Quantitative STEM normalisation : the importance of the electron flux
Annular dark-field (ADF) scanning transmission electron microscopy (STEM) has become widely used in quantitative studies based on the opportunity to directly compare experimental and simulated images. This comparison merely requires the experimental data to be normalised and expressed in units of fractional beam-current. However, inhomogeneities in the response of electron detectors can complicate this normalisation. The quantification procedure becomes both experiment and instrument specific, requiring new simulations for the particular response of each instrument's detector, and for every camera-length used. This not only impedes the comparison between different instruments and research groups, but can also be computationally very time consuming. Furthermore, not all image simulation methods allow for the inclusion of an inhomogeneous detector response. In this work, we propose an alternative method for normalising experimental data in order to compare these with simulations that consider a homogeneous detector response. To achieve this, we determine the electron flux distribution reaching the detector by means of a camera-length series or a so-called atomic column cross-section averaged convergent beam electron diffraction (XSACBED) pattern. The result is then used to determine the relative weighting of the detector response. Here we show that the results obtained by this new electron flux weighted (EFW) method are comparable to the currently used method, while considerably simplifying the needed simulation libraries. The proposed method also allows one to obtain a metric that describes the quality of the detector response in comparison with the ideal detector response.
Source (journal)
Ultramicroscopy. - Amsterdam
Amsterdam : 2015
159:1(2015), p. 46-58
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Project info
ESTEEM 2 - Enabling science and technology through European electron microscopy.
Exploring electron vortex beams (VORTEX).
Counting Atoms in Nanomaterials (COUNTATOMS).
Bringing light atoms to light: precise characterization of light-atom nanostructures using transmission electron microscopy.
Complex hetero-nanosystems: three-dimensional characterisation down to the atomic scale.
Revealing the source of emergent properties in complex oxides via direct imaging of charge/orbital/spin ordering.
Publication type
Publications with a UAntwerp address
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Web of Science
Creation 07.09.2015
Last edited 05.01.2018
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