Pub Date : 2025-02-26DOI: 10.1016/j.ultramic.2025.114123
Kristiaan H. Helfferich , Johannes D. Meeldijk , Marijn A. van Huis , Jessi E.S. van der Hoeven , Petra E. de Jongh
Multicomponent nanostructured materials are key amongst others for energy and catalysis applications. The nanoscale proximity of different metals critically determines the performance of these functional materials. However, it is difficult to study the spatial distribution of different elements at the nanoscale, especially achieving a statistically relevant assessment. Additionally, common support materials like metal oxides are sensitive to electron beam damage when using high resolution local techniques, such as transmission electron microscopy. We present a robust strategy to quantitatively assess elemental distributions in 3D nanostructured beam-sensitive samples. Key elements are resin embedding, and elemental co-localisation building on a combination of electron tomography and energy-dispersive X-ray spectroscopy. We showcase the methodology with ∼ 3 nm Pd-Ni nanoparticles supported on mesoporous silica. Epoxy resin-embedding ensured sufficient sample stability under the electron beam for tomography-based quantification of different mano- and mesoscale elemental distributions in these samples. Reliable co-location results were obtained and practical guidelines are provided for acquisition and post-processing, relevant for elemental overlap analysis in multi-metallic samples.
{"title":"Quantifying elemental colocation in nanostructured materials using energy-dispersive X-ray spectroscopy","authors":"Kristiaan H. Helfferich , Johannes D. Meeldijk , Marijn A. van Huis , Jessi E.S. van der Hoeven , Petra E. de Jongh","doi":"10.1016/j.ultramic.2025.114123","DOIUrl":"10.1016/j.ultramic.2025.114123","url":null,"abstract":"<div><div>Multicomponent nanostructured materials are key amongst others for energy and catalysis applications. The nanoscale proximity of different metals critically determines the performance of these functional materials. However, it is difficult to study the spatial distribution of different elements at the nanoscale, especially achieving a statistically relevant assessment. Additionally, common support materials like metal oxides are sensitive to electron beam damage when using high resolution local techniques, such as transmission electron microscopy. We present a robust strategy to quantitatively assess elemental distributions in 3D nanostructured beam-sensitive samples. Key elements are resin embedding, and elemental co-localisation building on a combination of electron tomography and energy-dispersive X-ray spectroscopy. We showcase the methodology with ∼ 3 nm Pd-Ni nanoparticles supported on mesoporous silica. Epoxy resin-embedding ensured sufficient sample stability under the electron beam for tomography-based quantification of different mano- and mesoscale elemental distributions in these samples. Reliable co-location results were obtained and practical guidelines are provided for acquisition and post-processing, relevant for elemental overlap analysis in multi-metallic samples.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"271 ","pages":"Article 114123"},"PeriodicalIF":2.1,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143520927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-24DOI: 10.1016/j.ultramic.2025.114120
William J. Davids, Mengwei He, Huma Bilal, Andrew J. Breen, Simon P. Ringer
Atom probe tomography (APT) is routinely used to investigate nano-scale solute architecture within multicomponent systems. However, there is no consensus on how to best quantify solute clustering within APT data. This contribution leverages recent developments in the field of non-parametric hypothesis testing of nearest-neighbour distributions to address this critical gap. We adapt a goodness-of-fit-type test statistic known as ‘the level of heterogeneity’ to quantitatively discern whether solute distributions exhibit clustering behaviour beyond what would be expected from a random distribution. Further, comparing APT datasets remains difficult due to the inability to directly compare their nearest-neighbour distributions. We present a method that leverages Monte-Carlo simulations, already used to calculate the non-parametric statistic, as a means of comparing APT data. The method is more powerful than comparing datasets through the Pearson coefficient, as is conventionally done.
{"title":"Using non-parametric statistical testing to quantify solute clustering in atom probe reconstructions","authors":"William J. Davids, Mengwei He, Huma Bilal, Andrew J. Breen, Simon P. Ringer","doi":"10.1016/j.ultramic.2025.114120","DOIUrl":"10.1016/j.ultramic.2025.114120","url":null,"abstract":"<div><div>Atom probe tomography (APT) is routinely used to investigate nano-scale solute architecture within multicomponent systems. However, there is no consensus on how to best quantify solute clustering within APT data. This contribution leverages recent developments in the field of non-parametric hypothesis testing of nearest-neighbour distributions to address this critical gap. We adapt a goodness-of-fit-type test statistic known as ‘the level of heterogeneity’ to quantitatively discern whether solute distributions exhibit clustering behaviour beyond what would be expected from a random distribution. Further, comparing APT datasets remains difficult due to the inability to directly compare their nearest-neighbour distributions. We present a method that leverages Monte-Carlo simulations, already used to calculate the non-parametric statistic, as a means of comparing APT data. The method is more powerful than comparing datasets through the Pearson coefficient, as is conventionally done.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"271 ","pages":"Article 114120"},"PeriodicalIF":2.1,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143548520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-16DOI: 10.1016/j.ultramic.2025.114118
Robert M. Glaeser
Biological molecules are easily damaged by high-energy electrons, thus limiting the exposures that can be used to image such specimens by electron microscopy. It is argued here that many-electron, volume-plasmon excitations, which promptly transition into multiple types of single-electron ionization and excitation events, seem to be the predominant cause of damage in such materials. Although reducing the rate at which primary radiolysis occurs would allow one to record images that were much less noisy, many novel proposals for achieving this are unlikely to be realized in the near future, while others are manifestly ill-founded. As a result, the most realistic option currently is to more effectively use the available “budget” of electron exposure, i.e. to further improve the “dose efficiency” by which images are recorded. While progress in that direction is currently under way for both “conventional” (i.e. fixed-beam) and scanning EM, the former is expected to set a high standard for the latter to surpass.
{"title":"Commonsense and common nonsense opinions: PROSPECTS for further reducing beam damage in electron microscopy of radiation-sensitive specimens","authors":"Robert M. Glaeser","doi":"10.1016/j.ultramic.2025.114118","DOIUrl":"10.1016/j.ultramic.2025.114118","url":null,"abstract":"<div><div>Biological molecules are easily damaged by high-energy electrons, thus limiting the exposures that can be used to image such specimens by electron microscopy. It is argued here that many-electron, volume-plasmon excitations, which promptly transition into multiple types of single-electron ionization and excitation events, seem to be the predominant cause of damage in such materials. Although reducing the rate at which primary radiolysis occurs would allow one to record images that were much less noisy, many novel proposals for achieving this are unlikely to be realized in the near future, while others are manifestly ill-founded. As a result, the most realistic option currently is to more effectively use the available “budget” of electron exposure, i.e. to further improve the “dose efficiency” by which images are recorded. While progress in that direction is currently under way for both “conventional” (i.e. fixed-beam) and scanning EM, the former is expected to set a high standard for the latter to surpass.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"271 ","pages":"Article 114118"},"PeriodicalIF":2.1,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-16DOI: 10.1016/j.ultramic.2025.114116
Arda Genc , Justin Marlowe , Anika Jalil , Daniel Belzberg , Libor Kovarik , Phillip Christopher
Accurate and efficient characterization of nanoparticles (NPs), particularly regarding particle size distribution, is essential for advancing our understanding of their structure-property relationship and facilitating their design for various applications. In this study, we introduce a novel two-stage artificial intelligence (AI)-driven workflow for NP analysis that leverages prompt engineering techniques from state-of-the-art single-stage object detection and large-scale vision transformer (ViT) architectures. This methodology is applied to transmission electron microscopy (TEM) and scanning TEM (STEM) images of heterogeneous catalysts, enabling high-resolution, high-throughput analysis of particle size distributions for supported metal catalyst NPs. The model's performance in detecting and segmenting NPs is validated across diverse heterogeneous catalyst systems, including various metals (Ru, Cu, PtCo, and Pt), supports (silica (SiO2), γ-alumina (γ-Al2O3), and carbon black), and particle diameter size distributions with mean and standard deviations ranging from 1.6 ± 0.2 nm to 9.7 ± 4.6 nm. The proposed machine learning (ML) methodology achieved an average F1 overlap score of 0.91 ± 0.01 and demonstrated the ability to disentangle overlapping NPs anchored on catalytic support materials. The segmentation accuracy is further validated using the Hausdorff distance and robust Hausdorff distance metrics, with the 90th percent of the robust Hausdorff distance showing errors within 0.4 ± 0.1 nm to 1.4 ± 0.6 nm. Our AI-assisted NP analysis workflow demonstrates robust generalization across diverse datasets and can be readily applied to similar NP segmentation tasks without requiring costly model retraining.
{"title":"A versatile machine learning workflow for high-throughput analysis of supported metal catalyst particles","authors":"Arda Genc , Justin Marlowe , Anika Jalil , Daniel Belzberg , Libor Kovarik , Phillip Christopher","doi":"10.1016/j.ultramic.2025.114116","DOIUrl":"10.1016/j.ultramic.2025.114116","url":null,"abstract":"<div><div>Accurate and efficient characterization of nanoparticles (NPs), particularly regarding particle size distribution, is essential for advancing our understanding of their structure-property relationship and facilitating their design for various applications. In this study, we introduce a novel two-stage artificial intelligence (AI)-driven workflow for NP analysis that leverages prompt engineering techniques from state-of-the-art single-stage object detection and large-scale vision transformer (ViT) architectures. This methodology is applied to transmission electron microscopy (TEM) and scanning TEM (STEM) images of heterogeneous catalysts, enabling high-resolution, high-throughput analysis of particle size distributions for supported metal catalyst NPs. The model's performance in detecting and segmenting NPs is validated across diverse heterogeneous catalyst systems, including various metals (Ru, Cu, PtCo, and Pt), supports (silica (SiO<sub>2</sub>), γ-alumina (γ-Al<sub>2</sub>O<sub>3</sub>), and carbon black), and particle diameter size distributions with mean and standard deviations ranging from 1.6 ± 0.2 nm to 9.7 ± 4.6 nm. The proposed machine learning (ML) methodology achieved an average F1 overlap score of 0.91 ± 0.01 and demonstrated the ability to disentangle overlapping NPs anchored on catalytic support materials. The segmentation accuracy is further validated using the Hausdorff distance and robust Hausdorff distance metrics, with the 90th percent of the robust Hausdorff distance showing errors within 0.4 ± 0.1 nm to 1.4 ± 0.6 nm. Our AI-assisted NP analysis workflow demonstrates robust generalization across diverse datasets and can be readily applied to similar NP segmentation tasks without requiring costly model retraining.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"271 ","pages":"Article 114116"},"PeriodicalIF":2.1,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509280","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 : 2025-02-09DOI: 10.1016/j.ultramic.2025.114115
Bavley Guerguis, Ramya Cuduvally, Richard J H Morris, Gabriel Arcuri, Brian Langelier, Nabil Bassim
{"title":"Erratum to \"The impact of electric field strength on the accuracy of boron dopant quantification in silicon using atom probe tomography\".","authors":"Bavley Guerguis, Ramya Cuduvally, Richard J H Morris, Gabriel Arcuri, Brian Langelier, Nabil Bassim","doi":"10.1016/j.ultramic.2025.114115","DOIUrl":"https://doi.org/10.1016/j.ultramic.2025.114115","url":null,"abstract":"","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":" ","pages":"114115"},"PeriodicalIF":2.1,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143400325","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 : 2025-01-17DOI: 10.1016/j.ultramic.2025.114105
Maximilian Schiester , Helene Waldl , Katherine P. Rice , Marcus Hans , Daniel Primetzhofer , Nina Schalk , Michael Tkadletz
The impact of the laser wavelength on accuracy in elemental composition analysis in atom probe tomography (APT) was investigated. Three different commercial atom probe systems — LEAP 3000X HR, LEAP 5000 XR, and LEAP 6000 XR — were systematically compared for a TiN model coating studying the effect of shorter laser wavelengths, especially in the deep ultraviolet (DUV) range, on the evaporation behavior. The findings demonstrate that the use of shorter wavelengths enhances the accuracy in elemental composition, while maintaining similar electric field strengths. Thus, thermal effects are reduced, which in turn improves mass resolving power. An important aspect of this research includes the estimation of energy density ratios of the different instruments. The reduction in wavelength is accompanied by increasing energy densities due to smaller laser spot sizes. Furthermore, advancements in the detector technology were studied. Finally, the detector dead-times were determined and dead-zones were evaluated to investigate the ion pile-up behavior in APT measurements of nitrides with the LEAP 6000 XR.
{"title":"Effects of laser wavelength and pulse energy on the evaporation behavior of TiN coatings in atom probe tomography: A multi-instrument study","authors":"Maximilian Schiester , Helene Waldl , Katherine P. Rice , Marcus Hans , Daniel Primetzhofer , Nina Schalk , Michael Tkadletz","doi":"10.1016/j.ultramic.2025.114105","DOIUrl":"10.1016/j.ultramic.2025.114105","url":null,"abstract":"<div><div>The impact of the laser wavelength on accuracy in elemental composition analysis in atom probe tomography (APT) was investigated. Three different commercial atom probe systems — LEAP 3000X HR, LEAP 5000 XR, and LEAP 6000 XR — were systematically compared for a TiN model coating studying the effect of shorter laser wavelengths, especially in the deep ultraviolet (DUV) range, on the evaporation behavior. The findings demonstrate that the use of shorter wavelengths enhances the accuracy in elemental composition, while maintaining similar electric field strengths. Thus, thermal effects are reduced, which in turn improves mass resolving power. An important aspect of this research includes the estimation of energy density ratios of the different instruments. The reduction in wavelength is accompanied by increasing energy densities due to smaller laser spot sizes. Furthermore, advancements in the detector technology were studied. Finally, the detector dead-times were determined and dead-zones were evaluated to investigate the ion pile-up behavior in APT measurements of nitrides with the LEAP 6000 XR.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"270 ","pages":"Article 114105"},"PeriodicalIF":2.1,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143012396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-17DOI: 10.1016/j.ultramic.2025.114106
Jennifer L.W. Carter , Tugce Karakulak Uz , Buhari Ibrahim , Jeffrey S. Pigott , Jerard V. Gordon
The objective of this work was to explore the capabilities of a field emission gun scanning electron microscope (FEG-SEM) equipped with a transmission scanning electron detector (TSEM) and energy dispersive spectroscopy (EDS) to identify nanoscale chemical heterogeneities in a gas atomization reaction synthesis (GARS) steel sample. The results of this analysis were compared to the same study conducted with scanning transmission electron microscopy (STEM) with EDS mapping. TSEM-EDS was performed using the standard spectral analysis approach, i.e., pixel-by-pixel identification of elements from the spectra, and a new principal component analysis approach to detect regions of similar spectra before identifying elemental contributions to each spectrum. It was determined that features over 200 nm were detectable with the TSEM-EDS standard spectra analysis technique but the PCA analysis approach was necessary for observing smaller features that contained trace elements. Monte Carlo simulations indicated that the spatial resolution expected from a 150 nm thick foil was consistent with those observed in experimental analysis. Simulations also confirm that thinner samples enable higher spatial resolution scans although smaller interaction volumes may require longer acquisition times.
{"title":"A comparison of energy dispersive spectroscopy in transmission scanning electron microscopy with scanning transmission electron microscopy","authors":"Jennifer L.W. Carter , Tugce Karakulak Uz , Buhari Ibrahim , Jeffrey S. Pigott , Jerard V. Gordon","doi":"10.1016/j.ultramic.2025.114106","DOIUrl":"10.1016/j.ultramic.2025.114106","url":null,"abstract":"<div><div>The objective of this work was to explore the capabilities of a field emission gun scanning electron microscope (FEG-SEM) equipped with a transmission scanning electron detector (TSEM) and energy dispersive spectroscopy (EDS) to identify nanoscale chemical heterogeneities in a gas atomization reaction synthesis (GARS) steel sample. The results of this analysis were compared to the same study conducted with scanning transmission electron microscopy (STEM) with EDS mapping. TSEM-EDS was performed using the standard spectral analysis approach, i.e., pixel-by-pixel identification of elements from the spectra, and a new principal component analysis approach to detect regions of similar spectra before identifying elemental contributions to each spectrum. It was determined that features over 200 nm were detectable with the TSEM-EDS standard spectra analysis technique but the PCA analysis approach was necessary for observing smaller features that contained trace elements. Monte Carlo simulations indicated that the spatial resolution expected from a 150 nm thick foil was consistent with those observed in experimental analysis. Simulations also confirm that thinner samples enable higher spatial resolution scans although smaller interaction volumes may require longer acquisition times.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"270 ","pages":"Article 114106"},"PeriodicalIF":2.1,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143041510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1016/j.ultramic.2025.114104
Supriya Ghosh, Fengdeng Liu, Sreejith Nair, Rishi Raj, Bharat Jalan, K. Andre Mkhoyan
To fully evaluate the atomic structure, and associated properties of materials using transmission electron microscopy, examination of samples from three non-collinear orientations is needed. This is particularly challenging for thin films and nanoscale devices built on substrates due to limitations with plan-view sample preparation. In this work, a new method for preparation of high-quality, site-specific, plan-view TEM samples from thin-films grown on substrates, is presented and discussed. It is based on using a dual-beam focused ion beam scanning electron microscope (FIB-SEM) system. To demonstrate the method, the samples were prepared from thin films of perovskite oxide BaSnO3 grown on a SrTiO3 substrate and metal oxide IrO2 on a TiO2 substrate, ranging from 20–80 nm in thicknesses using molecular beam epitaxy. While the method is optimized for the thin films, it can be extended to other site-specific plan-view samples and devices build on wafers. Aberration-corrected STEM was used to evaluate the quality of the samples and their applicability for atomic-resolution imaging and analysis.
{"title":"Site-specific plan-view (S)TEM sample preparation from thin films using a dual-beam FIB-SEM","authors":"Supriya Ghosh, Fengdeng Liu, Sreejith Nair, Rishi Raj, Bharat Jalan, K. Andre Mkhoyan","doi":"10.1016/j.ultramic.2025.114104","DOIUrl":"10.1016/j.ultramic.2025.114104","url":null,"abstract":"<div><div>To fully evaluate the atomic structure, and associated properties of materials using transmission electron microscopy, examination of samples from three non-collinear orientations is needed. This is particularly challenging for thin films and nanoscale devices built on substrates due to limitations with plan-view sample preparation. In this work, a new method for preparation of high-quality, site-specific, plan-view TEM samples from thin-films grown on substrates, is presented and discussed. It is based on using a dual-beam focused ion beam scanning electron microscope (FIB-SEM) system. To demonstrate the method, the samples were prepared from thin films of perovskite oxide BaSnO<sub>3</sub> grown on a SrTiO<sub>3</sub> substrate and metal oxide IrO<sub>2</sub> on a TiO<sub>2</sub> substrate, ranging from 20–80 nm in thicknesses using molecular beam epitaxy. While the method is optimized for the thin films, it can be extended to other site-specific plan-view samples and devices build on wafers. Aberration-corrected STEM was used to evaluate the quality of the samples and their applicability for atomic-resolution imaging and analysis.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"270 ","pages":"Article 114104"},"PeriodicalIF":2.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143012410","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}
Scanning transmission electron microscopy (STEM) provides high-resolution visualization of atomic structures as well as various functional imaging modes utilizing phase contrasts. In this study we introduce a semicircular aperture in STEM bright field imaging, which gives a phase contrast transfer function that becomes complex and includes both lower and higher spatial frequency contrast transfer. This approach offers significant advantages over conventional phase plate methods, having no charge accumulation, degradation, or unwanted background noise, which are all problematic in the phase plate material. Also compared to the differential phase contrast or ptychography equipment, this semicircular aperture is far less costly. We apply this approach to visualization of polymer, biological and magnetic samples.
{"title":"Semicircular-aperture illumination scanning transmission electron microscopy","authors":"Akira Yasuhara , Fumio Hosokawa , Sadayuki Asaoka , Teppei Akiyama , Tomokazu Iyoda , Chikako Nakayama , Takumi Sannomiya","doi":"10.1016/j.ultramic.2025.114103","DOIUrl":"10.1016/j.ultramic.2025.114103","url":null,"abstract":"<div><div>Scanning transmission electron microscopy (STEM) provides high-resolution visualization of atomic structures as well as various functional imaging modes utilizing phase contrasts. In this study we introduce a semicircular aperture in STEM bright field imaging, which gives a phase contrast transfer function that becomes complex and includes both lower and higher spatial frequency contrast transfer. This approach offers significant advantages over conventional phase plate methods, having no charge accumulation, degradation, or unwanted background noise, which are all problematic in the phase plate material. Also compared to the differential phase contrast or ptychography equipment, this semicircular aperture is far less costly. We apply this approach to visualization of polymer, biological and magnetic samples.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"270 ","pages":"Article 114103"},"PeriodicalIF":2.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143012408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-01-13DOI: 10.1016/j.ultramic.2024.114101
Christian Zietlow, Jörg K.N. Lindner
Electron energy-loss spectroscopy (EELS) performed in a scanning transmission electron microscope (STEM) is susceptible to noise, just like every other measurement. EELS measurements are also affected by signal blurring, related to the energy distribution of the electron beam and the detector point spread function (PSF). Moreover, the signal blurring caused by the detector introduces correlation effects, which smooth the noise. A general understanding of the noise is essential for evaluating the quality of measurements or for designing more effective post-processing techniques such as deconvolution, which especially in the context of EELS is a common practice to enhance signals. Therefore, we offer theoretical insight into the noise smoothing by convolution and characterize the resulting noise correlations by Pearson coefficients. Additional effects play a role in EELS mapping, where multiple spectra are acquired sequentially at various specimen positions. These three-dimensional datasets are affected by energy drifts of the electron beam, causing spectra to shift relative to each other, and by beam current deviations, which alter their relative proportion. We investigate several energy alignment techniques to correct energy drifts on a sub-channel level and describe the intensity normalization necessary to correct for beam current deviations. Both procedures affect noises and uncertainties of the measurement to various degrees. In this paper, we mathematically derive an applied noise model for EELS measurements, which is straightforward to use. Therefore, we provide the necessary methods to determine the most important noise parameters of the EELS detector enabling users to adapt the model. In summary, we aim to provide a comprehensive understanding of the noises faced in EELS and offer the necessary tools to apply this knowledge in practice.
{"title":"An applied noise model for low-loss EELS maps","authors":"Christian Zietlow, Jörg K.N. Lindner","doi":"10.1016/j.ultramic.2024.114101","DOIUrl":"10.1016/j.ultramic.2024.114101","url":null,"abstract":"<div><div>Electron energy-loss spectroscopy (EELS) performed in a scanning transmission electron microscope (STEM) is susceptible to noise, just like every other measurement. EELS measurements are also affected by signal blurring, related to the energy distribution of the electron beam and the detector point spread function (PSF). Moreover, the signal blurring caused by the detector introduces correlation effects, which smooth the noise. A general understanding of the noise is essential for evaluating the quality of measurements or for designing more effective post-processing techniques such as deconvolution, which especially in the context of EELS is a common practice to enhance signals. Therefore, we offer theoretical insight into the noise smoothing by convolution and characterize the resulting noise correlations by Pearson coefficients. Additional effects play a role in EELS mapping, where multiple spectra are acquired sequentially at various specimen positions. These three-dimensional datasets are affected by energy drifts of the electron beam, causing spectra to shift relative to each other, and by beam current deviations, which alter their relative proportion. We investigate several energy alignment techniques to correct energy drifts on a sub-channel level and describe the intensity normalization necessary to correct for beam current deviations. Both procedures affect noises and uncertainties of the measurement to various degrees. In this paper, we mathematically derive an applied noise model for EELS measurements, which is straightforward to use. Therefore, we provide the necessary methods to determine the most important noise parameters of the EELS detector enabling users to adapt the model. In summary, we aim to provide a comprehensive understanding of the noises faced in EELS and offer the necessary tools to apply this knowledge in practice.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"270 ","pages":"Article 114101"},"PeriodicalIF":2.1,"publicationDate":"2025-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143012394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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