“Quantitative atomic resolution mapping using high-angle annular dark field scanning transmission electron microscopy”. Van Aert S, Verbeeck J, Erni R, Bals S, Luysberg M, van Dyck D, Van Tendeloo G, Ultramicroscopy 109, 1236 (2009). http://doi.org/10.1016/j.ultramic.2009.05.010
Abstract: A model-based method is proposed to relatively quantify the chemical composition of atomic columns using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. The method is based on a quantification of the total intensity of the scattered electrons for the individual atomic columns using statistical parameter estimation theory. In order to apply this theory, a model is required describing the image contrast of the HAADF STEM images. Therefore, a simple, effective incoherent model has been assumed which takes the probe intensity profile into account. The scattered intensities can then be estimated by fitting this model to an experimental HAADF STEM image. These estimates are used as a performance measure to distinguish between different atomic column types and to identify the nature of unknown columns with good accuracy and precision using statistical hypothesis testing. The reliability of the method is supported by means of simulated HAADF STEM images as well as a combination of experimental images and electron energy-loss spectra. It is experimentally shown that statistically meaningful information on the composition of individual columns can be obtained even if the difference in averaged atomic number Z is only 3. Using this method, quantitative mapping at atomic resolution using HAADF STEM images only has become possible without the need of simultaneously recorded electron energy loss spectra.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 166
DOI: 10.1016/j.ultramic.2009.05.010
|
“Throughput maximization of particle radius measurements by balancing size and current of the electron probe”. van den Broek W, Van Aert S, Goos P, van Dyck D, Ultramicroscopy 111, 940 (2011). http://doi.org/10.1016/j.ultramic.2010.11.025
Abstract: In thispaperweinvestigatewhichprobesizemaximizesthethroughputwhenmeasuringtheradiusof nanoparticlesinhighangleannulardarkfieldscanningtransmissionelectronmicroscopy(HAADFSTEM). The sizeandthecorrespondingcurrentoftheelectronprobedeterminetheprecisionoftheestimateofa particlesradius.Maximizingthroughputmeansthatamaximumnumberofparticlesshouldbeimaged withinagiventimeframe,sothataprespecifiedprecisionisattained.WeshowthatBayesianstatistical experimentaldesignisaveryusefulapproachtodeterminetheoptimalprobesizeusingacertainamount of priorknowledgeaboutthesample.Thedependenceoftheoptimalprobesizeonthedetectorgeometry and thediameter,variabilityandatomicnumberoftheparticlesisinvestigated.Anexpressionforthe optimalprobesizeintheabsenceofanykindofpriorknowledgeaboutthespecimenisderivedaswell.
Keywords: A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 7
DOI: 10.1016/j.ultramic.2010.11.025
|
“MULTEM : a new multislice program to perform accurate and fast electron diffraction and imaging simulations using graphics processing units with CUDA”. Lobato I, Van Dyck D, Ultramicroscopy 156, 9 (2015). http://doi.org/10.1016/j.ultramic.2015.04.016
Abstract: The main features and the GPU implementation of the MULTEM program are presented and described. This new program performs accurate and fast multislice simulations by including higher order expansion of the multislice solution of the high energy Schrodinger equation, the correct subslicing of the three-dimensional potential and top-bottom surfaces. The program implements different kinds of simulation for CTEM, STEM, ED, PED, CBED, ADF-TEM and ABF-HC with proper treatment of the spatial and temporal incoherences. The multislice approach described here treats the specimen as amorphous material which allows a straightforward implementation of the frozen phonon approximation. The generalized transmission function for each slice is calculated when is needed and then discarded. This allows us to perform large simulations that can include millions of atoms and keep the computer memory requirements to a reasonable level. (C) 2015 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 32
DOI: 10.1016/j.ultramic.2015.04.016
|
“How precise can atoms of a nanocluster be located in 3D using a tilt series of scanning transmission electron microscopy images?”.Alania M, De Backer A, Lobato I, Krause FF, Van Dyck D, Rosenauer A, Van Aert S, Ultramicroscopy 181, 134 (2017). http://doi.org/10.1016/j.ultramic.2016.12.013
Abstract: In this paper, we investigate how precise atoms of a small nanocluster can ultimately be located in three dimensions (3D) from a tilt series of images acquired using annular dark field (ADF) scanning transmission electron microscopy (STEM). Therefore, we derive an expression for the statistical precision with which the 3D atomic position coordinates can be estimated in a quantitative analysis. Evaluating this statistical precision as a function of the microscope settings also allows us to derive the optimal experimental design. In this manner, the optimal angular tilt range, required electron dose, optimal detector angles, and number of projection images can be determined.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.843
Times cited: 3
DOI: 10.1016/j.ultramic.2016.12.013
|
“Dynamical diffraction of high-energy electrons investigated by focal series momentum-resolved scanning transmission electron microscopy at atomic resolution”. Robert Hl, Lobato I, Lyu Fj, Chen Q, Van Aert S, Van Dyck D, Müller-Caspary K, Ultramicroscopy 233, 113425 (2022). http://doi.org/10.1016/j.ultramic.2021.113425
Abstract: We report a study of scattering dynamics in crystals employing momentum-resolved scanning transmission
electron microscopy under varying illumination conditions. As we perform successive changes of the probe
focus, multiple real-space signals are obtained in dependence of the shape of the incident electron wave.
With support from extensive simulations, each signal is shown to be characterised by an optimum focus for
which the contrast is maximum and which differs among different signals. For instance, a systematic focus
mismatch is found between images formed by high-angle scattering, being sensitive to thickness and chemical
composition, and the first moment in diffraction space, being sensitive to electric fields. It follows that a single
recording at one specific probe focus is usually insufficient to characterise materials comprehensively. Most
importantly, we demonstrate in experiment and simulation that the second moment (
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.2
DOI: 10.1016/j.ultramic.2021.113425
|
“Enamels in stained glass windows: preparation, chemical composition, microstructure and causes of deterioration”. Schalm O, van der Linden V, Frederickx P, Luyten S, van der Snickt G, Caen J, Schryvers D, Janssens K, Cornelis E, van Dyck D, Schreiner M, Spectrochimica acta: part B : atomic spectroscopy 64, 812 (2009). http://doi.org/10.1016/j.sab.2009.06.005
Abstract: Stained glass windows incorporating dark blue and purple enamel paint layers are in some cases subject to severe degradation while others from the same period survived the ravages of time. A series of dark blue, greenblue and purple enamel glass paints from the same region (Northwestern Europe) and from the same period (16early 20th centuries) has been studied by means of a combination of microscopic X-ray fluorescence analysis, electron probe micro analysis and transmission electron microscopy with the aim of better understanding the causes of the degradation. The chemical composition of the enamels diverges from the average chemical composition of window glass. Some of the compositions appear to be unstable, for example those with a high concentration of K2O and a low content of CaO and PbO. In other cases, the deterioration of the paint layers was caused by the less than optimal vitrification of the enamel during the firing process. Recipes and chemical compositions indicate that glassmakers of the 1617th century had full control over the color of the enamel glass paints they made. They mainly used three types of coloring agents, based on Co (dark blue), Mn (purple) and Cu (light-blue or greenblue) as coloring elements. Bluepurple enamel paints were obtained by mixing two different coloring agents. The coloring agent for redpurple enamel, introduced during the 19th century, was colloidal gold embedded in grains of lead glass.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); AXES (Antwerp X-ray Analysis, Electrochemistry and Speciation); Vision lab
Impact Factor: 3.241
Times cited: 28
DOI: 10.1016/j.sab.2009.06.005
|
“Energy-filtered transmission electron microscopy: an overview”. Verbeeck J, van Dyck D, Van Tendeloo G, Spectrochimica acta: part B : atomic spectroscopy 59, 1529 (2004). http://doi.org/10.1016/j.sab.2004.03.020
Abstract: This paper aims to give an overview of the technique of energy-filtered transmission electron microscopy (EFTEM). It explains the basic principles of the technique and points to the relevant literature for more detailed issues. Experimental examples are given to show the power of EFTEM to study the chemical composition of nanoscale samples in materials science. Advanced EFTEM applications like imaging spectroscopy and EFTEM tomography are briefly discussed. (C) 2004 Elsevier B.V. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 3.241
Times cited: 37
DOI: 10.1016/j.sab.2004.03.020
|
“Structural characterization of Nb-TiO2 nanosized thick-films for gas sensing application”. Ferroni M, Carotta MC, Guidi V, Martinelli G, Ronconi F, Richard O, van Dyck D, van Landuyt J, Sensors and actuators : B : chemical 68, 140 (2000). http://doi.org/10.1016/S0925-4005(00)00474-3
Abstract: Pure and Nb-doped TiO2 thick-films were prepared by screen-printing, starting from nanosized powders. Grain growth and crystalline phase modification occurred as consequence of firing at high temperature. It has been shown that niobium addition inhibits grain coarsening and hinders anatase-to-rutile phase transition. These semiconducting films exhibited n-type behavior, while Nb acted as donor-dopant. Gas measurements demonstrated that the films are suitable for CO or NO2 sensing. Microstructural characterization by electron microscopy and differential thermal analysis (DTA) highlights the dependence of gas-sensing behavior on film's properties. (C) 2000 Elsevier Science S.A. All rights reserved.
Keywords: P1 Proceeding; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 5.401
Times cited: 51
DOI: 10.1016/S0925-4005(00)00474-3
|
“Hollow Cone Electron Imaging for Single Particle 3D Reconstruction of Proteins”. Tsai C-Y, Chang Y-C, Lobato I, Van Dyck D, Chen F-R, Scientific reports 6, 27701 (2016). http://doi.org/10.1038/srep27701
Abstract: The main bottlenecks for high-resolution biological imaging in electron microscopy are radiation sensitivity and low contrast. The phase contrast at low spatial frequencies can be enhanced by using a large defocus but this strongly reduces the resolution. Recently, phase plates have been developed to enhance the contrast at small defocus but electrical charging remains a problem. Single particle cryo-electron microscopy is mostly used to minimize the radiation damage and to enhance the resolution of the 3D reconstructions but it requires averaging images of a massive number of individual particles. Here we present a new route to achieve the same goals by hollow cone dark field imaging using thermal diffuse scattered electrons giving about a 4 times contrast increase as compared to bright field imaging. We demonstrate the 3D reconstruction of a stained GroEL particle can yield about 13.5 A resolution but using a strongly reduced number of images.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 4.259
DOI: 10.1038/srep27701
|
“Modification of the multislice method for calculating coherent STEM images”. Chen JH, van Dyck D, op de Beeck M, Broeckx J, van Landuyt J, Physica status solidi: A: applied research 150, 13 (1995). http://doi.org/10.1002/pssa.2211500103
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Times cited: 5
DOI: 10.1002/pssa.2211500103
|
“A peculiar diffraction effect in FCC crystals of C60”. Amelinckx S, van Heurck C, van Dyck D, Van Tendeloo G, Physica status solidi: A: applied research 131, 589 (1992). http://doi.org/10.1002/pssa.2211310231
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Times cited: 13
DOI: 10.1002/pssa.2211310231
|
“Electron-diffraction evidence for ordering of interstitial silver ions in silver bromide microcrystals”. Goessens C, Schryvers D, van Dyck D, van Landuyt J, de Keyzer R, Physica status solidi: A 143, 277 (1994). http://doi.org/10.1002/pssa.2211430211
Abstract: The occurrence and origin of diffuse intensity contours in electron micrographs of AgBr crystals are investigated. The observations are interpreted in terms of a model, which attributes diffuse scattering to the presence of predominant atom or vacancy clusters of a particular polyhedral type. It is shown that irrespective of the crystal morphology, interstitial Ag ions order in AgBr material in clusters of finite size along 001 type planes. A different geometry of the diffuse intensity locus observed for triangular and hexagonal tabular grains is explained in terms of the different twin plane morphology of these grains.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Times cited: 7
DOI: 10.1002/pssa.2211430211
|
“Do smaller probes in a scanning transmission electron microscope result in more precise measurement of the distances between atom columns?”.Van Aert S, van Dyck D, Philosophical magazine: B: physics of condensed matter: electronic, optical and magnetic properties 81, 1833 (2001). http://doi.org/10.1080/13642810108223121
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Times cited: 11
DOI: 10.1080/13642810108223121
|
“Artifact Reduction Based on Sinogram Interpolation for the 3D Reconstruction of Nanoparticles Using Electron Tomography”. Sentosun K, Lobato I, Bladt E, Zhang Y, Palenstijn WJ, Batenburg KJ, Van Dyck D, Bals S, Particle and particle systems characterization 34, 1700287 (2017). http://doi.org/10.1002/ppsc.201700287
Abstract: Electron tomography is a well-known technique providing a 3D characterization of the morphology and chemical composition of nanoparticles. However, several reasons hamper the acquisition of tilt series with a large number of projection images, which deteriorate the quality of the 3D reconstruction. Here, an inpainting method that is based on sinogram interpolation is proposed, which enables one to reduce artifacts in the reconstruction related to a limited tilt series of projection images. The advantages of the approach will be demonstrated for the 3D characterization of nanoparticles using phantoms and several case studies.
Keywords: A1 Journal article; Engineering sciences. Technology; Electron microscopy for materials research (EMAT); Vision lab
Times cited: 2
DOI: 10.1002/ppsc.201700287
|
“Resolution of coherent and incoherent imaging systems reconsidered: classical criteria and a statistical alternative”. Van Aert S, van Dyck D, den Dekker AJ, Optics express 14, 3830 (2006). http://doi.org/10.1364/OE.14.003830
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 3.307
Times cited: 45
DOI: 10.1364/OE.14.003830
|
“Up close: Center for Electron Microscopy of Materials Science at the University of Antwerp”. Van Tendeloo G, Schryvers D, van Dyck D, van Landuyt J, Amelinckx S, MRS bulletin , 57 (1994)
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 5.667
|
“Obstacles on the road towards atomic resolution tomography”. van Dyck D, Van Aert S, Croitoru MD, Microscoy and microanalysis 11, 238 (2005)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT); Vision lab
|
“Atomic resolution mapping using quantitative high-angle annular dark field scanning transmission electron microscopy”. Van Aert S, Verbeeck J, Bals S, Erni R, van Dyck D, Van Tendeloo G, Microscopy and microanalysis 15, 464 (2009). http://doi.org/10.1017/S1431927609093957
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.891
Times cited: 1
DOI: 10.1017/S1431927609093957
|
“Fully automated measurement of the modulation transfer function of charge-coupled devices above the Nyquist frequency”. van den Broek W, Van Aert S, van Dyck D, Microscopy and microanalysis 18, 336 (2012). http://doi.org/10.1017/S1431927611012633
Abstract: The charge-coupled devices used in electron microscopy are coated with a scintillating crystal that gives rise to a severe modulation transfer function (MTF). Exact knowledge of the MTF is imperative for a good correspondence between image simulation and experiment. We present a practical method to measure the MTF above the Nyquist frequency from the beam blocker's shadow image. The image processing has been fully automated and the program is made public. The method is successfully tested on three cameras with various beam blocker shapes.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.891
Times cited: 15
DOI: 10.1017/S1431927611012633
|
“Physical limits on atomic resolution”. van Dyck D, Van Aert S, den Dekker AJ, Microscopy and microanalysis 10, 153 (2004). http://doi.org/10.1017/S143192760404036X
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.891
Times cited: 14
DOI: 10.1017/S143192760404036X
|
“Statistical estimation of oxygen atomic positions eith sub Ångstrom precision from exit wave reconstruction”. Bals S, Van Aert S, Van Tendeloo G, van Dyck D, Avila-Brande D, Microscopy and microanalysis 11, 556 (2005)
Keywords: A3 Journal article; Electron microscopy for materials research (EMAT); Vision lab
|
“Do you believe that atoms stay in place when you observe them in HREM?”.van Dyck D, Lobato I, Chen F-R, Kisielowski C, Micron 68, 158 (2015). http://doi.org/10.1016/j.micron.2014.09.003
Abstract: Recent advancements in aberration-corrected electron microscopy allow for an evaluation of unexpectedly large atom displacements beyond a resolution limit of similar to 0.5 angstrom, which are found to be dose-rate dependent in high resolution images. In this paper we outline a consistent description of the electron scattering process, which explains these unexpected phenomena. Our approach links thermal diffuse scattering to electron beam-induced object excitation and relaxation processes, which strongly contribute to the image formation process. The effect can provide an explanation for the well-known contrast mismatch (“Stobbs factor”) between image calculations and experiments. (C) 2014 Elsevier Ltd. All rights reserved.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.98
Times cited: 11
DOI: 10.1016/j.micron.2014.09.003
|
“How to optimize the experimental design of quantitative atomic resolution TEM experiments?”.Van Aert S, den Dekker AJ, van Dyck D, Micron 35, 425 (2004). http://doi.org/10.1016/j.micron.2004.01.007
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.98
Times cited: 14
DOI: 10.1016/j.micron.2004.01.007
|
“Imaging from atomic structure to electronic structure”. Xu Q, Zandbergen HW, van Dyck D, Micron 43, 524 (2012). http://doi.org/10.1016/j.micron.2011.10.024
Abstract: This paper discusses the possibility of retrieving the electron distribution (with highlighted valence electron distribution information) of materials from recorded HREM images. This process can be achieved by solving two inverse problems: reconstruction of the exit wave and reconstruction of the electron distribution from exit waves. The first inverse problem can be solved using a focal series reconstruction method. We show that the second inverse problem can be solved by combining a series of exit waves recorded at different thickness conditions. This process is designed based on an improved understanding of the dynamical scattering process. It also explains the fundamental difficulty of obtaining the valence electron distribution information and the basis of our solution.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.98
DOI: 10.1016/j.micron.2011.10.024
|
“Model-based electron microscopy : from images toward precise numbers for unknown structure parameters”. Van Aert S, van den Broek W, Goos P, van Dyck D, Micron 43, 509 (2012). http://doi.org/10.1016/j.micron.2011.10.019
Abstract: Statistical parameter estimation theory is proposed as a method to quantify electron microscopy images. It aims at obtaining precise and accurate values for the unknown structure parameters including, for example, atomic column positions and types. In this theory, observations are purely considered as data planes, from which structure parameters have to be determined using a parametric model describing the images. The method enables us to measure positions of atomic columns with a precision of the order of a few picometers even though the resolution of the electron microscope is one or two orders of magnitude larger. Moreover, small differences in averaged atomic number, which cannot be distinguished visually, can be quantified using high-angle annular dark field scanning transmission electron microscopy images. Finally, it is shown how to optimize the experimental design so as to attain the highest precision. As an example, the optimization of the probe size for nanoparticle radius measurements is considered. It is also shown how to quantitatively balance signal-to-noise ratio and resolution by adjusting the probe size.
Keywords: A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 1.98
Times cited: 7
DOI: 10.1016/j.micron.2011.10.019
|
“An electron microscopic study of highly oriented undoped and FeCl3-doped poly (p-phenylenevinylene)”. Zhang XB, Van Tendeloo G, van Landuyt J, van Dyck D, Briers J, Bao Y, Geise HJ, Macromolecules 29, 1554 (1996). http://doi.org/10.1021/ma9513067
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 5.8
Times cited: 10
DOI: 10.1021/ma9513067
|
“High-resolution electron microscopy and electron tomography: resolution versus precision”. Van Aert S, den Dekker AJ, van Dyck D, van den Bos A, Journal of structural biology 138, 21 (2002). http://doi.org/10.1016/S1047-8477(02)00016-3
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Impact Factor: 2.767
Times cited: 33
DOI: 10.1016/S1047-8477(02)00016-3
|
“Advanced electron crystallography through model-based imaging”. Van Aert S, De Backer A, Martinez GT, den Dekker AJ, Van Dyck D, Bals S, Van Tendeloo G, IUCrJ 3, 71 (2016). http://doi.org/10.1107/S2052252515019727
Abstract: The increasing need for precise determination of the atomic arrangement of non-periodic structures in materials design and the control of nanostructures explains the growing interest in quantitative transmission electron microscopy. The aim is to extract precise and accurate numbers for unknown structure parameters including atomic positions, chemical concentrations and atomic numbers. For this purpose, statistical parameter estimation theory has been shown to provide reliable results. In this theory, observations are considered purely as data planes, from which structure parameters have to be determined using a parametric model describing the images. As such, the positions of atom columns can be measured with a precision of the order of a few picometres, even though the resolution of the electron microscope is still one or two orders of magnitude larger. Moreover, small differences in average atomic number, which cannot be distinguished visually, can be quantified using high-angle annular dark-field scanning transmission electron microscopy images. In addition, this theory allows one to measure compositional changes at interfaces, to count atoms with single-atom sensitivity, and to reconstruct atomic structures in three dimensions. This feature article brings the reader up to date, summarizing the underlying theory and highlighting some of the recent applications of quantitative model-based transmisson electron microscopy.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab; Engineering Management (ENM)
Impact Factor: 5.793
Times cited: 30
DOI: 10.1107/S2052252515019727
|
“Atomic resolution electron tomography: a dream?”.van Dyck D, Van Aert S, Croitoru M, International journal of materials research 97, 872 (2006). http://doi.org/10.3139/146.101314
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Condensed Matter Theory (CMT); Vision lab
Impact Factor: 0.681
Times cited: 6
DOI: 10.3139/146.101314
|
“Present state of the composition evaluation of ternary semiconductor nanostructures by lattice fringe analysis”. Rosenauer A, Gerthsen D, Van Aert S, van Dyck D, den Dekker AJ, Institute of physics conference series , 19 (2003)
Abstract: Semiconductor heterostructures are used for the fabrication of optoelectronic devices. Performance of such devices is governed by their chemical morphology. The composition distribution of quantum wells and dots is influenced by kinetic growth processes which are not understood completely at present. To obtain more information about these effects, methods for composition determination with a spatial resolution at a near atomic scale are necessary. In this paper we focus on the present state of the composition evaluation by the lattice fringe analysis (CELFA) technique and explain the basic ideas, optimum imaging conditions, precision and accuracy.
Keywords: A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
|