corrected FEI Titan3 working at 300 kV with a 20.2 mrad semi-convergence angle
Summary
Quantitative annular dark field scanning transmission electron microscopy for nanoparticle atom-counting: What are the limits?. This content has been downloaded from IOPscience. Please scroll down to see the full text. Ser. 644 012034 (http://iopscience.iop.org/1742-6596/644/1/012034) View the table of contents for this issue, or go to the journal homepage for more. Download details: IP Address: 146.175.11.185 This content was downloaded on 30/11/2015 at 14:15 Please note that terms and conditions apply. Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium 2 Department of Materials, Uni versity of Oxford, 16 Parks Road, Oxford OX1 3PH, UK
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