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Author Madsen, J.; Pennycook, T.J.; Susi, T.
Title ab initio description of bonding for transmission electron microscopy Type A1 Journal article
Year 2021 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 231 Issue Pages (up)
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The simulation of transmission electron microscopy (TEM) images or diffraction patterns is often required to interpret their contrast and extract specimen features. This is especially true for high-resolution phase-contrast imaging of materials, but electron scattering simulations based on atomistic models are widely used in materials science and structural biology. Since electron scattering is dominated by the nuclear cores, the scattering potential is typically described by the widely applied independent atom model. This approximation is fast and fairly accurate, especially for scanning TEM (STEM) annular dark-field contrast, but it completely neglects valence bonding and its effect on the transmitting electrons. However, an emerging trend in electron microscopy is to use new instrumentation and methods to extract the maximum amount of information from each electron. This is evident in the increasing popularity of techniques such as 4D-STEM combined with ptychography in materials science, and cryogenic microcrystal electron diffraction in structural biology, where subtle differences in the scattering potential may be both measurable and contain additional insights. Thus, there is increasing interest in electron scattering simulations based on electrostatic potentials obtained from first principles, mainly via density functional theory, which was previously mainly required for holography. In this Review, we discuss the motivation and basis for these developments, survey the pioneering work that has been published thus far, and give our outlook for the future. We argue that a physically better justified ab initio description of the scattering potential is both useful and viable for an increasing number of systems, and we expect such simulations to steadily gain in popularity and importance.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000744190300006 Publication Date 2021-03-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited Open Access OpenAccess
Notes Approved Most recent IF: 2.843
Call Number UA @ admin @ c:irua:183955 Serial 6850
Permanent link to this record
 
 
Author Egoavil, R.; Gauquelin, N.; Martinez, G.T.; Van Aert, S.; Van Tendeloo, G.; Verbeeck, J.
Title Atomic resolution mapping of phonon excitations in STEM-EELS experiments Type A1 Journal article
Year 2014 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 147 Issue Pages (up) 1-7
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Atomically resolved electron energy-loss spectroscopy experiments are commonplace in modern aberration-corrected transmission electron microscopes. Energy resolution has also been increasing steadily with the continuous improvement of electron monochromators. Electronic excitations however are known to be delocalized due to the long range interaction of the charged accelerated electrons with the electrons in a sample. This has made several scientists question the value of combined high spatial and energy resolution for mapping interband transitions and possibly phonon excitation in crystals. In this paper we demonstrate experimentally that atomic resolution information is indeed available at very low energy losses around 100 meV expressed as a modulation of the broadening of the zero loss peak. Careful data analysis allows us to get a glimpse of what are likely phonon excitations with both an energy loss and gain part. These experiments confirm recent theoretical predictions on the strong localization of phonon excitations as opposed to electronic excitations and show that a combination of atomic resolution and recent developments in increased energy resolution will offer great benefit for mapping phonon modes in real space.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000343157400001 Publication Date 2014-05-29
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 22 Open Access
Notes 246102 IFOX; 278510 VORTEX; 246791 COUNTATOMS; Hercules; 312483 ESTEEM2; esteem2jra3 ECASJO; Approved Most recent IF: 2.843; 2014 IF: 2.436
Call Number UA @ lucian @ c:irua:118332UA @ admin @ c:irua:118332 Serial 177
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Author Dunin-Borkowski, R.E.; Lichte, H.; Tillmann, K.; Van Aert, S.; Van Tendeloo, G.
Title Introduction to a special issue in honour of W. Owen Saxton, David J. Smith and Dirk Van Dyck on the occasion of their 65th birthdays Type Editorial
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 134 Issue Pages (up) 1-1
Keywords Editorial; Electron microscopy for materials research (EMAT)
Abstract
Address
Corporate Author Thesis
Publisher Elsevier science bv Place of Publication Amsterdam Editor
Language Wos 000324474900001 Publication Date 2013-07-24
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 1 Open Access
Notes Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:109917 Serial 1721
Permanent link to this record
 
 
Author Heidari, H.; van den Broek, W.; Bals, S.
Title Quantitative electron tomography : the effect of the three-dimensional point spread function Type A1 Journal article
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 135 Issue Pages (up) 1-5
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The intensity levels in a three-dimensional (3D) reconstruction, obtained by electron tomography, can be influenced by several experimental imperfections. Such artifacts will hamper a quantitative interpretation of the results. In this paper, we will correct for artificial intensity variations by determining the 3D point spread function (PSF) of a tomographic reconstruction based on high angle annular dark field scanning transmission electron microscopy. The large tails of the PSF cause an underestimation of the intensity of smaller particles, which in turn hampers an accurate radius estimate. Here, the error introduced by the PSF is quantified and corrected a posteriori.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000326941500001 Publication Date 2013-06-21
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 6 Open Access
Notes Esteem2; Sunflower; esteem2_jra4 Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:111397 Serial 2756
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Author Kirilenko, D.A.; Brunkov, P.N.
Title Measuring the height-to-height correlation function of corrugation in suspended graphene Type A1 Journal article
Year 2016 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 165 Issue 165 Pages (up) 1-7
Keywords A1 Journal article; Electron Microscopy for Materials Science (EMAT);
Abstract Nanocorrugation of 2D crystals is an important phenomenon since it affects their electronic and mechanical properties. The corrugation may have various sources; one of them is flexural phonons that, in particular, are responsible for the thermal conductivity of graphene. A study of corrugation of just the suspended graphene can reveal much of valuable information on the physics of this complicated phenomenon. At the same time, the suspended crystal nanorelief can hardly be measured directly because of high flexibility of the 2D crystal. Moreover, the relief portion related to rapid out-of-plane oscillations (flexural phonons) is also inaccessible by such measurements. Here we present a technique for measuring the Fourier components of the height-height correlation function H(q) of suspended graphene which includes the effect of flexural phonons. The technique is based on the analysis of electron diffraction patterns. The H(q) is measured in the range of wavevectors q approximately 0.4-4.5nm(-1). At the upper limit of this range H(q) does follow the T/kappaq(4) law. So, we measured the value of suspended graphene bending rigidity kappa=1.2+/-0.4eV at ambient temperature T approximately 300K. At intermediate wave vectors, H(q) follows a slightly weaker exponent than theoretically predicted q(-3.15) but is closer to the results of the molecular dynamics simulation. At low wave vectors, the dependence becomes even weaker, which may be a sign of influence of charge carriers on the dynamics of undulations longer than 10nm. The technique presented can be used for studying physics of flexural phonons in other 2D materials.
Address Ioffe Institute, Politekhnicheskaya ul. 26, 194021 St-Petersburg, Russia; ITMO University, Kronverksky pr. 49, 197101 St. Petersburg, Russia
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Wos 000375946200001 Publication Date 2016-03-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links
Impact Factor 2.843 Times cited 3 Open Access
Notes D.K. thanks the RFBR (Grant no. 16-32-60165) for the partial support of this research. The work was carried out in part at the Joint Research Center “Material Science and Characterization in Advanced Technologies” (St-Petersburg, Russia) under the financial support from the Ministry of Education and Science of the Russian Federation (Agreement 14.621.21.0007, 04.12.2014, id RFMEFI62114X0007, the use of the Jeol JEM-2100F microscope) and at EMAT, Universiteit Antwerpen (Antwerpen, Belgium), (the use of the FEI Tecnai G2 microscope). Approved Most recent IF: 2.843
Call Number EMAT @ emat @ Serial 4124
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Author van den Broek, W.; Rosenauer, A.; Goris, B.; Martinez, G.T.; Bals, S.; Van Aert, S.; van Dyck, D.
Title Correction of non-linear thickness effects in HAADF STEM electron tomography Type A1 Journal article
Year 2012 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 116 Issue Pages (up) 8-12
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract In materials science, high angle annular dark field scanning transmission electron microscopy is often used for tomography at the nanometer scale. In this work, it is shown that a thickness dependent, non-linear damping of the recorded intensities occurs. This results in an underestimated intensity in the interior of reconstructions of homogeneous particles, which is known as the cupping artifact. In this paper, this non-linear effect is demonstrated in experimental images taken under common conditions and is reproduced with a numerical simulation. Furthermore, an analytical derivation shows that these non-linearities can be inverted if the imaging is done quantitatively, thus preventing cupping in the reconstruction.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000304473700002 Publication Date 2012-03-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 67 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2012 IF: 2.470
Call Number UA @ lucian @ c:irua:96558 Serial 518
Permanent link to this record
 
 
Author Lobato, I.; Van Dyck, D.
Title MULTEM : a new multislice program to perform accurate and fast electron diffraction and imaging simulations using graphics processing units with CUDA Type A1 Journal article
Year 2015 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 156 Issue 156 Pages (up) 9-17
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
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.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000361001800003 Publication Date 2015-04-28
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 32 Open Access
Notes Approved Most recent IF: 2.843; 2015 IF: 2.436
Call Number UA @ lucian @ c:irua:127848 Serial 4209
Permanent link to this record
 
 
Author Van Eyndhoven, G.; Kurttepeli, M.; van Oers, C.J.; Cool, P.; Bals, S.; Batenburg, K.J.; Sijbers, J.
Title Pore REconstruction and Segmentation (PORES) method for improved porosity quantification of nanoporous materials Type A1 Journal article
Year 2015 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 148 Issue 148 Pages (up) 10-19
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab; Laboratory of adsorption and catalysis (LADCA)
Abstract Electron tomography is currently a versatile tool to investigate the connection between the structure and properties of nanomaterials. However, a quantitative interpretation of electron tomography results is still far from straightforward. Especially accurate quantification of pore-space is hampered by artifacts introduced in all steps of the processing chain, i.e., acquisition, reconstruction, segmentation and quantification. Furthermore, most common approaches require subjective manual user input. In this paper, the PORES algorithm POre REconstruction and Segmentation is introduced; it is a tailor-made, integral approach, for the reconstruction, segmentation, and quantification of porous nanomaterials. The PORES processing chain starts by calculating a reconstruction with a nanoporous-specific reconstruction algorithm: the Simultaneous Update of Pore Pixels by iterative REconstruction and Simple Segmentation algorithm (SUPPRESS). It classifies the interior region to the pores during reconstruction, while reconstructing the remaining region by reducing the error with respect to the acquired electron microscopy data. The SUPPRESS reconstruction can be directly plugged into the remaining processing chain of the PORES algorithm, resulting in accurate individual pore quantification and full sample pore statistics. The proposed approach was extensively validated on both simulated and experimental data, indicating its ability to generate accurate statistics of nanoporous materials.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000345973000002 Publication Date 2014-08-23
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 7 Open Access OpenAccess
Notes Colouratom; ECAS_Sara; (ROMEO:green; preprint:; postprint:can ; pdfversion:cannot); Approved Most recent IF: 2.843; 2015 IF: 2.436
Call Number c:irua:119083 Serial 2672
Permanent link to this record
 
 
Author Béché, A.; Rouviere, J.L.; Barnes, J.P.; Cooper, D.
Title Strain measurement at the nanoscale : comparison between convergent beam electron diffraction, nano-beam electron diffraction, high resolution imaging and dark field electron holography Type A1 Journal article
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 131 Issue Pages (up) 10-23
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Convergent beam electron diffraction (CBED), nano-beam electron diffraction (NBED or NBD), high resolution imaging (HRTEM and HRSTEM) and dark field electron holography (DFEH or HoloDark) are five TEM based techniques able to quantitatively measure strain at the nanometer scale. In order to demonstrate the advantages and disadvantages of each technique, two samples composed of epitaxial silicon-germanium layers embedded in a silicon matrix have been investigated. The five techniques are then compared in terms of strain precision and accuracy, spatial resolution, field of view, mapping abilities and ease of performance and analysis. (C) 2013 Elsevier By. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000322631200002 Publication Date 2013-04-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 73 Open Access
Notes Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:109774 Serial 3171
Permanent link to this record
 
 
Author Zanaga, D.; Altantzis, T.; Sanctorum, J.; Freitag, B.; Bals, S.
Title An alternative approach for ζ-factor measurement using pure element nanoparticles Type A1 Journal article
Year 2016 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 164 Issue 164 Pages (up) 11-16
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract It is very challenging to measure the chemical composition of hetero nanostructures in a reliable and quantitative manner. Here, we propose a novel and straightforward approach that can be used to quantify energy dispersive X-ray spectra acquired in a transmission electron microscope. Our method is based on a combination of electron tomography and the so-called ζ-factor technique. We will demonstrate the reliability of our approach as well as its applicability by investigating Au-Ag and Au-Pt hetero nanostructures. Given its simplicity, we expect that the method could become a new standard in the field of chemical characterization using electron microscopy.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000373526200002 Publication Date 2016-03-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 19 Open Access OpenAccess
Notes The authors acknowledge financial support from the European Research Council (ERC Starting Grant # 335078-COLOURATOMS) and the European Union under the FP7 (Integrated Infrastructure Initiative N. 312483 – ESTEEM2). The authors would also like to thank Luis M. Liz-Marzán, Ana Sánchez-Iglesias, Stefanos Mourdikoudis and Cristina Fernández-López for sample provision and useful discussions.; esteem2jra4; ECASSara; (ROMEO:green; preprint:; postprint:can ; pdfversion:cannot); Approved Most recent IF: 2.843
Call Number EMAT @ emat @ Serial 4019
Permanent link to this record
 
 
Author Zanaga, D.; Altantzis, T.; Sanctorum, J.; Freitag, B.; Bals, S.
Title An alternative approach for \zeta-factor measurement using pure element nanoparticles Type A1 Journal article
Year 2016 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 164 Issue Pages (up) 11-16
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract It is very challenging to measure the chemical composition of hetero nanostructures in a reliable and quantitative manner. Here, we propose a novel and straightforward approach that can be used to quantify energy dispersive X-ray spectra acquired in a transmission electron microscope. Our method is based on a combination of electron tomography and the so-called zeta-factor technique. We will demonstrate the reliability of our approach as well as its applicability by investigating Au-Ag and Au-Pt hetero nanostructures. Given its simplicity, we expect that the method could become a new standard in the field of chemical characterization using electron microscopy. (C) 2016 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000373526200002 Publication Date 2016-03-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 19 Open Access OpenAccess
Notes ; The authors acknowledge financial support from the European Research Council (ERC Starting Grant # 335078-COLOURATOMS) and the European Union under the FP7 (Integrated Infrastructure Initiative N. 312483 – ESTEEM2). ; ecas_Sara Approved Most recent IF: 2.843
Call Number UA @ lucian @ c:irua:133259 Serial 4439
Permanent link to this record
 
 
Author Martinez, G.T.; Rosenauer, A.; de Backer, A.; Verbeeck, J.; Van Aert, S.
Title Quantitative composition determination at the atomic level using model-based high-angle annular dark field scanning transmission electron microscopy Type A1 Journal article
Year 2014 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 137 Issue Pages (up) 12-19
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract High angle annular dark field scanning transmission electron microscopy (HAADF STEM) images provide sample information which is sensitive to the chemical composition. The image intensities indeed scale with the mean atomic number Z. To some extent, chemically different atomic column types can therefore be visually distinguished. However, in order to quantify the atomic column composition with high accuracy and precision, model-based methods are necessary. Therefore, an empirical incoherent parametric imaging model can be used of which the unknown parameters are determined using statistical parameter estimation theory (Van Aert et al., 2009, [1]). In this paper, it will be shown how this method can be combined with frozen lattice multislice simulations in order to evolve from a relative toward an absolute quantification of the composition of single atomic columns with mixed atom types. Furthermore, the validity of the model assumptions are explored and discussed.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000331092200003 Publication Date 2013-11-09
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 74 Open Access
Notes FWO; FP7; ERC Countatoms; ESTEEM2; esteem2_ta Approved Most recent IF: 2.843; 2014 IF: 2.436
Call Number UA @ lucian @ c:irua:111579UA @ admin @ c:irua:111579 Serial 2749
Permanent link to this record
 
 
Author Béché, A.; Juchtmans, R.; Verbeeck, J.
Title Efficient creation of electron vortex beams for high resolution STEM imaging Type A1 Journal article
Year 2017 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 178 Issue 178 Pages (up) 12-19
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The recent discovery of electron vortex beams carrying quantised angular momentum in the TEM has led to an active field of research, exploring a variety of potential applications including the possibility of mapping magnetic states at the atomic scale. A prerequisite for this is the availability of atomic sized electron vortex beams at high beam current and mode purity. In this paper we present recent progress showing that by making use of the Aharonov-Bohm effect near the tip of a long single domain ferromagnetic Nickel needle, a very efficient aperture for the production of electron vortex beams can be realised. The aperture transmits more than 99% of all electrons and provides a vortex mode purity of up to 92%. Placing this aperture in the condenser plane of a state of the art Cs corrected microscope allows us to demonstrate atomic resolution HAADF STEM images with spatial resolution better than 1 Angstrom, in agreement with theoretical expectations and only slightly inferior to the performance of a non-vortex probe on the same instrument.
Address EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Wos 000403862900003 Publication Date 2016-05-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 30 Open Access OpenAccess
Notes A.B. and J.V. acknowledge funding from the European Research Council under the 7th Framework Program (FP7), ERC Starting Grant No. 278510 VORTEX. J.V. acknowledges funding from FWO project G.0044.13N ('Charge ordering').; ECASJO_; Approved Most recent IF: 2.843
Call Number c:irua:134085 c:irua:134085UA @ admin @ c:irua:134085 Serial 4094
Permanent link to this record
 
 
Author Susi, T.; Madsen, J.; Ludacka, U.; Mortensen, J.J.; Pennycook, T.J.; Lee, Z.; Kotakoski, J.; Kaiser, U.; Meyer, J.C.
Title Efficient first principles simulation of electron scattering factors for transmission electron microscopy Type A1 Journal article
Year 2019 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 197 Issue 197 Pages (up) 16-22
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Electron microscopy is a powerful tool for studying the properties of materials down to their atomic structure. In many cases, the quantitative interpretation of images requires simulations based on atomistic structure models. These typically use the independent atom approximation that neglects bonding effects, which may, however, be measurable and of physical interest. Since all electrons and the nuclear cores contribute to the scattering potential, simulations that go beyond this approximation have relied on computationally highly demanding all-electron calculations. Here, we describe a new method to generate ab initio electrostatic potentials when describing the core electrons by projector functions. Combined with an interface to quantitative image simulations, this implementation enables an easy and fast means to model electron scattering. We compare simulated transmission electron microscopy images and diffraction patterns to experimental data, showing an accuracy equivalent to earlier all-electron calculations at a much lower computational cost.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000456311700003 Publication Date 2018-11-12
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 3 Open Access
Notes Approved Most recent IF: 2.843
Call Number UA @ admin @ c:irua:165938 Serial 6296
Permanent link to this record
 
 
Author Lobato, I.; Van Aert, S.; Verbeeck, J.
Title Progress and new advances in simulating electron microscopy datasets using MULTEM Type A1 Journal article
Year 2016 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 168 Issue 168 Pages (up) 17-27
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract A new version of the open source program MULTEM is presented here. It includes a graphical user interface, tapering truncation of the atomic potential, CPU multithreading functionality, single/double precision calculations, scanning transmission electron microscopy (STEM) simulations using experimental detector sensitivities, imaging STEM (ISTEM) simulations, energy filtered transmission electron microscopy (EFTEM) simulations, STEM electron energy loss spectroscopy (EELS) simulations along with other improvements in the algorithms. We also present a mixed channeling approach for the calculation of inelastic excitations, which allows one to considerably speed up time consuming EFTEM/STEM-EELS calculations.
Address EMAT, University of Antwerp, Department of Physics, Groenenborgerlaan 171, B-2020 Antwerp, Belgium
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Wos 000380754100003 Publication Date 2016-06-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 43 Open Access
Notes The authors acknowledge financial support from the European Union under the Seventh Framework Program under a contract for an Integrated Infrastructure Initiative. Reference No. 312483- ESTEEM2. The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (G.0374.13N, G.0369.15N and G.0368.15N).; esteem2jra3; esteem2na3; esteem2_jra2 Approved Most recent IF: 2.843
Call Number c:irua:134088 c:irua:134088UA @ admin @ c:irua:134088 Serial 4093
Permanent link to this record
 
 
Author Wang, A.; Van Aert, S.; Goos, P.; van Dyck, D.
Title Precision of three-dimensional atomic scale measurements from HRTEM images : what are the limits? Type A1 Journal article
Year 2012 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 114 Issue Pages (up) 20-30
Keywords A1 Journal article; Engineering Management (ENM); Electron microscopy for materials research (EMAT); Vision lab
Abstract In this paper, we investigate to what extent high resolution transmission electron microscopy images can be used to measure the mass, in terms of thickness, and surface profile, corresponding to the defocus offset, of an object at the atomic scale. Therefore, we derive an expression for the statistical precision with which these object parameters can be estimated in a quantitative analysis. Evaluating this expression as a function of the microscope settings allows us to derive the optimal microscope design. Acquiring three-dimensional structure information in terms of thickness turns out to be much more difficult than obtaining two-dimensional information on the projected atom column positions. The attainable precision is found to be more strongly affected by processes influencing the image contrast, such as phonon scattering, than by the specific choice of microscope settings. For a realistic incident electron dose, it is expected that atom columns can be distinguished with single atom sensitivity up to a thickness of the order of the extinction distance. A comparable thickness limit is determined to measure surface steps of one atom. An increase of the electron dose shifts the limiting thickness upward due to an increase in the signal-to-noise ratio.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000301954300003 Publication Date 2012-01-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 5 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2012 IF: 2.470
Call Number UA @ lucian @ c:irua:94116 Serial 2692
Permanent link to this record
 
 
Author Schattschneider, P.; Stöger-Pollach, M.; Löffler, S.; Steiger-Thirsfeld, A.; Hell, J.; Verbeeck, J.
Title Sub-nanometer free electrons with topological charge Type A1 Journal article
Year 2012 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 115 Issue Pages (up) 21-25
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The holographic mask technique is used to create freely moving electrons with quantized angular momentum. With electron optical elements they can be focused to vortices with diameters below the nanometer range. The understanding of these vortex beams is important for many applications. Here, we produce electron vortex beams and compare them to a theory of electrons with topological charge. The experimental results show excellent agreement with simulations. As an immediate application, fundamental experimental parameters like spherical aberration and partial coherence are determined. (C) 2012 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000302962400004 Publication Date 2012-01-30
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 24 Open Access
Notes vortex ECASJO_; Approved Most recent IF: 2.843; 2012 IF: 2.470
Call Number UA @ lucian @ c:irua:98279 Serial 3344
Permanent link to this record
 
 
Author Van den Broek, W.; Rosenauer, A.; Van Aert, S.; Sijbers, J.; van Dyck, D.
Title A memory efficient method for fully three-dimensional object reconstruction with HAADF STEM Type A1 Journal article
Year 2014 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 141 Issue Pages (up) 22-31
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract The conventional approach to object reconstruction through electron tomography is to reduce the three-dimensional problem to a series of independent two-dimensional slice-by-slice reconstructions. However, at atomic resolution the image of a single atom extends over many such slices and incorporating this image as prior knowledge in tomography or depth sectioning therefore requires a fully three-dimensional treatment. Unfortunately, the size of the three-dimensional projection operator scales highly unfavorably with object size and readily exceeds the available computer memory. In this paper, it is shown that for incoherent image formation the memory requirement can be reduced to the fundamental lower limit of the object size, both for tomography and depth sectioning. Furthermore, it is shown through multislice calculations that high angle annular dark field scanning transmission electron microscopy can be sufficiently incoherent for the reconstruction of single element nanocrystals, but that dynamical diffraction effects can cause classification problems if more than one element is present. (C) 2014 Elsevier B.V. All rights reserved.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000335766600004 Publication Date 2014-03-22
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 6 Open Access
Notes ResearchFoundationFlanders(FWO;G.0393.11; G.0064.10;andG.0374.13); European Union Seventh Frame- workProgramme [FP7/2007-2013]under Grant agreement no. 312483 (ESTEEM2).; esteem2jra2; esteem2jra4 Approved Most recent IF: 2.843; 2014 IF: 2.436
Call Number UA @ lucian @ c:irua:117650 Serial 1992
Permanent link to this record
 
 
Author de Backer, A.; Martinez, G.T.; Rosenauer, A.; Van Aert, S.
Title Atom counting in HAADF STEM using a statistical model-based approach : methodology, possibilities, and inherent limitations Type A1 Journal article
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 134 Issue Pages (up) 23-33
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract In the present paper, a statistical model-based method to count the number of atoms of monotype crystalline nanostructures from high resolution high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) images is discussed in detail together with a thorough study on the possibilities and inherent limitations. In order to count the number of atoms, it is assumed that the total scattered intensity scales with the number of atoms per atom column. These intensities are quantitatively determined using model-based statistical parameter estimation theory. The distribution describing the probability that intensity values are generated by atomic columns containing a specific number of atoms is inferred on the basis of the experimental scattered intensities. Finally, the number of atoms per atom column is quantified using this estimated probability distribution. The number of atom columns available in the observed STEM image, the number of components in the estimated probability distribution, the width of the components of the probability distribution, and the typical shape of a criterion to assess the number of components in the probability distribution directly affect the accuracy and precision with which the number of atoms in a particular atom column can be estimated. It is shown that single atom sensitivity is feasible taking the latter aspects into consideration.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000324474900005 Publication Date 2013-05-17
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 48 Open Access
Notes FWO; Esteem2; FP 2007-2013; esteem2_jra2 Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:109916 Serial 162
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Author Tan, H.; Verbeeck, J.; Abakumov, A.; Van Tendeloo, G.
Title Oxidation state and chemical shift investigation in transition metal oxides by EELS Type A1 Journal article
Year 2012 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 116 Issue Pages (up) 24-33
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Transition metal L2,3 electron energy-loss spectra for a wide range of V-, Mn- and Fe-based oxides were recorded and carefully analyzed for their correlation with the formal oxidation states of the transition metal ions. Special attention is paid to obtain an accurate energy scale which provides absolute energy positions for all core-loss edges. The white-line ratio method, chemical shift method, ELNES fitting method, two-parameter method and other methods are compared and their validity is discussed. Both the ELNES fitting method and the chemical shift method have the advantage of a wide application range and good consistency but require special attention to accurately measure the core-loss edge position. The obtained conclusions are of fundamental importance, e.g., for obtaining atomic resolution oxidation state information in modern experiments.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000304473700004 Publication Date 2012-03-10
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 413 Open Access
Notes Fwo Approved Most recent IF: 2.843; 2012 IF: 2.470
Call Number UA @ lucian @ c:irua:96959UA @ admin @ c:irua:96959 Serial 2541
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Author Zhang, X.F.; Zhang, X.B.; Bernaerts, D.; Van Tendeloo, G.; Amelinckx, S.; van Landuyt, J.; Werner, H.
Title A simple preparation method for air-sensitive specimens for transmission electron microscopy demonstrated by Rb6C60 Type A1 Journal article
Year 1994 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 55 Issue Pages (up) 25-30
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract In this paper a particularly simple but efficient method is presented by which samples of alkali-doped C-60 materials or other air-sensitive materials can be prepared and transferred into a transmission electron microscope for direct observations and investigations. Flexible, transparent glove bags are used which are filled to a slight overpressure with dry nitrogen. Under this protective atmosphere, the air-sensitive sample is mounted in the specimen holder and inserted in the vacuum of the electron microscope. Rb6C60 which is prepared and transferred into the microscope in this way has been investigated by transmission electron microscopy (TEM). The results confirm the bcc structure and especially the location of the rubidium atoms.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos A1994PE30800005 Publication Date 2002-10-18
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.436 Times cited 2 Open Access
Notes Approved CHEMISTRY, PHYSICAL 77/144 Q3 # MATHEMATICS, INTERDISCIPLINARY 19/101 Q1 # PHYSICS, ATOMIC, MOLECULAR & CHEMICAL 17/35 Q2 #
Call Number UA @ lucian @ c:irua:10007 Serial 3002
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Author Stefan Löffler; Matthieu Bugnet; Nicolas Gauquelin; Sorin Lazar; Elias Assmann; Karsten Held; Gianluigi A. Botton; Peter Schattschneider
Title Real-space mapping of electronic orbitals Type A1 Journal article
Year 2017 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 177 Issue 177 Pages (up) 26-29
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Electronic states are responsible for most material properties, including chemical bonds, electrical and thermal conductivity, as well as optical and magnetic properties. Experimentally, however, they remain mostly elusive. Here, we report the real-space mapping of selected transitions between p and d states on the Ångström scale in bulk rutile (TiO2) using electron energy-loss spectrometry (EELS), revealing information on individual bonds between atoms. On the one hand, this enables the experimental verification of theoretical predictions about electronic states. On the other hand, it paves the way for directly investigating electronic states under conditions that are at the limit of the current capabilities of numerical simulations such as, e.g., the electronic states at defects, interfaces, and quantum dots.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000401219800004 Publication Date 2017-01-31
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record
Impact Factor 2.843 Times cited Open Access Not_Open_Access
Notes ; St.L. thanks Walid Hetaba for discussions about WIEN2k. St.L. and P.S. thank Ralf Hambach and Ute Kaiser for many valuable discussions. M.B. thanks Vienna University of Technology for travel support. St.L. and P.S. acknowledge financial support by the Austrian Science Fund (FWF) under grant number 1543-N20, SFB F45 FOXSI; St.L. also acknowledges financial support by the Austrian Science Fund (FWF) under grant number J3732-N27. M.B., N.G., S.L. and G.A.B. performed the experimental work at the Canadian Center for Electron Microscopy, a national facility supported by McMaster University and the Natural Sciences and Engineering Research Council of Canada (NSERC). G.A.B. is grateful to NSERC for supporting this work. ; Approved Most recent IF: 2.843
Call Number EMAT @ emat @ c:irua:142201 Serial 4539
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Author van Dyck, D.; Van Aert, S.; den Dekker, A.J.; van den Bos, A.
Title Is atomic resolution transmission electron microscopy able to resolve and refine amorphous structures? Type A1 Journal article
Year 2003 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 98 Issue Pages (up) 27-42
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000186831500003 Publication Date 2003-04-25
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 26 Open Access
Notes Approved Most recent IF: 2.843; 2003 IF: 1.665
Call Number UA @ lucian @ c:irua:47516 Serial 1749
Permanent link to this record
 
 
Author Krause, F.F.; Ahl, J.P.; Tytko, D.; Choi, P.P.; Egoavil, R.; Schowalter, M.; Mehrtens, T.; Müller-Caspary, K.; Verbeeck, J.; Raabe, D.; Hertkorn, J.; Engl, K.; Rosenauer, A.
Title Homogeneity and composition of AlInGaN : a multiprobe nanostructure study Type A1 Journal article
Year 2015 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 156 Issue 156 Pages (up) 29-36
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract The electronic properties of quaternary AlInGaN devices significantly depend on the homogeneity of the alloy. The identification of compositional fluctuations or verification of random-alloy distribution is hence of grave importance. Here, a comprehensive multiprobe study of composition and compositional homogeneity is presented, investigating AlInGaN layers with indium concentrations ranging from 0 to 17 at% and aluminium concentrations between 0 and 39 at% employing high-angle annular dark field scanning electron microscopy (HAADF STEM), energy dispersive X-ray spectroscopy (EDX) and atom probe tomography (APT). EDX mappings reveal distributions of local concentrations which are in good agreement with random alloy atomic distributions. This was hence investigated with HAADF STEM by comparison with theoretical random alloy expectations using statistical tests. To validate the performance of these tests, HAADF STEM image simulations were carried out for the case of a random-alloy distribution of atoms and for the case of In-rich clusters with nanometer dimensions. The investigated samples, which were grown by metal-organic vapor phase epitaxy (MOVPE), were thereby found to be homogeneous on this nanometer scale. Analysis of reconstructions obtained from APT measurements yielded matching results. Though HAADF STEM only allows for the reduction of possible combinations of indium and aluminium concentrations to the proximity of isolines in the two-dimensional composition space. The observed ranges of composition are in good agreement with the EDX and APT results within the respective precisions.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000361001800006 Publication Date 2015-04-26
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 11 Open Access
Notes 312483 Esteem2; esteem2_ta Approved Most recent IF: 2.843; 2015 IF: 2.436
Call Number c:irua:126965 c:irua:126965UA @ admin @ c:irua:126965 Serial 1485
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Author Grieb, T.; Tewes, M.; Schowalter, M.; Müller-Caspary, K.; Krause, F.F.; Mehrtens, T.; Hartmann, J.-M.; Rosenauer, A.
Title Quantitative HAADF STEM of SiGe in presence of amorphous surface layers from FIB preparation Type A1 Journal article
Year 2018 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 184 Issue B Pages (up) 29-36
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract <script type='text/javascript'>document.write(unpmarked('The chemical composition of four Si1-xGex layers grown on silicon was determined from quantitative scanning transmission electron microscopy (STEM). The chemical analysis was performed by a comparison of the high-angle annular dark field (HAADF) intensity with multislice simulations. It could be shown that amorphous surface layers originating from the preparation process by focused-ion beam (FIB) at 30 kV have a strong influence on the quantification: the local specimen thickness is overestimated by approximately a factor of two, and the germanium concentration is substantially underestimated. By means of simulations, the effect of amorphous surface layers on the HAADF intensity of crystalline silicon and germanium is investigated. Based on these simulations, a method is developed to analyze the experimental HAADF-STEM images by taking the influence of the amorphous layers into account which is done by a reduction of the intensities by multiplication with a constant factor. This suggested modified HAADF analysis gives germanium concentrations which are in agreement with the nominal values. The same TEM lamella was treated with low-voltage ion milling which removed the amorphous surface layers completely. The results from subsequent quantitative HAADF analyses are in agreement with the nominal concentrations which validates the applicability of the used frozen-lattice based multislice simulations to describe the HAADF scattering of Si1-xGex in STEM. (C) 2017 Elsevier B.V. All rights reserved.'));
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000417779800004 Publication Date 2017-10-14
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 7 Open Access Not_Open_Access
Notes ; This work was supported by the German Research Foundation (DFG) under Contract No. RO2057/11-1. ; Approved Most recent IF: 2.843
Call Number UA @ lucian @ c:irua:148500 Serial 4893
Permanent link to this record
 
 
Author den Dekker, A.J.; Gonnissen, J.; de Backer, A.; Sijbers, J.; Van Aert, S.
Title Estimation of unknown structure parameters from high-resolution (S)TEM images : what are the limits? Type A1 Journal article
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 134 Issue Pages (up) 34-43
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract Statistical parameter estimation theory is proposed as a quantitative method to measure unknown structure parameters from electron microscopy images. Images are then purely considered as data planes from which structure parameters have to be determined as accurately and precisely as possible using a parametric statistical model of the observations. For this purpose, an efficient algorithm is proposed for the estimation of atomic column positions and intensities from high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. Furthermore, the so-called CramérRao lower bound (CRLB) is reviewed to determine the limits to the precision with which continuous parameters such as atomic column positions and intensities can be estimated. Since this lower bound can only be derived for continuous parameters, alternative measures using the principles of detection theory are introduced for problems concerning the estimation of discrete parameters such as atomic numbers. An experimental case study is presented to show the practical use of these measures for the optimization of the experiment design if the purpose is to decide between the presence of specific atom types using STEM images.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000324474900006 Publication Date 2013-06-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 31 Open Access
Notes FWO; FP 2007-2013; Esteem2; esteem2_jra2 Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:109240 Serial 1083
Permanent link to this record
 
 
Author Verbeeck, J.; Béché, A.; van den Broek, W.
Title A holographic method to measure the source size broadening in STEM Type A1 Journal article
Year 2012 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 120 Issue Pages (up) 35-40
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Source size broadening is an important resolution limiting effect in modern STEM experiments. Here, we propose an alternative method to measure the source size broadening making use of a holographic biprism to create interference patterns in an empty Ronchigram. This allows us to measure the exact shape of the source size broadening with a much better sampling than previously possible. We find that the shape of the demagnified source deviates considerably from a Gaussian profile that is often assumed. We fit the profile with a linear combination of a Gaussian and a bivariate Cauchy distribution showing that even though the full width at half maximum is similar to previously reported measurements, the tails of the profile are considerable wider. This is of fundamental importance for quantitative comparison of STEM simulations with experiments as these tails make the image contrast dependent on the interatomic distance, an effect that cannot be reproduced by a single Gaussian profile of fixed width alone.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000308082600005 Publication Date 2012-06-01
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 29 Open Access
Notes This work was supported by funding from the European Research Council under the 7th Framework Program (FP7), ERC Grant no. 246791 COUNTATOMS and ERC Starting Grant 278510 VORTEX. The Qu-Ant-EM microscope was partly funded by the Hercules fund from the Flemish Government. W. Van den Broek acknowledges funding from the Condor project, a project under the supervision of the Embedded Systems Institute (ESI) and FEI. This project is partially supported by the Dutch Ministry of Economic Affairs under the BSIK program. ECASJO_; Approved Most recent IF: 2.843; 2012 IF: 2.470
Call Number UA @ lucian @ c:irua:100466UA @ admin @ c:irua:100466 Serial 1483
Permanent link to this record
 
 
Author Lichtert, S.; Verbeeck, J.
Title Statistical consequences of applying a PCA noise filter on EELS spectrum images Type A1 Journal article
Year 2013 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 125 Issue Pages (up) 35-42
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract Principal component analysis (PCA) noise filtering is a popular method to remove noise from experimental electron energy loss (EELS) spectrum images. Here, we investigate the statistical behaviour of this method by applying it on a simulated data set with realistic noise levels. This phantom data set provides access to the true values contained in the data set as well as to many different realizations of the noise. Using least squares fitting and parameter estimation theory, we demonstrate that even though the precision on the estimated parameters can be better as the CramérRao lower bound, a significant bias is introduced which can alter the conclusions drawn from experimental data sets. The origin of this bias is in the incorrect retrieval of the principal loadings for noisy data. Using an expression for the bias and precision of the singular values from literature, we present an evaluation criterion for these singular values based on the noise level and the amount of information present in the data set. This criterion can help to judge when to avoid PCA noise filtering in practical situations. Further we show that constructing elemental maps of PCA noise filtered data using the background subtraction method, does not guarantee an increase in the signal to noise ratio due to correlation of the spectral data as a result of the filtering process.
Address
Corporate Author Thesis
Publisher Place of Publication Amsterdam Editor
Language Wos 000314679700006 Publication Date 2012-10-27
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 54 Open Access
Notes Fwo; Countatoms; Vortex; Esteem 312483; esteem2jra3 ECASJO; Approved Most recent IF: 2.843; 2013 IF: 2.745
Call Number UA @ lucian @ c:irua:105293 Serial 3153
Permanent link to this record
 
 
Author van Aarle, W.; Palenstijn, W.J.; De Beenhouwer, J.; Altantzis, T.; Bals, S.; Batenburg, K.J.; Sijbers, J.
Title The ASTRA Toolbox: A platform for advanced algorithm development in electron tomography Type A1 Journal article
Year 2015 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 157 Issue 157 Pages (up) 35-47
Keywords A1 Journal article; Electron microscopy for materials research (EMAT); Vision lab
Abstract We present the ASTRA Toolbox as an open platform for 3D image reconstruction in tomography. Most of the software tools that are currently used in electron tomography offer limited flexibility with respect to the geometrical parameters of the acquisition model and the algorithms used for reconstruction. The ASTRA Toolbox provides an extensive set of fast and flexible building blocks that can be used to develop advanced reconstruction algorithms, effectively removing these limitations. We demonstrate this flexibility, the resulting reconstruction quality, and the computational efficiency of this toolbox by a series of experiments, based on experimental dual-axis tilt series.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language English Wos 000361002400005 Publication Date 2015-05-06
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991; ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 562 Open Access OpenAccess
Notes The authors acknowledge financial support from the iMinds ICONMetroCT project,the IWT SBO Tom Food project and from the Netherlands Organisation for Scientific Research (NWO),Project no. 639.072.005. Networking support was provided by the EXTREMA COST Action MP 1207. Sara Bals acknowledges financial support from the European Research Council (ERC Starting Grant #335078 COLOURATOMS).; ECAS_Sara; (ROMEO:green; preprint:; postprint:can ; pdfversion:cannot); Approved Most recent IF: 2.843; 2015 IF: 2.436
Call Number c:irua:127834 Serial 3974
Permanent link to this record
 
 
Author Zhong, Z.; Goris, B.; Schoenmakers, R.; Bals, S.; Batenburg, K.J.
Title A bimodal tomographic reconstruction technique combining EDS-STEM and HAADF-STEM Type A1 Journal article
Year 2017 Publication Ultramicroscopy Abbreviated Journal Ultramicroscopy
Volume 174 Issue 174 Pages (up) 35-45
Keywords A1 Journal article; Electron microscopy for materials research (EMAT)
Abstract A three-dimensional (3D) chemical characterization of nanomaterials can be obtained using tomography based on high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) or energy dispersive X-ray spectroscopy (EDS) STEM. These two complementary techniques have both advantages and disadvantages. The Z-contrast images have good image quality but lack robustness in the compositional analysis, while the elemental maps give more element-specific information, but at a low signal-to-noise ratio and a longer exposure time. Our aim is to combine these two types of complementary information in one single tomographic reconstruction process. Therefore, an imaging model is proposed combining both HAADF-STEM

and EDS-STEM. Based on this model, the elemental distributions can be reconstructed using both types of information simultaneously during the reconstruction process. The performance of the new technique is evaluated using simulated data and real experimental data. The results demonstrate that combining two imaging modalities leads to tomographic reconstructions with suppressed noise and enhanced contrast.
Address
Corporate Author Thesis
Publisher Place of Publication Editor
Language Wos 000403342200005 Publication Date 2016-12-11
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0304-3991 ISBN Additional Links UA library record; WoS full record; WoS citing articles
Impact Factor 2.843 Times cited 26 Open Access OpenAccess
Notes This research is supported by the Dutch Technology Foundation STW (http://www.stw.nl/), which is part of the Netherlands Organization for Scientific Research (NWO), and which is partly funded by the Ministry of Economic Affairs, Agriculture and Innovation under project number 13314. It is also supported by the Flemish research foundation (FWO Vlaanderen) by project funding (G038116N) and a postdoctoral research grant to B.G. Funding from the European Research Council (Starting Grant No. COLOURATOMS 335078) is acknowledged by S.B. The authors would like to thank Dr. Bernd Rieger and Dr. Richard Aveyard for useful discussions, and Prof. Dr. Luis M. Liz-Marzan for providing the investigated samples. We also acknowledge COST Action MP1207 for networking support. (ROMEO:green; preprint:; postprint:can ; pdfversion:cannot); saraecas; ECAS_Sara; Approved Most recent IF: 2.843
Call Number EMAT @ emat @ c:irua:141719UA @ admin @ c:irua:141719 Serial 4484
Permanent link to this record