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| Author | Lobato, I.; De Backer, A.; Van Aert, S. | ||||
| Title | Real-time simulations of ADF STEM probe position-integrated scattering cross-sections for single element fcc crystals in zone axis orientation using a densely connected neural network | Type | A1 Journal article | ||
| Year | 2023 | Publication  |
Ultramicroscopy | Abbreviated Journal | Ultramicroscopy |
| Volume | 251 | Issue | Pages | 113769 | |
| Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
| Abstract | Quantification of annular dark field (ADF) scanning transmission electron microscopy (STEM) images in terms of composition or thickness often relies on probe-position integrated scattering cross sections (PPISCS). In order to compare experimental PPISCS with theoretically predicted ones, expensive simulations are needed for a given specimen, zone axis orientation, and a variety of microscope settings. The computation time of such simulations can be in the order of hours using a single GPU card. ADF STEM simulations can be efficiently parallelized using multiple GPUs, as the calculation of each pixel is independent of other pixels. However, most research groups do not have the necessary hardware, and, in the best-case scenario, the simulation time will only be reduced proportionally to the number of GPUs used. In this manuscript, we use a learning approach and present a densely connected neural network that is able to perform real-time ADF STEM PPISCS predictions as a function of atomic column thickness for most common face-centered cubic (fcc) crystals (i.e., Al, Cu, Pd, Ag, Pt, Au and Pb) along [100] and [111] zone axis orientations, root-mean-square displacements, and microscope parameters. The proposed architecture is parameter efficient and yields accurate predictions for the PPISCS values for a wide range of input parameters that are commonly used for aberration-corrected transmission electron microscopes. |
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| Language | Wos | 001011617200001 | Publication Date | 2023-06-01 | |
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 0304-3991 | ISBN | Additional Links | UA library record; WoS full record | |
| Impact Factor | 2.2 | Times cited | Open Access | OpenAccess | |
| Notes | This work was supported by the European Research Council (Grant 770887 PICOMETRICS to S. Van Aert). The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (G034621N and G0A7723N) and a postdoctoral grant to A. De Backer. S. Van Aert acknowledges funding from the University of Antwerp Research fund (BOF), Belgium. | Approved | Most recent IF: 2.2; 2023 IF: 2.843 | ||
| Call Number | EMAT @ emat @c:irua:197275 | Serial | 8812 | ||
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| Author | Denisov, N.; Jannis, D.; Orekhov, A.; Müller-Caspary, K.; Verbeeck, J. | ||||
| Title | Characterization of a Timepix detector for use in SEM acceleration voltage range | Type | A1 Journal article | ||
| Year | 2023 | Publication |
Ultramicroscopy | Abbreviated Journal | Ultramicroscopy |
| Volume | 253 | Issue | Pages | 113777 | |
| Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
| Abstract | Hybrid pixel direct electron detectors are gaining popularity in electron microscopy due to their excellent properties. Some commercial cameras based on this technology are relatively affordable which makes them attractive tools for experimentation especially in combination with an SEM setup. To support this, a detector characterization (Modulation Transfer Function, Detective Quantum Efficiency) of an Advacam Minipix and Advacam Advapix detector in the 15–30 keV range was made. In the current work we present images of Point Spread Function, plots of MTF/DQE curves and values of DQE(0) for these detectors. At low beam currents, the silicon detector layer behaviour should be dominant, which could make these findings transferable to any other available detector based on either Medipix2, Timepix or Timepix3 provided the same detector layer is used. | ||||
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| Language | Wos | 001026912700001 | Publication Date | 2023-06-08 | |
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 0304-3991 | ISBN | Additional Links | UA library record; WoS full record | |
| Impact Factor | 2.2 | Times cited | Open Access | OpenAccess | |
| Notes | The authors acknowledge the financial support of the Research Foundation Flanders (FWO, Belgium) project SBO S000121N. The authors are grateful to Dr. Lobato for productive discussion of methods. | Approved | Most recent IF: 2.2; 2023 IF: 2.843 | ||
| Call Number | EMAT @ emat @c:irua:198258 | Serial | 8815 | ||
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| Author | Şentürk, DG.; Yu, CP.; De Backer, A.; Van Aert, S. | ||||
| Title | Atom counting from a combination of two ADF STEM images | Type | A1 Journal Article | ||
| Year | 2024 | Publication |
Ultramicroscopy | Abbreviated Journal | Ultramicroscopy |
| Volume | 255 | Issue | Pages | 113859 | |
| Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
| Abstract | To understand the structure–property relationship of nanostructures, reliably quantifying parameters, such as the number of atoms along the projection direction, is important. Advanced statistical methodologies have made it possible to count the number of atoms for monotype crystalline nanoparticles from a single ADF STEM image. Recent developments enable one to simultaneously acquire multiple ADF STEM images. Here, we present an extended statistics-based method for atom counting from a combination of multiple statistically independent ADF STEM images reconstructed from non-overlapping annular detector collection regions which improves the accuracy and allows one to retrieve precise atom-counts, especially for images acquired with low electron doses and multiple element structures. | ||||
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| Language | Wos | 001089064200001 | Publication Date | 2023-09-23 | |
| 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 | 2.2 | Times cited | Open Access | OpenAccess | |
| Notes | This work was supported by the European Research Council (Grant 770887 PICOMETRICS to S. Van Aert). The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (G034621N, G0A7723N, and EOS 40007495) and a postdoctoral grant to A. De Backer. S. Van Aert acknowledges funding from the University of Antwerp Research fund (BOF). | Approved | Most recent IF: 2.2; 2024 IF: 2.843 | ||
| Call Number | EMAT @ emat @c:irua:201008 | Serial | 8964 | ||
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| Author | Van den Broek, W.; Jannis, D.; Verbeeck, J. | ||||
| Title | Convexity constraints on linear background models for electron energy-loss spectra | Type | A1 Journal Article | ||
| Year | 2023 | Publication |
Ultramicroscopy | Abbreviated Journal | Ultramicroscopy |
| Volume | 254 | Issue | Pages | 113830 | |
| Keywords | A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ; | ||||
| Abstract | In this paper convexity constraints are derived for a background model of electron energy loss spectra (EELS) that is linear in the fitting parameters. The model outperforms a power-law both on experimental and simulated backgrounds, especially for wide energy ranges, and thus improves elemental quantification results. Owing to the model’s linearity, the constraints can be imposed through fitting by quadratic programming. This has important advantages over conventional nonlinear power-law fitting such as high speed and a guaranteed unique solution without need for initial parameters. As such, the need for user input is significantly reduced, which is essential for unsupervised treatment of large datasets. This is demonstrated on a demanding spectrum image of a semiconductor device sample with a high number of elements over a wide energy range. | ||||
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| Publisher | Place of Publication | Editor | |||
| Language | Wos | Publication Date | 2023-08-15 | ||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 0304-3991 | ISBN | Additional Links | UA library record | |
| Impact Factor | 2.2 | Times cited | Open Access | Not_Open_Access | |
| Notes | ECSEL, 875999 ; Horizon 2020; Horizon 2020 Framework Programme; Electronic Components and Systems for European Leadership; | Approved | Most recent IF: 2.2; 2023 IF: 2.843 | ||
| Call Number | EMAT @ emat @c:irua:200588 | Serial | 8961 | ||
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| Author | Şentürk, D.G.; De Backer, A.; Van Aert, S. | ||||
| Title | Element specific atom counting for heterogeneous nanostructures: Combining multiple ADF STEM images for simultaneous thickness and composition determination | Type | A1 Journal Article | ||
| Year | 2024 | Publication |
Ultramicroscopy | Abbreviated Journal | Ultramicroscopy |
| Volume | 259 | Issue | Pages | 113941 | |
| Keywords | A1 Journal Article; Electron Microscopy for Materials Science (EMAT) ; | ||||
| Abstract | In this paper, a methodology is presented to count the number of atoms in heterogeneous nanoparticles based on the combination of multiple annular dark field scanning transmission electron microscopy (ADF STEM) images. The different non-overlapping annular detector collection regions are selected based on the principles of optimal statistical experiment design for the atom-counting problem. To count the number of atoms, the total intensities of scattered electrons for each atomic column, the so-called scattering cross-sections, are simultaneously compared with simulated library values for the different detector regions by minimising the squared differences. The performance of the method is evaluated for simulated Ni@Pt and Au@Ag core-shell nanoparticles. Our approach turns out to be a dose efficient alternative for the investigation of beam-sensitive heterogeneous materials as compared to the combination of ADF STEM and energy dispersive X-ray spectroscopy. | ||||
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| Language | Wos | Publication Date | 2024-02-19 | ||
| Series Editor | Series Title | Abbreviated Series Title | |||
| Series Volume | Series Issue | Edition | |||
| ISSN | 0304-3991 | ISBN | Additional Links | UA library record | |
| Impact Factor | 2.2 | Times cited | Open Access | OpenAccess | |
| Notes | This work was supported by the European Research Council (Grant 770887 PICOMETRICS to S. Van Aert). The authors acknowledge financial support from the Research Foundation Flanders (FWO, Belgium) through project fundings (G.0346.21N, GOA7723N, and EOS 40007495) and a postdoctoral grant to A. De Backer. S. Van Aert acknowledges funding from the University of Antwerp Research fund (BOF). | Approved | Most recent IF: 2.2; 2024 IF: 2.843 | ||
| Call Number | EMAT @ emat @c:irua:204353 | Serial | 8996 | ||
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| Author | Gao, C.; Hofer, C.; Pennycook, T.J. | ||||
| Title | On central focusing for contrast optimization in direct electron ptychography of thick samples | Type | A1 Journal article | ||
| Year | 2024 | Publication |
Ultramicroscopy | Abbreviated Journal | |
| Volume | 256 | Issue | Pages | 113879-7 | |
| Keywords | A1 Journal article; Electron microscopy for materials research (EMAT) | ||||
| Abstract | Ptychography provides high dose efficiency images that can reveal light elements next to heavy atoms. However, despite ptychography having an otherwise single signed contrast transfer function, contrast reversals can occur when the projected potential becomes strong for both direct and iterative inversion ptychography methods. It has recently been shown that these reversals can often be counteracted in direct ptychography methods by adapting the focus. Here we provide an explanation of why the best contrast is often found with the probe focused to the middle of the sample. The phase contribution due to defocus at each sample slice above and below the central plane in this configuration effectively cancels out, which can prevent contrast reversals when dynamical scattering effects are not overly strong. In addition we show that the convergence angle can be an important consideration for removal of contrast reversals in relatively thin samples. | ||||
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| Language | Wos | 001112166400001 | Publication Date | 2023-11-03 | |
| 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 | 2.2 | Times cited | Open Access | Not_Open_Access | |
| Notes | Approved | Most recent IF: 2.2; 2024 IF: 2.843 | |||
| Call Number | UA @ admin @ c:irua:202029 | Serial | 9066 | ||
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