Pub Date : 2026-03-01Epub Date: 2025-11-30DOI: 10.1016/j.ultramic.2025.114292
Ovidiu Cretu, Koji Kimoto
We report on the development of a new 100 MHz high-speed scan controller for the electron microscope, using programmable hardware. By using a spiral scan pattern in order to work around the limitations of the scan coils, we show that this controller is able to acquire undistorted images with a frame time of 0.9 ms. The controller’s scan signal and timing control is used to optimize regular (sawtooth) scanning, in order to reduce image distortions at high speeds. Finally, we implement a dose-driven acquisition method, which lowers the required dose and optimizes its distribution, while maintaining the contrast mechanism of the detector.
{"title":"Development of a 100 MHz scan controller for the electron microscope","authors":"Ovidiu Cretu, Koji Kimoto","doi":"10.1016/j.ultramic.2025.114292","DOIUrl":"10.1016/j.ultramic.2025.114292","url":null,"abstract":"<div><div>We report on the development of a new 100 MHz high-speed scan controller for the electron microscope, using programmable hardware. By using a spiral scan pattern in order to work around the limitations of the scan coils, we show that this controller is able to acquire undistorted images with a frame time of 0.9 ms. The controller’s scan signal and timing control is used to optimize regular (sawtooth) scanning, in order to reduce image distortions at high speeds. Finally, we implement a dose-driven acquisition method, which lowers the required dose and optimizes its distribution, while maintaining the contrast mechanism of the detector.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114292"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145693176","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-18DOI: 10.1016/j.ultramic.2025.114301
Nicolò M. Della Ventura , Kalani Moore , McLean P. Echlin , Matthew R. Begley , Tresa M. Pollock , Marc De Graef , Daniel S. Gianola
Accurate quantification of the energy distribution of backscattered electrons (BSEs) contributing to electron backscatter diffraction (EBSD) patterns remains as an active challenge. This study introduces an energy-resolved EBSD methodology based on a monolithic active pixel sensor direct electron detector and an electron-counting algorithm to enable the energy quantification of individual BSEs, providing direct measurements of electron energy spectra within diffraction patterns. Following detector calibration of the detector signal as a function of primary beam energy, measurements using a 12 keV primary beam on Si(100) reveal a broad BSE energy distribution across the diffraction pattern, extending down to 3 keV. Furthermore, an angular dependence in the weighted average BSE energy is observed, closely matching predictions from Monte Carlo simulations. Pixel-resolved energy maps reveal subtle modulations at Kikuchi band edges, offering insights into the backscattering process. By applying energy filtering within spectral windows as narrow as 2 keV centered on the primary beam energy, significant enhancement in pattern clarity and high-frequency detail is observed. Notably, BSEs in the 9–10 keV range dominate Kikuchi pattern formation, while BSEs in the 2–8 keV range, despite having undergone substantial energy loss, still produce Kikuchi patterns. By enabling energy determination at the single-electron level, this approach introduces a versatile tool-set for expanding the quantitative capabilities of EBSD, thereby offering the potential to deepen the understanding of diffraction contrast mechanisms and to advance the precision of crystallographic measurements.
{"title":"Energy-resolved EBSD using a monolithic direct electron detector","authors":"Nicolò M. Della Ventura , Kalani Moore , McLean P. Echlin , Matthew R. Begley , Tresa M. Pollock , Marc De Graef , Daniel S. Gianola","doi":"10.1016/j.ultramic.2025.114301","DOIUrl":"10.1016/j.ultramic.2025.114301","url":null,"abstract":"<div><div>Accurate quantification of the energy distribution of backscattered electrons (BSEs) contributing to electron backscatter diffraction (EBSD) patterns remains as an active challenge. This study introduces an energy-resolved EBSD methodology based on a monolithic active pixel sensor direct electron detector and an electron-counting algorithm to enable the energy quantification of individual BSEs, providing direct measurements of electron energy spectra within diffraction patterns. Following detector calibration of the detector signal as a function of primary beam energy, measurements using a 12 keV primary beam on Si(100) reveal a broad BSE energy distribution across the diffraction pattern, extending down to 3 keV. Furthermore, an angular dependence in the weighted average BSE energy is observed, closely matching predictions from Monte Carlo simulations. Pixel-resolved energy maps reveal subtle modulations at Kikuchi band edges, offering insights into the backscattering process. By applying energy filtering within spectral windows as narrow as 2 keV centered on the primary beam energy, significant enhancement in pattern clarity and high-frequency detail is observed. Notably, BSEs in the 9–10 keV range dominate Kikuchi pattern formation, while BSEs in the 2–8 keV range, despite having undergone substantial energy loss, still produce Kikuchi patterns. By enabling energy determination at the single-electron level, this approach introduces a versatile tool-set for expanding the quantitative capabilities of EBSD, thereby offering the potential to deepen the understanding of diffraction contrast mechanisms and to advance the precision of crystallographic measurements.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114301"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145791018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-07DOI: 10.1016/j.ultramic.2025.114296
Chang-Gi Lee , Byeong-Gyu Chae , I-Jun Ro , Kyuseon Jang , Nak-Kyoon Kim , Jae-Pyoung Ahn , Eric Woods , Jaemin Ahn , Seong Yong Park , Baptiste Gault , Se-Ho Kim
Atom probe tomography (APT) enables near-atomic-scale, three-dimensional elemental mapping through controlled field evaporation of surface atoms, triggered by the combined application of a DC voltage with either voltage or laser pulses. As selected laser wavelengths in atom probes transitioned from near-infrared (1050–1064 nm) toward shorter wavelengths, such as green (532 nm) and near-ultraviolet (NUV 355 nm), the quality of data improved and the range of analyzable materials expanded significantly. Recently, a new commercial atom probe (Invizo 6000) employing a deep ultraviolet (DUV) laser wavelength of 257.5 nm has been introduced. Invizo 6000 incorporates several new design elements, such as dual laser beam, einzel lens, and flat counter electrode. However, despite these substantial design modifications, systematic studies comparing its performance with conventional local electrode atom probe (LEAP) systems across different classes of materials remain scarce. In this study, various materials, including metals and oxides, were examined using commercial LEAP 5000 and Invizo 6000. The quality of the data obtained from both instruments was systematically evaluated using four key metrics: background levels, detection events, ion detection histograms, and mass-resolving power. Additionally, applying a thin coating to the prepared APT specimens was found to enhance data quality.
{"title":"Performance evaluation of deep-ultraviolet laser-assisted Invizo 6000 and near-ultraviolet laser-assisted LEAP 5000 for a range of material systems","authors":"Chang-Gi Lee , Byeong-Gyu Chae , I-Jun Ro , Kyuseon Jang , Nak-Kyoon Kim , Jae-Pyoung Ahn , Eric Woods , Jaemin Ahn , Seong Yong Park , Baptiste Gault , Se-Ho Kim","doi":"10.1016/j.ultramic.2025.114296","DOIUrl":"10.1016/j.ultramic.2025.114296","url":null,"abstract":"<div><div>Atom probe tomography (APT) enables near-atomic-scale, three-dimensional elemental mapping through controlled field evaporation of surface atoms, triggered by the combined application of a DC voltage with either voltage or laser pulses. As selected laser wavelengths in atom probes transitioned from near-infrared (1050–1064 nm) toward shorter wavelengths, such as green (532 nm) and near-ultraviolet (NUV 355 nm), the quality of data improved and the range of analyzable materials expanded significantly. Recently, a new commercial atom probe (Invizo 6000) employing a deep ultraviolet (DUV) laser wavelength of 257.5 nm has been introduced. Invizo 6000 incorporates several new design elements, such as dual laser beam, einzel lens, and flat counter electrode. However, despite these substantial design modifications, systematic studies comparing its performance with conventional local electrode atom probe (LEAP) systems across different classes of materials remain scarce. In this study, various materials, including metals and oxides, were examined using commercial LEAP 5000 and Invizo 6000. The quality of the data obtained from both instruments was systematically evaluated using four key metrics: background levels, detection events, ion detection histograms, and mass-resolving power. Additionally, applying a thin coating to the prepared APT specimens was found to enhance data quality.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114296"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-11-29DOI: 10.1016/j.ultramic.2025.114280
Lei Yu , Weishi Wan , Xiaodong Yang , Meng Li , Takanori Koshikawa , Masahiko Suzuki , Tsuneo Yasue , Xiuguang Jin , Yoshikazu Takeda , Rudolf M. Tromp , Yaowen Liu , Hans-Joachim Elmers , Wen-Xin Tang
Magnetic structures down to the nanometer scale have drawn increasing attention due to their fundamental interests and potential applications. In general, the magnetic structure of a system tends to stay in the state with the lowest energy as different interactions compete with each other. Here we report the direct observation of a meta-stable Omega state with double vortices of the same circularity in a nanoscale Fe island on a W(110) substrate. The process indicates that this metastable state is formed by two isolated islands merging during annealing, while keeping their original vortex state. Micromagnetic simulations confirm the possibility of this metastable state.
{"title":"Direct observation of meta-stable magnetization states in Fe/W(110) nanostructures","authors":"Lei Yu , Weishi Wan , Xiaodong Yang , Meng Li , Takanori Koshikawa , Masahiko Suzuki , Tsuneo Yasue , Xiuguang Jin , Yoshikazu Takeda , Rudolf M. Tromp , Yaowen Liu , Hans-Joachim Elmers , Wen-Xin Tang","doi":"10.1016/j.ultramic.2025.114280","DOIUrl":"10.1016/j.ultramic.2025.114280","url":null,"abstract":"<div><div>Magnetic structures down to the nanometer scale have drawn increasing attention due to their fundamental interests and potential applications. In general, the magnetic structure of a system tends to stay in the state with the lowest energy as different interactions compete with each other. Here we report the direct observation of a meta-stable Omega state with double vortices of the same circularity in a nanoscale Fe island on a W(110) substrate. The process indicates that this metastable state is formed by two isolated islands merging during annealing, while keeping their original vortex state. Micromagnetic simulations confirm the possibility of this metastable state.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114280"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145693175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Atomic Force Microscopy (AFM), as a scanning probe microscopy technique, has been extensively utilized for nanoscale structural characterization, mechanical property quantification, and in-situ electromagnetic field measurements with high spatial resolution. However, the primary limitations hindering the widespread application of AFM include its relatively low scanning velocity, intricate parameter optimization requirements, and the necessity for highly skilled operators to achieve optimal imaging resolution. In this paper, a novel fuzzy amplitude-modulated PI (Proportional-Integral) control methodology is proposed for AFM adaptive control systems, incorporating dynamically adjusted proportional and integral gain parameters to effectively mitigate measurement inaccuracies. Experimental characterization demonstrates that the proposed fuzzy control scheme effectively confines amplitude error to approximately 60 pm under operational conditions of 10 Hz scan rate and 40 μm scan size. This methodology establishes a systematic framework for optimizing parameter configuration in AFM, while simultaneously addressing the critical challenge of achieving high-speed performance in scanning probe microscopy applications.
{"title":"Fast tapping mode atomic force microscopy based on fuzzy PI controller","authors":"Lijia Ji , Renjie Gui , Jinbo Chen , Xuhui Zhang , Gengliang Chen","doi":"10.1016/j.ultramic.2025.114281","DOIUrl":"10.1016/j.ultramic.2025.114281","url":null,"abstract":"<div><div>Atomic Force Microscopy (AFM), as a scanning probe microscopy technique, has been extensively utilized for nanoscale structural characterization, mechanical property quantification, and in-situ electromagnetic field measurements with high spatial resolution. However, the primary limitations hindering the widespread application of AFM include its relatively low scanning velocity, intricate parameter optimization requirements, and the necessity for highly skilled operators to achieve optimal imaging resolution. In this paper, a novel fuzzy amplitude-modulated PI (Proportional-Integral) control methodology is proposed for AFM adaptive control systems, incorporating dynamically adjusted proportional and integral gain parameters to effectively mitigate measurement inaccuracies. Experimental characterization demonstrates that the proposed fuzzy control scheme effectively confines amplitude error to approximately 60 pm under operational conditions of 10 Hz scan rate and 40 μm scan size. This methodology establishes a systematic framework for optimizing parameter configuration in AFM, while simultaneously addressing the critical challenge of achieving high-speed performance in scanning probe microscopy applications.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114281"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145651725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-09DOI: 10.1016/j.ultramic.2025.114297
M.J. Adriaans, J.P. Hoogenboom, A. Mohammadi-Gheidari
Monochromators are essential components in electron microscopy and spectroscopy for improving spatial and energy resolution. Their use in scanning electron microscopes (SEMs), however, remains limited due to high cost and operational complexity. Using a thin-deflector analysis of a homogeneous electrostatic deflector, we show that conventional monochromators exhibit extreme sensitivity to power-supply drift and mechanical imperfections. Meeting these stringent tolerances typically requires additional correction elements, which further increase system complexity and cost.
We demonstrate that fringe-field deflectors are inherently less sensitive to these limitations. Based on this insight, we propose a simple and cost-effective monochromator architecture relying solely on fringe fields. The design achieves optimal energy resolution by incorporating short-range deceleration lenses surrounding the main deflector, eliminating the need for auxiliary correction elements. Such a fully electrostatic configuration is compatible with MEMS fabrication, offering a compact, robust, and accessible pathway for high-performance energy filtering in SEMs.
{"title":"Basic considerations in the design of an electrostatic electron monochromator","authors":"M.J. Adriaans, J.P. Hoogenboom, A. Mohammadi-Gheidari","doi":"10.1016/j.ultramic.2025.114297","DOIUrl":"10.1016/j.ultramic.2025.114297","url":null,"abstract":"<div><div>Monochromators are essential components in electron microscopy and spectroscopy for improving spatial and energy resolution. Their use in scanning electron microscopes (SEMs), however, remains limited due to high cost and operational complexity. Using a thin-deflector analysis of a homogeneous electrostatic deflector, we show that conventional monochromators exhibit extreme sensitivity to power-supply drift and mechanical imperfections. Meeting these stringent tolerances typically requires additional correction elements, which further increase system complexity and cost.</div><div>We demonstrate that fringe-field deflectors are inherently less sensitive to these limitations. Based on this insight, we propose a simple and cost-effective monochromator architecture relying solely on fringe fields. The design achieves optimal energy resolution by incorporating short-range deceleration lenses surrounding the main deflector, eliminating the need for auxiliary correction elements. Such a fully electrostatic configuration is compatible with MEMS fabrication, offering a compact, robust, and accessible pathway for high-performance energy filtering in SEMs.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114297"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145775870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-11-24DOI: 10.1016/j.ultramic.2025.114284
Austin Irish , Lukas Hrachowina , David Alcer , Magnus Borgström , Rainer Timm
Surface physics play an outsized role in nanostructured electronic devices such as solar cells. Semiconductor nanowires are perfect candidates for advanced solar cells due to their outstanding light absorption properties and their flexibility in axially stacking materials of different doping and band gap. Due to nanowire geometry, however, their surfaces dominate device performance and at the same time are challenging to investigate. Kelvin probe force microscopy (KPFM), an atomic force microscopy (AFM)-based method, provides a unique structural and electrical characterization even in unconventional 3D geometries. We demonstrate a high-resolution, non-destructive AFM technique for directly measuring nanowires within an array and still on their growth substrate. This in situ approach ensures measurement integrity and relevance while preserving the structures for subsequent measurement and processing. When compared with electron beam-induced current, cross-sectional KPFM is both more surface sensitive and less destructive. Utilizing such a cross-sectional approach facilitates rapid and comprehensive characterization of nanoelectronic surfaces.
{"title":"On the Edge: In situ Kelvin probe AFM on InP nanowire arrays","authors":"Austin Irish , Lukas Hrachowina , David Alcer , Magnus Borgström , Rainer Timm","doi":"10.1016/j.ultramic.2025.114284","DOIUrl":"10.1016/j.ultramic.2025.114284","url":null,"abstract":"<div><div>Surface physics play an outsized role in nanostructured electronic devices such as solar cells. Semiconductor nanowires are perfect candidates for advanced solar cells due to their outstanding light absorption properties and their flexibility in axially stacking materials of different doping and band gap. Due to nanowire geometry, however, their surfaces dominate device performance and at the same time are challenging to investigate. Kelvin probe force microscopy (KPFM), an atomic force microscopy (AFM)-based method, provides a unique structural and electrical characterization even in unconventional 3D geometries. We demonstrate a high-resolution, non-destructive AFM technique for directly measuring nanowires within an array and still on their growth substrate. This <em>in situ</em> approach ensures measurement integrity and relevance while preserving the structures for subsequent measurement and processing. When compared with electron beam-induced current, cross-sectional KPFM is both more surface sensitive and less destructive. Utilizing such a cross-sectional approach facilitates rapid and comprehensive characterization of nanoelectronic surfaces.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114284"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145678990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-03-01Epub Date: 2025-12-07DOI: 10.1016/j.ultramic.2025.114300
Yangfan Li , Yue Pan , Xincheng Lei , Weiwei Chen , Yang Shen , Mengshu Ge , Xiaozhi Liu , Dong Su
High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) is a vital tool for characterizing single-atom catalysts (SACs). However, reliable elemental identification of different atoms remains challenging because the signal intensity of HAADF depends strongly on defocus and other imaging parameters, potentially ruining the Z-contrast of atoms at different depths. In this work, we investigated the influence of the vertical position of atoms (defocus), support thickness, interatomic height, convergence, and collection angles via multi-slice simulations on a model system of Fe/Pt atoms on amorphous carbon supports. Our calculation shows that at a convergence angle of 28 mrad, a defocus of 8.5 nm can cause Fe and Pt atoms to be indistinguishable. At a larger convergence angle, this critical indistinguishable defocus can be even shorter. To address this limitation, we propose a Multi-Defocus Fusion (MDF) method, retrieving the Z-contrast from serial images from multiple defocus. Experimental validation on a Fe/Pt SAC sample confirms the effectiveness of MDF, yielding clearly separated intensity histograms corresponding to Fe and Pt atoms. This work presents a robust, easy-to-implement strategy for accurate single-atom identification, offering valuable guidance for the accelerated screening and rational design of high-performance SACs.
{"title":"Differentiation of distinct single atoms via multi‑defocus fusion method","authors":"Yangfan Li , Yue Pan , Xincheng Lei , Weiwei Chen , Yang Shen , Mengshu Ge , Xiaozhi Liu , Dong Su","doi":"10.1016/j.ultramic.2025.114300","DOIUrl":"10.1016/j.ultramic.2025.114300","url":null,"abstract":"<div><div>High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) is a vital tool for characterizing single-atom catalysts (SACs). However, reliable elemental identification of different atoms remains challenging because the signal intensity of HAADF depends strongly on defocus and other imaging parameters, potentially ruining the Z-contrast of atoms at different depths. In this work, we investigated the influence of the vertical position of atoms (defocus), support thickness, interatomic height, convergence, and collection angles via multi-slice simulations on a model system of Fe/Pt atoms on amorphous carbon supports. Our calculation shows that at a convergence angle of 28 mrad, a defocus of 8.5 nm can cause Fe and Pt atoms to be indistinguishable. At a larger convergence angle, this critical indistinguishable defocus can be even shorter. To address this limitation, we propose a Multi-Defocus Fusion (MDF) method, retrieving the Z-contrast from serial images from multiple defocus. Experimental validation on a Fe/Pt SAC sample confirms the effectiveness of MDF, yielding clearly separated intensity histograms corresponding to Fe and Pt atoms. This work presents a robust, easy-to-implement strategy for accurate single-atom identification, offering valuable guidance for the accelerated screening and rational design of high-performance SACs.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114300"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145737641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pixelated differential phase contrast (DPC) is a four-dimensional scanning transmission electron microscopy (4D-STEM) technique in which the position of the transmitted beam is tracked to reconstruct the electromagnetic fields of a sample. Although it can provide (semi-) quantitative information for a range of different applications, the measurements are greatly affected by the microscope’s optical and acquisition settings in terms of sensitivity, accuracy, and spatial resolution, particularly when measuring weak electric fields. Herein, we focus on the nano-beam 4D-STEM configuration and systematically study the way in which all the parameters typically selected by users for pixelated-DPC experiments influence the lowest achievable electric field sensitivity. First, we define the metric by which the sensitivity is assessed, discussing the optimal ranges for parameters including convergence semi-angle, electron dose, and camera length in absence of external field, while also evaluating the effect of the scanning system. Next, the sensitivity and its error are assessed under field-bound conditions, realized by a coplanar capacitor that allows the position of the transmitted beam to be shifted controllably using an external bias. Comparison of the experimental results with finite element method calculations yields quantitative information about the accuracy that can be attained for these measurements, while the effects of microscope drift and sample charging are also discussed. Our findings provide a platform for the quantitative assessment of weak electric fields as calculated by pixelated-DPC experiments, while highlighting the challenges associated with these measurements.
{"title":"Assessing the electric field sensitivity measured by pixelated differential phase contrast imaging in vacuum both in the absence of external fields and under field-bound conditions","authors":"Pierpaolo Ranieri , Reinis Ignatans , Victor Boureau , Vasiliki Tileli","doi":"10.1016/j.ultramic.2025.114307","DOIUrl":"10.1016/j.ultramic.2025.114307","url":null,"abstract":"<div><div>Pixelated differential phase contrast (DPC) is a four-dimensional scanning transmission electron microscopy (4D-STEM) technique in which the position of the transmitted beam is tracked to reconstruct the electromagnetic fields of a sample. Although it can provide (semi-) quantitative information for a range of different applications, the measurements are greatly affected by the microscope’s optical and acquisition settings in terms of sensitivity, accuracy, and spatial resolution, particularly when measuring weak electric fields. Herein, we focus on the nano-beam 4D-STEM configuration and systematically study the way in which all the parameters typically selected by users for pixelated-DPC experiments influence the lowest achievable electric field sensitivity. First, we define the metric by which the sensitivity is assessed, discussing the optimal ranges for parameters including convergence semi-angle, electron dose, and camera length in absence of external field, while also evaluating the effect of the scanning system. Next, the sensitivity and its error are assessed under field-bound conditions, realized by a coplanar capacitor that allows the position of the transmitted beam to be shifted controllably using an external bias. Comparison of the experimental results with finite element method calculations yields quantitative information about the accuracy that can be attained for these measurements, while the effects of microscope drift and sample charging are also discussed. Our findings provide a platform for the quantitative assessment of weak electric fields as calculated by pixelated-DPC experiments, while highlighting the challenges associated with these measurements.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"281 ","pages":"Article 114307"},"PeriodicalIF":2.0,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145884240","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-01Epub Date: 2025-11-11DOI: 10.1016/j.ultramic.2025.114278
Evgenii Vlasov, Wouter Heyvaert, Tom Stoops, Sandra Van Aert, Johan Verbeeck, Sara Bals
Secondary electron (SE) imaging offers a powerful complementary capabilities to conventional scanning transmission electron microscopy (STEM) by providing surface-sensitive, pseudo-3D topographic information. However, contrast interpretation of such images remains empirical due to complex interactions of emitted SE with the magnetic field in the objective field of TEM. Here, we propose an analytical physical model that takes into account the physics of SE emission and interaction of the emitted SEs with magnetic field. This enables more reliable image interpretation and potentially lay the foundation for novel 3D surface reconstruction algorithms.
{"title":"Secondary electron topographical contrast formation in scanning transmission electron microscopy","authors":"Evgenii Vlasov, Wouter Heyvaert, Tom Stoops, Sandra Van Aert, Johan Verbeeck, Sara Bals","doi":"10.1016/j.ultramic.2025.114278","DOIUrl":"10.1016/j.ultramic.2025.114278","url":null,"abstract":"<div><div>Secondary electron (SE) imaging offers a powerful complementary capabilities to conventional scanning transmission electron microscopy (STEM) by providing surface-sensitive, pseudo-3D topographic information. However, contrast interpretation of such images remains empirical due to complex interactions of emitted SE with the magnetic field in the objective field of TEM. Here, we propose an analytical physical model that takes into account the physics of SE emission and interaction of the emitted SEs with magnetic field. This enables more reliable image interpretation and potentially lay the foundation for novel 3D surface reconstruction algorithms.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"280 ","pages":"Article 114278"},"PeriodicalIF":2.0,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145518035","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号