Pub Date : 2025-06-08DOI: 10.1016/j.ultramic.2025.114193
Artur Taszakowski , Ariel Marchlewicz
We present an SEM manual rotary holder equipped with an entomological pin adapter, which allows the free rotation of samples in three axes and guarantees appropriate stability. During imaging, the presented device allows for increased safety when working with fragile and valuable specimens (e.g., holotypes) while maintaining parameters at least as good as previously used techniques. The design of the solution allows it to be integrated with many SEM systems and commercial adapters, significantly increasing its usefulness and versatility. Simultaneously, it does not require additional accessories for manipulation during operation. Additionally, learning to use the proposed solution requires only minor experience. An interesting additional application of the SEM manual rotary holder is its possible usage in other microscopy systems, such as stereoscopic microscopes or even for sample preparation purposes for holding samples.
{"title":"SEM manual rotary holder enhancing sample stability equipped with entomological pin adapter","authors":"Artur Taszakowski , Ariel Marchlewicz","doi":"10.1016/j.ultramic.2025.114193","DOIUrl":"10.1016/j.ultramic.2025.114193","url":null,"abstract":"<div><div>We present an SEM manual rotary holder equipped with an entomological pin adapter, which allows the free rotation of samples in three axes and guarantees appropriate stability. During imaging, the presented device allows for increased safety when working with fragile and valuable specimens (e.g., holotypes) while maintaining parameters at least as good as previously used techniques. The design of the solution allows it to be integrated with many SEM systems and commercial adapters, significantly increasing its usefulness and versatility. Simultaneously, it does not require additional accessories for manipulation during operation. Additionally, learning to use the proposed solution requires only minor experience. An interesting additional application of the SEM manual rotary holder is its possible usage in other microscopy systems, such as stereoscopic microscopes or even for sample preparation purposes for holding samples.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114193"},"PeriodicalIF":2.1,"publicationDate":"2025-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263511","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 : 2025-06-06DOI: 10.1016/j.ultramic.2025.114183
Paweł Urbański, Piotr Szyszka, Tomasz Grzebyk
The article presents a novel nanomaterial-based field electron source intended for use in MEMS (microelectromechanical system). The emitter structure consists of a composite of carbon nanotubes (CNTs) and cross-linked polyvinyl-pyrrolidone (PVP). Its production process is based on the thermo-mechanical extraction method. This source is characterized by a low threshold voltage, high current, high thermal resistance and the possibility of uninterrupted operation for many hours. Due to their ease of forming and high thermal resistance, CNT-PVP composites are perfect as electron sources for MEMS systems. Such emitters perfectly withstand the conditions of anodic bonding without compromising their emission properties after the process.
{"title":"CNT-PVP field electron source formed by thermo-mechanical pulling of carbon nanotubes","authors":"Paweł Urbański, Piotr Szyszka, Tomasz Grzebyk","doi":"10.1016/j.ultramic.2025.114183","DOIUrl":"10.1016/j.ultramic.2025.114183","url":null,"abstract":"<div><div>The article presents a novel nanomaterial-based field electron source intended for use in MEMS (microelectromechanical system). The emitter structure consists of a composite of carbon nanotubes (CNTs) and cross-linked polyvinyl-pyrrolidone (PVP). Its production process is based on the thermo-mechanical extraction method. This source is characterized by a low threshold voltage, high current, high thermal resistance and the possibility of uninterrupted operation for many hours. Due to their ease of forming and high thermal resistance, CNT-PVP composites are perfect as electron sources for MEMS systems. Such emitters perfectly withstand the conditions of anodic bonding without compromising their emission properties after the process.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114183"},"PeriodicalIF":2.1,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144263512","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 : 2025-06-03DOI: 10.1016/j.ultramic.2025.114168
S.B. Bimurzaev, Z.S. Sautbekova
The basic scheme of a transmission electron microscope (TEM) with a mirror objective free of spherical and axial chromatic aberrations, which are the main factors limiting the resolution of electron microscopes, is considered. As an objective, an axisymmetric electrostatic mirror (ASEM), the electrodes of which are coaxial cylinders of equal diameter, separated by gaps of finite width, is considered. Based on previously developed aberration concepts, taking into account relativistic effects, the families of three-electrode ASEM are calculated that satisfy the condition of eliminating spherical and axial chromatic aberrations simultaneously at a fixed focal length and a finite width of the interelectrode gaps. From the whole variety of theoretical data, mirrors have been identified that are most suitable for practical use as an aberration-free TEM mirror objective, the geometric and electrical parameters of which ensure the formation of Gaussian planes of the object and the image outside the mirror field. The dependences of the geometric and electrical parameters of such a mirror objective on the energy of the illuminating beam of relativistic electrons are presented.
{"title":"Transmission electron microscope with a mirror objective free of spherical and axial chromatic aberrations","authors":"S.B. Bimurzaev, Z.S. Sautbekova","doi":"10.1016/j.ultramic.2025.114168","DOIUrl":"10.1016/j.ultramic.2025.114168","url":null,"abstract":"<div><div>The basic scheme of a transmission electron microscope (TEM) with a mirror objective free of spherical and axial chromatic aberrations, which are the main factors limiting the resolution of electron microscopes, is considered. As an objective, an axisymmetric electrostatic mirror (ASEM), the electrodes of which are coaxial cylinders of equal diameter, separated by gaps of finite width, is considered. Based on previously developed aberration concepts, taking into account relativistic effects, the families of three-electrode ASEM are calculated that satisfy the condition of eliminating spherical and axial chromatic aberrations simultaneously at a fixed focal length and a finite width of the interelectrode gaps. From the whole variety of theoretical data, mirrors have been identified that are most suitable for practical use as an aberration-free TEM mirror objective, the geometric and electrical parameters of which ensure the formation of Gaussian planes of the object and the image outside the mirror field. The dependences of the geometric and electrical parameters of such a mirror objective on the energy of the illuminating beam of relativistic electrons are presented.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114168"},"PeriodicalIF":2.1,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144471693","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 : 2025-06-02DOI: 10.1016/j.ultramic.2025.114184
M.A. Stróżyk, F.J. Domínguez-Gutiérrez, K. Mulewska, I. Jóźwik
High-entropy alloys (HEAs) are an emerging class of materials renowned for their exceptional mechanical strength, hardness, and resistance to corrosion and irradiation, making them promising candidates for applications in extreme operating conditions. In this study, the nanomechanical response of a single-grain Cantor CrMnFeCoNi HEA, synthesized in-house, is investigated through nanoindentation testing and characterized using three-dimensional Electron Backscatter Diffraction (3D EBSD) reconstruction. This advanced technique enables high-resolution mapping of geometrically necessary dislocation (GND) density and grain reference orientation deviation (GROD) angles, providing critical insights into localized deformation features and strain gradients. To complement the experimental observations, molecular dynamics (MD) simulations were employed to capture atomistic-scale structural responses, achieving qualitative agreement with mesoscale experimental findings. The integration of 3D EBSD and MD simulations underscores the synergy between advanced experimental characterization and computational modeling, revealing complex dislocation nucleation and evolution mechanisms during nanoindentation. This study highlights the potential of combined multiscale approaches to deepen our understanding of deformation phenomena in HEAs.
{"title":"Multiscale characterization of nanomechanical behavior and dislocation mechanisms in Cantor CrMnFeCoNi HEA using 3D EBSD and atomistic modeling","authors":"M.A. Stróżyk, F.J. Domínguez-Gutiérrez, K. Mulewska, I. Jóźwik","doi":"10.1016/j.ultramic.2025.114184","DOIUrl":"10.1016/j.ultramic.2025.114184","url":null,"abstract":"<div><div>High-entropy alloys (HEAs) are an emerging class of materials renowned for their exceptional mechanical strength, hardness, and resistance to corrosion and irradiation, making them promising candidates for applications in extreme operating conditions. In this study, the nanomechanical response of a single-grain Cantor CrMnFeCoNi HEA, synthesized in-house, is investigated through nanoindentation testing and characterized using three-dimensional Electron Backscatter Diffraction (3D EBSD) reconstruction. This advanced technique enables high-resolution mapping of geometrically necessary dislocation (GND) density and grain reference orientation deviation (GROD) angles, providing critical insights into localized deformation features and strain gradients. To complement the experimental observations, molecular dynamics (MD) simulations were employed to capture atomistic-scale structural responses, achieving qualitative agreement with mesoscale experimental findings. The integration of 3D EBSD and MD simulations underscores the synergy between advanced experimental characterization and computational modeling, revealing complex dislocation nucleation and evolution mechanisms during nanoindentation. This study highlights the potential of combined multiscale approaches to deepen our understanding of deformation phenomena in HEAs.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114184"},"PeriodicalIF":2.1,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144241238","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 : 2025-06-02DOI: 10.1016/j.ultramic.2025.114182
J. Wu , C. Liu , A.J. Wang , Y.Z. Gao , L.T. Fu , Z. Liu , J.L. Dickerson , C.J. Russo , P. Wang
Here we have investigated the potential improvement in imaging vitrified biological specimens with the help of a chromatic aberration (Cc)-corrector. Using a newly developed chromatic aberration-corrected electron cryomicroscope (cryo-EM), the phase contrast micrographs comprising signals from both the zero loss and low energy loss (1-100 eV) channels were used to determine the structure of a pseudorabies virus (PRV). Using an energy selecting, electron energy loss spectrometer after the Cc corrector, datasets were collected separately yet sequentially on the same specimen to allow quantification of the signal in each of the respective channels. Both zero-loss first and low-loss first datasets were acquired. For further comparison, datasets from non-Cc-corrected cryo-EM were also collected. 3D reconstructions of the virus from all 4 above datasets are presented including two maps reconstructed only from electrons having lost 18-28 eV of energy whilst transiting the specimen. Although the amplitude contrast of the signals in the low-loss micrographs is opposite in sign to that of typical defocused images using only elastically scattered electrons, we show that the inelastic maps also contain detailed structural information which can be recovered using Cc correction. This can be verified by comparing the maps from each of the channels. Interestingly, the resolution of the reconstructed volume from the low-loss electrons decreases with defocus independently of the purely elastic electron images taken from the same specimen, which is consistent with previous theoretical predictions and experimental measurements of specimen induced decoherence using room temperature test specimens. Together, these results indicate that the inelastically scattered electrons do indeed contain useful phase contrast signals, particularly for thick specimens, but their recovery requires imaging as close to in-focus as possible. Combing the optical correction demonstrated here, with a lossless phase plate for in focus imaging, may offer the most straightforward way to achieve this in the future.
{"title":"Chromatic aberration (Cc) corrected cryo-EM: The structure of pseudorabies virus (PRV) using both zero-loss and energy loss electrons","authors":"J. Wu , C. Liu , A.J. Wang , Y.Z. Gao , L.T. Fu , Z. Liu , J.L. Dickerson , C.J. Russo , P. Wang","doi":"10.1016/j.ultramic.2025.114182","DOIUrl":"10.1016/j.ultramic.2025.114182","url":null,"abstract":"<div><div>Here we have investigated the potential improvement in imaging vitrified biological specimens with the help of a chromatic aberration (Cc)-corrector. Using a newly developed chromatic aberration-corrected electron cryomicroscope (cryo-EM), the phase contrast micrographs comprising signals from both the zero loss and low energy loss (1-100 eV) channels were used to determine the structure of a pseudorabies virus (PRV). Using an energy selecting, electron energy loss spectrometer after the Cc corrector, datasets were collected separately yet sequentially on the same specimen to allow quantification of the signal in each of the respective channels. Both zero-loss first and low-loss first datasets were acquired. For further comparison, datasets from non-Cc-corrected cryo-EM were also collected. 3D reconstructions of the virus from all 4 above datasets are presented including two maps reconstructed only from electrons having lost 18-28 eV of energy whilst transiting the specimen. Although the amplitude contrast of the signals in the low-loss micrographs is opposite in sign to that of typical defocused images using only elastically scattered electrons, we show that the inelastic maps also contain detailed structural information which can be recovered using Cc correction. This can be verified by comparing the maps from each of the channels. Interestingly, the resolution of the reconstructed volume from the low-loss electrons decreases with defocus independently of the purely elastic electron images taken from the same specimen, which is consistent with previous theoretical predictions and experimental measurements of specimen induced decoherence using room temperature test specimens. Together, these results indicate that the inelastically scattered electrons do indeed contain useful phase contrast signals, particularly for thick specimens, but their recovery requires imaging as close to in-focus as possible. Combing the optical correction demonstrated here, with a lossless phase plate for in focus imaging, may offer the most straightforward way to achieve this in the future.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114182"},"PeriodicalIF":2.1,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144241239","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 : 2025-06-01DOI: 10.1016/j.ultramic.2025.114181
T. Maekawa , Y. Kohno , A. Yasuhara , S. Morishita , T. Inoue , Y. Ueda , K. Arakawa
The successful development of a magnetic field-free objective lens for high-resolution imaging has enabled the acquisition of atomic-resolution scanning transmission electron microscopy (STEM) images under magnetic field-free conditions around the sample. Utilizing this magnetic field-free objective lens for conventional transmission electron microscopy (TEM) observations is expected to offer advantages for the comprehensive characterization of magnetic materials. This approach is particularly significant in the context of in-situ observations. To obtain conventional TEM images, such as bright- and dark-field images, it is important to position the objective lens aperture in a diffraction plane, typically the back focal plane of the objective lens. However, positioning the objective lens aperture around the back focal plane, which is surrounded by multiple magnetic poles, is not feasible for the magnetic field-free objective lens. In this study, we describe the development of an image-forming system that can position the aperture in a diffraction plane conjugate to the back focal plane. In addition, the development of a wide-gap pole piece for the magnetic field-free objective lens has enabled the use of sample holders with thick tips for in-situ observations. The magnetic field-free electron microscope, which integrates a newly developed pole piece and image-forming system with higher-order aberration correctors, offers not only atomic-resolution TEM/STEM observations but also a versatile approach for the characterization of magnetic materials in a magnetic field-free environment.
{"title":"Development of an image-forming system for the magnetic field-free electron microscope","authors":"T. Maekawa , Y. Kohno , A. Yasuhara , S. Morishita , T. Inoue , Y. Ueda , K. Arakawa","doi":"10.1016/j.ultramic.2025.114181","DOIUrl":"10.1016/j.ultramic.2025.114181","url":null,"abstract":"<div><div>The successful development of a magnetic field-free objective lens for high-resolution imaging has enabled the acquisition of atomic-resolution scanning transmission electron microscopy (STEM) images under magnetic field-free conditions around the sample. Utilizing this magnetic field-free objective lens for conventional transmission electron microscopy (TEM) observations is expected to offer advantages for the comprehensive characterization of magnetic materials. This approach is particularly significant in the context of <em>in-situ</em> observations. To obtain conventional TEM images, such as bright- and dark-field images, it is important to position the objective lens aperture in a diffraction plane, typically the back focal plane of the objective lens. However, positioning the objective lens aperture around the back focal plane, which is surrounded by multiple magnetic poles, is not feasible for the magnetic field-free objective lens. In this study, we describe the development of an image-forming system that can position the aperture in a diffraction plane conjugate to the back focal plane. In addition, the development of a wide-gap pole piece for the magnetic field-free objective lens has enabled the use of sample holders with thick tips for <em>in-situ</em> observations. The magnetic field-free electron microscope, which integrates a newly developed pole piece and image-forming system with higher-order aberration correctors, offers not only atomic-resolution TEM/STEM observations but also a versatile approach for the characterization of magnetic materials in a magnetic field-free environment.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114181"},"PeriodicalIF":2.1,"publicationDate":"2025-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144205703","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 : 2025-05-25DOI: 10.1016/j.ultramic.2025.114179
Le Liu, Ke Wei, Ke-Xin Bao, Ji-Yu Xie, Xiao-Yi Wang
Anastatus orientalis (Hymenoptera: Eupelmidae) is an egg parasitoid of the internationally quarantined pest Lycorma delicatula, and can be used as a potential biological control agent in practice. Antennae are the important olfactory organs that play a key role in host-parasitoid chemical communication. Therefore, recognition of morphological features is crucial for investigating the olfactory behavior mechanism of parasitic wasps. Here, we observed the ultrastructure of sensilla on the antennae in male and female wasps of A. orientalis using scanning electron microscope. Our results revealed that the antennae of A. orientalis are geniculate, with 13 segments in female wasps and 10 segments in males. The average length of female antennae (1761.17 ± 60.77) μm was shorter than that of males (1883.06 ± 95.68) μm. Ten morphological types of antennal sensilla were found on A. orientalis antennae, including sensilla trichodea (ST), sensilla chaetica (SC), sensilla basiconica (SB), i-type sensilla (IS), corneous sensilla (CS), sensilla campaniformia (Ca), sensilla placodea (Pl), lance sensilla (LS), sensilla coeloconica (Co), and böhm bristles (BBs). Among these, ST had two subtypes (ST I and ST II). SC and Pl were the most abundant sensilla on the antennae of A. orientalis, with wide distribution and large number. Sexual dimorphism was observed in the length, width, abundance, and distribution of sensilla on the antennae. IS were unique to female wasps, suggesting their important role in the recognition and acceptance of host eggs.
{"title":"Ultrastructure of antennal sensilla of Anastatus orientalis (Hymenoptera: Eupelmidae), an egg parasitoid of the invasive spotted lanternfly, Lycorma delicatula (Hemiptera: Fulgoridae)","authors":"Le Liu, Ke Wei, Ke-Xin Bao, Ji-Yu Xie, Xiao-Yi Wang","doi":"10.1016/j.ultramic.2025.114179","DOIUrl":"10.1016/j.ultramic.2025.114179","url":null,"abstract":"<div><div><em>Anastatus orientalis</em> (Hymenoptera: Eupelmidae) is an egg parasitoid of the internationally quarantined pest <em>Lycorma delicatula</em>, and can be used as a potential biological control agent in practice. Antennae are the important olfactory organs that play a key role in host-parasitoid chemical communication. Therefore, recognition of morphological features is crucial for investigating the olfactory behavior mechanism of parasitic wasps. Here, we observed the ultrastructure of sensilla on the antennae in male and female wasps of <em>A. orientalis</em> using scanning electron microscope. Our results revealed that the antennae of <em>A. orientalis</em> are geniculate, with 13 segments in female wasps and 10 segments in males. The average length of female antennae (1761.17 ± 60.77) μm was shorter than that of males (1883.06 ± 95.68) μm. Ten morphological types of antennal sensilla were found on <em>A. orientalis</em> antennae, including sensilla trichodea (ST), sensilla chaetica (SC), sensilla basiconica (SB), i-type sensilla (IS), corneous sensilla (CS), sensilla campaniformia (Ca), sensilla placodea (Pl), lance sensilla (LS), sensilla coeloconica (Co), and böhm bristles (BBs). Among these, ST had two subtypes (ST I and ST II). SC and Pl were the most abundant sensilla on the antennae of <em>A. orientalis</em>, with wide distribution and large number. Sexual dimorphism was observed in the length, width, abundance, and distribution of sensilla on the antennae. IS were unique to female wasps, suggesting their important role in the recognition and acceptance of host eggs.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114179"},"PeriodicalIF":2.1,"publicationDate":"2025-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144196496","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 : 2025-05-23DOI: 10.1016/j.ultramic.2025.114167
Olena Tkach, Gerd Schönhense
The strong electric field between the sample and the extractor is at the heart of cathode lenses and a crucial factor for high resolution. However, fields in the range of 3-10 kV/mm can be a source of complications. Local field enhancement at sharp edges or microscopic protrusions of cleaved samples can lead to field emission or flashovers. In addition, slow background electrons drawn into the microscope column contribute to space charge effects. A novel objective configuration, optimized by ray-tracing simulations at energies from a few eV to 6 keV, significantly reduces the field at the sample. One or more annular electrodes concentric to the extractor can shape the electric field in front of the sample. The formation of a ‘gaplens’ reduces the field to values below the 1 kV/mm range. Tuning the field to zero is advantageous for 3D structured samples. Retarding fields repel slow electrons, suppressing space charge effects. The properties of the different lens modes are investigated using ray tracing and determination of aberration coefficients. Despite its much lower electric field, the gaplens mode exhibits smaller aberrations and enables larger fields of view for both momentum and real space imaging. At electric fields as low as 1200 and 880 V/mm, the accessible solid angle interval in the gaplens mode is three times larger than in the extractor mode (with a start energy of 100 eV and a k-resolution of 10-2 Å-1). Due to the elimination of space charge effects in the retarding field mode, XPEEM resolutions in the range of 25 nm are predicted. The ray tracing results are confirmed by the spherical and chromatic aberration coefficients of the real-space and k-space images.
{"title":"Multimode objective lens for momentum microscopy and XPEEM: Theory","authors":"Olena Tkach, Gerd Schönhense","doi":"10.1016/j.ultramic.2025.114167","DOIUrl":"10.1016/j.ultramic.2025.114167","url":null,"abstract":"<div><div>The strong electric field between the sample and the extractor is at the heart of cathode lenses and a crucial factor for high resolution. However, fields in the range of 3-10 kV/mm can be a source of complications. Local field enhancement at sharp edges or microscopic protrusions of cleaved samples can lead to field emission or flashovers. In addition, slow background electrons drawn into the microscope column contribute to space charge effects. A novel objective configuration, optimized by ray-tracing simulations at energies from a few eV to 6 keV, significantly reduces the field at the sample. One or more annular electrodes concentric to the extractor can shape the electric field in front of the sample. The formation of a ‘gaplens’ reduces the field to values below the 1 kV/mm range. Tuning the field to zero is advantageous for 3D structured samples. Retarding fields repel slow electrons, suppressing space charge effects. The properties of the different lens modes are investigated using ray tracing and determination of aberration coefficients. Despite its much lower electric field, the gaplens mode exhibits smaller aberrations and enables larger fields of view for both momentum and real space imaging. At electric fields as low as 1200 and 880 V/mm, the accessible solid angle interval in the gaplens mode is three times larger than in the extractor mode (with a start energy of 100 eV and a <em>k</em>-resolution of 10<sup>-2</sup> Å<sup>-1</sup>). Due to the elimination of space charge effects in the retarding field mode, XPEEM resolutions in the range of 25 nm are predicted. The ray tracing results are confirmed by the spherical and chromatic aberration coefficients of the real-space and <em>k</em>-space images.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114167"},"PeriodicalIF":2.1,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144205668","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 : 2025-05-20DOI: 10.1016/j.ultramic.2025.114169
Matthias Schmitt , Deepnarayan Biswas , Olena Tkach , Olena Fedchenko , Jieyi Liu , Hans-Joachim Elmers , Michael Sing , Ralph Claessen , Tien-Lin Lee , Gerd Schönhense
The three-dimensional recording scheme of time-of-flight momentum microscopes (ToF-MMs) is advantageous for fast mapping of the photoelectron distribution in (E,k) parameter space over the entire Brillouin zone. However, the 2 ns pulse period of most synchrotrons is too short for pure ToF photoelectron spectroscopy. The use of a hemispherical analyzer (HSA) as a pre-filter allows ToF-MM at such high pulse rates. The first HSA & ToF hybrid MM is operated at the soft X-ray branch of beamline I09 at the Diamond Light Source, UK. The photon energy ranges from 105 eV to 2 keV, with circular polarization available for hν ≥ 145 eV. The HSA reduces the transmitted energy band to typically 0.5 eV, which is then further analyzed by ToF recording. In initial experiments, the overall efficiency gain when switching from the standard 2D (kx,ky) mode to the 3D (kx,ky,Ekin) hybrid mode was about 24. This value is determined by the number of resolved kinetic energies (here 12) and the transmission gain of the electron optics due to the high pass energy of the HSA in hybrid mode (Epass up to 500 eV). The transmission gain depends on the size of the photon footprint on the sample. Under k-imaging conditions, the energy and momentum resolution are 10.2 meV (FWHM) (4.2 meV with 200 μm slits and Epass = 8 eV) and 0.010 Å-1. The energy filtered X-PEEM mode showed a spatial resolution of 250 nm. As examples, we show 2D band mapping of bilayer graphene, 3D mapping of the Fermi surface of Cu, circular dichroic ARPES for intercalated indenene layers, and the sp valence band of Au. Full-field photoelectron diffraction patterns of Ge show rich structure in k-field diameters of up to 6 Å-1.
{"title":"Momentum microscopy with combined hemispherical and time-of-flight electron analyzers at the soft X-ray beamline I09 of the diamond light source","authors":"Matthias Schmitt , Deepnarayan Biswas , Olena Tkach , Olena Fedchenko , Jieyi Liu , Hans-Joachim Elmers , Michael Sing , Ralph Claessen , Tien-Lin Lee , Gerd Schönhense","doi":"10.1016/j.ultramic.2025.114169","DOIUrl":"10.1016/j.ultramic.2025.114169","url":null,"abstract":"<div><div>The three-dimensional recording scheme of time-of-flight momentum microscopes (ToF-MMs) is advantageous for fast mapping of the photoelectron distribution in (<em>E</em>,<strong><em>k</em></strong>) parameter space over the entire Brillouin zone. However, the 2 ns pulse period of most synchrotrons is too short for pure ToF photoelectron spectroscopy. The use of a hemispherical analyzer (HSA) as a pre-filter allows ToF-MM at such high pulse rates. The first HSA & ToF hybrid MM is operated at the soft X-ray branch of beamline I09 at the Diamond Light Source, UK. The photon energy ranges from 105 eV to 2 keV, with circular polarization available for hν ≥ 145 eV. The HSA reduces the transmitted energy band to typically 0.5 eV, which is then further analyzed by ToF recording. In initial experiments, the overall efficiency gain when switching from the standard 2D (<em>k</em><sub>x</sub>,<em>k</em><sub>y</sub>) mode to the 3D (<em>k</em><sub>x</sub>,<em>k</em><sub>y</sub>,<em>E</em><sub>kin</sub>) hybrid mode was about 24. This value is determined by the number of resolved kinetic energies (here 12) and the transmission gain of the electron optics due to the high pass energy of the HSA in hybrid mode (<em>E</em><sub>pass</sub> up to 500 eV). The transmission gain depends on the size of the photon footprint on the sample. Under <em>k</em>-imaging conditions, the energy and momentum resolution are 10.2 meV (FWHM) (4.2 meV with 200 μm slits and <em>E</em><sub>pass</sub> = 8 eV) and 0.010 Å<sup>-1</sup>. The energy filtered X-PEEM mode showed a spatial resolution of 250 nm. As examples, we show 2D band mapping of bilayer graphene, 3D mapping of the Fermi surface of Cu, circular dichroic ARPES for intercalated indenene layers, and the <em>sp</em> valence band of Au. Full-field photoelectron diffraction patterns of Ge show rich structure in <em>k</em>-field diameters of up to 6 Å<sup>-1</sup>.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114169"},"PeriodicalIF":2.1,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144205702","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 : 2025-05-16DOI: 10.1016/j.ultramic.2025.114159
Christian Zietlow, Jörg K.N. Lindner
Electron-energy-loss-spectroscopy (EELS) spectra in the scanning transmission electron microscope (STEM) are affected by various types of noise. Additionally, they are convolved with the detector point spread function and the energy distribution of the electron source. Often, iterative deconvolution is employed to sharpen peaks and improve the data. However, since the Richardson–Lucy algorithm (RLA) has become the standard deconvolution algorithm in EELS, little progress has been made in terms of technique. In this paper, the authors aim to provide an update to STEM-EELS deconvolution and demonstrate how to significantly improve results compared to those achievable with the RLA. The major limitation of the RLA is that it does not guarantee convergence. Furthermore, the RLA is restricted to pure Poisson noise and lacks adaptability due to limitations in its general structure, particularly when compared to more modern algorithms. A new and versatile approach is the Alternating Direction Method of Multipliers (ADMM), which is based on Lagrangian methods and enables to overcome these restrictions. The generality of ADMM allows us to develop a deconvolution algorithm tailored to EELS maps and incorporate a recent noise model. We extend the standard Bayesian maximum likelihood of the RLA to a maximum a-posteriori approach in ADMM, which enables us to leverage the principles of total general variation (TGV) to enforce convergence. Furthermore, we define the algorithm such that it operates unbiased of the user. To demonstrate the superiority of the ADMM, it is tested against the RLA using simulated data. Eventually, our algorithm is successfully applied to experimental data as well.
{"title":"An unbiased ADMM-TGV algorithm for the deconvolution of STEM-EELS maps","authors":"Christian Zietlow, Jörg K.N. Lindner","doi":"10.1016/j.ultramic.2025.114159","DOIUrl":"10.1016/j.ultramic.2025.114159","url":null,"abstract":"<div><div>Electron-energy-loss-spectroscopy (EELS) spectra in the scanning transmission electron microscope (STEM) are affected by various types of noise. Additionally, they are convolved with the detector point spread function and the energy distribution of the electron source. Often, iterative deconvolution is employed to sharpen peaks and improve the data. However, since the Richardson–Lucy algorithm (RLA) has become the standard deconvolution algorithm in EELS, little progress has been made in terms of technique. In this paper, the authors aim to provide an update to STEM-EELS deconvolution and demonstrate how to significantly improve results compared to those achievable with the RLA. The major limitation of the RLA is that it does not guarantee convergence. Furthermore, the RLA is restricted to pure Poisson noise and lacks adaptability due to limitations in its general structure, particularly when compared to more modern algorithms. A new and versatile approach is the Alternating Direction Method of Multipliers (ADMM), which is based on Lagrangian methods and enables to overcome these restrictions. The generality of ADMM allows us to develop a deconvolution algorithm tailored to EELS maps and incorporate a recent noise model. We extend the standard Bayesian maximum likelihood of the RLA to a maximum a-posteriori approach in ADMM, which enables us to leverage the principles of total general variation (TGV) to enforce convergence. Furthermore, we define the algorithm such that it operates unbiased of the user. To demonstrate the superiority of the ADMM, it is tested against the RLA using simulated data. Eventually, our algorithm is successfully applied to experimental data as well.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"275 ","pages":"Article 114159"},"PeriodicalIF":2.1,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144088772","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}
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