Ultramicroscopy最新文献

{"title":"Approaching one nanosecond temporal resolution with square-wave-based control signals for interference gating","authors":"Simon Gaebel ,&nbsp;Hüseyin Çelik ,&nbsp;Dirk Berger ,&nbsp;Christoph T. Koch ,&nbsp;Michael Lehmann ,&nbsp;Tolga Wagner","doi":"10.1016/j.ultramic.2025.114208","DOIUrl":"10.1016/j.ultramic.2025.114208","url":null,"abstract":"<div><div>Interference gating (iGate) has emerged as a valuable and instrumentally easy-to-implement technique for time-resolved electron holography, allowing the study of dynamic processes on the nanosecond scale. Traditionally, iGate has relied on noise-based control signals, which, while effective, present challenges in achieving high repetition rates due to the complexity of signal generation and transmission. In this work, a square-wave-based control signal for iGate is introduced, offering a simpler and more robust alternative. Experimental validation indicates that this approach maintains comparable performance to the noise-based signal while enabling an order-of-magnitude improvement in temporal resolution, reaching <span><math><mrow><mtext>1.9</mtext><mspace></mspace><mtext>ns</mtext></mrow></math></span> with our current instrumentation. This advancement holds promise for improved time-resolved investigations of ultrafast nanoscale phenomena in TEM, providing a low barrier to entry.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114208"},"PeriodicalIF":2.1,"publicationDate":"2025-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144679807","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}

{"title":"Preface to the Proceedings of the Thirteenth International Workshop on Low Energy Electron Microscopy and Photoemission Electron Microscopy (LEEM/PEEM 13).","authors":"Karen L Kavanagh","doi":"10.1016/j.ultramic.2025.114209","DOIUrl":"https://doi.org/10.1016/j.ultramic.2025.114209","url":null,"abstract":"","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":" ","pages":"114209"},"PeriodicalIF":2.1,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144699612","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}

{"title":"Large-angle convergent-beam electron diffraction patterns via conditional generative adversarial networks","authors":"Joseph J. Webb ,&nbsp;Richard Beanland ,&nbsp;Rudolf A. Römer","doi":"10.1016/j.ultramic.2025.114198","DOIUrl":"10.1016/j.ultramic.2025.114198","url":null,"abstract":"<div><div>We show how generative machine learning can be used for the rapid computation of strongly dynamical electron diffraction directly from crystal structures, specifically in large-angle convergent-beam electron diffraction (LACBED) patterns. We find that a conditional generative adversarial network can learn the connection between the projected potential from a cubic crystal’s unit cell and the corresponding LACBED pattern. Our model can generate diffraction patterns on a GPU many orders of magnitude faster than existing direct simulation methods. Furthermore, our approach can accurately retrieve the projected potential from diffraction patterns, opening a new approach for the inverse problem of determining crystal structure.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114198"},"PeriodicalIF":2.1,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144694461","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}

{"title":"Cryogenic sample preparation: Comparative analysis of Ga+ and Xe+ FIB milling for TEM and APT examination of zirconium","authors":"Ömer Koç ,&nbsp;Benjamin M. Jenkins ,&nbsp;Jack Haley ,&nbsp;Christina Hofer ,&nbsp;Martin S. Meier ,&nbsp;Megan E. Jones ,&nbsp;Robert W. Harrison ,&nbsp;Michael Preuss ,&nbsp;Michael P. Moody ,&nbsp;Christopher R.M. Grovenor ,&nbsp;Philipp Frankel","doi":"10.1016/j.ultramic.2025.114210","DOIUrl":"10.1016/j.ultramic.2025.114210","url":null,"abstract":"<div><div>Specimen preparation is a key step in the characterisation of materials systems. For high-resolution characterisation techniques such as transmission electron microscopy (TEM) and atom probe tomography (APT), it is necessary to have a sample preparation method that creates the nano-scale samples required for analysis but does not significantly modify the initial microstructure.</div><div>The preparation of hexagonal close-packed materials by focussed ion beam milling (FIB) and electropolishing has previously been shown to be complicated by hydride formation. The formation of hydrides can be reduced by the application of cryogenic temperatures during the final stages of Ga⁺ ion FIB milling, which are often conducted at low accelerating voltages in order to minimise irradiation-induced damage.</div><div>Xe⁺ ion plasma FIBs are now commonly used in the preparation of samples due to their higher milling rates. However, the severity of the hydride formation in hexagonal close-packed materials during Xe⁺ ion milling is unclear. In this paper, we compare Xe⁺ and Ga⁺ FIB milling to prepare Zr samples at ambient and cryogenic temperatures. By studying TEM and APT samples, we are able to compare the levels of hydride formation after FIB preparation caused by the different preparation techniques. APT is used to estimate the levels of hydrogen in the samples. These results represent an important contribution to researchers who use FIB preparation to create TEM and APT specimens from hexagonal close-packed metals such as zirconium.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114210"},"PeriodicalIF":2.1,"publicationDate":"2025-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144665697","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}

{"title":"Removing constraints of 4D-STEM with a framework for event-driven acquisition and processing","authors":"Arno Annys,&nbsp;Hoelen L. Lalandec Robert,&nbsp;Saleh Gholam,&nbsp;Joke Hadermann,&nbsp;Jo Verbeeck","doi":"10.1016/j.ultramic.2025.114206","DOIUrl":"10.1016/j.ultramic.2025.114206","url":null,"abstract":"<div><div>Pixelated detectors in scanning transmission electron microscopy (STEM) generate large volumes of data, often tens to hundreds of GB per scan. However, to make current advancements scalable and enable widespread adoption, it is essential to use the most efficient representation of an electron’s information. Event-driven direct electron detectors, such as those based on the Timepix3 chip, offer significant potential for electron microscopy, particularly for low-dose experiments and real-time data processing. In this study, we compare sparse and dense data representations in terms of their size and computational requirements across various 4D-STEM scenarios, including high-resolution imaging and nano-beam electron diffraction. The advantages of performing 4D-STEM in an event-driven mode – such as reduced requirements in memory, bandwidth, and computational demands – can only be fully leveraged if the entire acquisition and processing pipeline is optimized to work directly with the event format, avoiding intermediate dense representations. We introduce a framework designed for acquisition and processing based on this event format, and demonstrate live processing of event-driven 4D-STEM, including analytical ptychography.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114206"},"PeriodicalIF":2.1,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144632753","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}

{"title":"Orientation-adaptive virtual imaging of defects using EBSD","authors":"Nicolò M. della Ventura ,&nbsp;James D. Lamb ,&nbsp;William C. Lenthe ,&nbsp;McLean P. Echlin ,&nbsp;Julia T. Pürstl ,&nbsp;Emily S. Trageser ,&nbsp;Alejandro M. Quevedo ,&nbsp;Matthew R. Begley ,&nbsp;Tresa M. Pollock ,&nbsp;Daniel S. Gianola ,&nbsp;Marc De Graef","doi":"10.1016/j.ultramic.2025.114205","DOIUrl":"10.1016/j.ultramic.2025.114205","url":null,"abstract":"<div><div>Electron backscatter diffraction (EBSD) is a foundational technique for characterizing crystallographic orientation, phase distribution, and lattice strain. Embedded within EBSD patterns lies latent information on dislocation structures, subtly encoded due to their deviation from perfect crystallinity — a feature often underutilized. Here, a novel framework termed orientation-adaptive virtual apertures (OAVA) is introduced. OAVAs enable the generation of virtual images tied to specific diffraction conditions, allowing the direct visualization of individual dislocations from a single EBSD map. By dynamically aligning virtual apertures in reciprocal space with the local crystallographic orientation, the method enhances contrast from defect-related strain fields, mirroring the principles of diffraction-contrast imaging in TEM, but without sample tilting. The approach capitalizes on the extensive diffraction space captured in a single high-quality EBSD scan, with its effectiveness enhanced by modern direct electron detectors that offer high-sensitivity at low accelerating voltages, reducing interaction volume and improving spatial resolution. We demonstrate that using OAVAs, identical imaging conditions can be applied across a polycrystalline field-of-view, enabling uniform contrast in differently oriented grains. Furthermore, in single-crystal GaN, threading dislocations are consistently resolved. Algorithms for the automated detection of dislocation-induced contrast are presented, advancing defect characterization. By using OAVAs across a wide range of diffraction conditions in GaN, the visibility/invisibility of defects, owing to the anisotropy of the elastic strain field, is assessed and linked to candidate Burgers vectors. Altogether, OAVA offers a new and high-throughput pathway for orientation-specific defect characterization with the potential for automated, large-area defect analysis in single and polycrystalline materials.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114205"},"PeriodicalIF":2.1,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597063","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}

{"title":"Towards continuous time-dependent tomography: implementation and evaluation of continuous acquisition schemes in electron tomography","authors":"Timothy M. Craig ,&nbsp;Robin Girod ,&nbsp;Gail Vinnacombe-Willson ,&nbsp;Luis M. Liz-Marzán ,&nbsp;Sara Bals","doi":"10.1016/j.ultramic.2025.114207","DOIUrl":"10.1016/j.ultramic.2025.114207","url":null,"abstract":"<div><div>Electron tomography is a microscopy technique that allows the three-dimensional (3D) characterization of nanomaterials by reconstructing a 3D volume from a series of two-dimensional (2D) projection images acquired at different viewing angles. In a transmission electron microscope (TEM), the change in angle is achieved by tilting the sample holder and conventionally follows an incremental tilt scheme. Images are typically acquired between <span><math><mo>±</mo></math></span> 60–80°, as dictated by the TEM geometry, and in small, 2–3°, increments to minimize sample shifts and facilitate acquisition and post-processing. This tilt scheme unfortunately performs poorly when time resolution is necessary, i.e., when as many 3D reconstructions as possible of the same object within a given time are desired. Golden ratio scanning (GRS) and binary decomposition (BD) have been proposed in other tomographies because they allow consecutive reconstructions to share some projections. However, due to practical considerations, they have seen limited usage in electron tomography. In this work, we present optimized implementations of GRS and BD for electron tomography with corrections for alignment, backlash, and angular uniformity. These tilt schemes were compared with incremental acquisition for simulated and experimental datasets in static or dynamic contexts. Experimentally, GRS and BD required 2–3 times longer acquisition time, and resulted in a 2 times increase in electron dose compared to the incremental scheme, thus confirming the incremental scheme as the method to be favored for static applications. In dynamic applications, our results suggest that a time vs. spatial resolution tradeoff should be considered. Nonetheless, GRS and BD schemes would achieve up to 30x higher 3D frame rate, showing promise toward time-dependent electron tomography.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114207"},"PeriodicalIF":2.1,"publicationDate":"2025-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144655327","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}

{"title":"High-energy resolution monochromated STEM-EELS mapping across large areas","authors":"Caleb Whittier ,&nbsp;Nabil D. Bassim","doi":"10.1016/j.ultramic.2025.114202","DOIUrl":"10.1016/j.ultramic.2025.114202","url":null,"abstract":"<div><div>Scanning transmission electron microscopy (STEM) allows for high spatial-resolution analysis of materials and, when coupled with electron energy loss spectroscopy (EELS), becomes capable of providing substantial insight into both chemical and optical properties. In recent years, focus has moved towards understanding material properties at the atomic level using EELS. However, there are still significant barriers when attempting to perform high-energy resolution monochromated STEM-EELS analysis on large structures. Off-axis distortions cause additional aberrations to couple into the spectrometer when scanning across large regions. This often limits STEM-EELS mapping to small areas to maintain the energy resolution or requires sacrificing this resolution to spectrum maps spanning multiple microns. We propose here a methodology enabling low-loss STEM-EELS spectrum mapping to be performed over tens to hundreds of microns while maintaining high energy-resolution through modification of the EELS collection conditions. This is accomplished not only through careful alignment of the scan/descan coils, but, more importantly, through implementation of elongated camera lengths that effectively magnify the object over the EELS entrance aperture, cutting out higher order aberrations and reducing shifts on the spectrometer.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114202"},"PeriodicalIF":2.1,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144597064","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}

{"title":"Data-efficient 4D-STEM in SEM: Beyond 2D materials to metallic materials","authors":"Ujjval Bansal ,&nbsp;Amit Sharma ,&nbsp;Barbara Putz ,&nbsp;Christoph Kirchlechner ,&nbsp;Subin Lee","doi":"10.1016/j.ultramic.2025.114203","DOIUrl":"10.1016/j.ultramic.2025.114203","url":null,"abstract":"<div><div>Four-dimensional scanning transmission electron microscopy (4D-STEM) is a powerful tool that allows for the simultaneous acquisition of spatial and diffraction information, driven by recent advancements in direct electron detector technology. Although 4D-STEM has been predominantly developed for and used in conventional TEM and STEM, efforts are being made to implement the technique in scanning electron microscopy (SEM). In this paper, we push the boundaries of 4D-STEM in SEM and extend its capabilities in three key aspects: (1) faster acquisition rate with reduced data size, (2) higher angular resolution, and (3) application to various materials including conventional alloys and focused ion beam (FIB) lamella. Specifically, operating the MiniPIX Timepix3 detector in the event-driven mode significantly improves the acquisition rate by a factor of a few tenths compared to conventional frame-based mode, thereby opening up possibilities for integrating 4D-STEM into various <em>in situ</em> SEM testing. Furthermore, with a novel stage-detector geometry, a camera length of 160 mm is achieved which improves the angular resolution amplifying its utility, for example, magnetic or electric field imaging. Lastly, we successfully imaged a nanostructured platinum-copper thin film with a grain size of 16 nm and a thickness of 20 nm, and identified annealing twins in FIB-prepared polycrystalline copper using virtual dark-field imaging and orientation mapping. This work demonstrates the potential of synergetic combination of 4D-STEM with <em>in situ</em> experiments, and broadening its applications across a wide range of materials.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"276 ","pages":"Article 114203"},"PeriodicalIF":2.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580153","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}

{"title":"Cryogen-free low-temperature photoemission electron microscopy for high-resolution nondestructive imaging of electronic phases","authors":"Chen Wang ,&nbsp;Shaoshan Wang ,&nbsp;Chuan Guo ,&nbsp;Chengjian Yu ,&nbsp;Qi Fu ,&nbsp;Xiaopeng Xie ,&nbsp;Changxi Zheng","doi":"10.1016/j.ultramic.2025.114204","DOIUrl":"10.1016/j.ultramic.2025.114204","url":null,"abstract":"<div><div>Quantum materials exhibit phases such as superconductivity at low temperatures, yet imaging their phase transition dynamics with high spatial resolution remains challenging due to conventional tools' limitations—scanning tunneling microscopy offers static snapshots, while transmission electron microscopy lacks band sensitivity. Photoemission electron microscopy (PEEM) can resolve band structures in real/reciprocal spaces rapidly, but suffering from insufficient resolution for (near)atomic-scale quantum physics due to the unstable cooling designs. Here, we developed cryogen-free low-temperature PEEM (CFLT-PEEM) achieving 21.1 K stably. CFLT-PEEM attains a record-breaking resolution of 4.48 nm without aberration correction, enabling direct visualization of surface-state distribution characteristics along individual atomic steps. The advancement lies in narrowing the segment of band structures for imaging down to 160 meV, which minimizes the chromatic aberration of PEEM. CFLT-PEEM enables rapid, nondestructive high-resolution imaging of cryogenic electronic structures, positioning it as a powerful tool for physics and beyond.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"277 ","pages":"Article 114204"},"PeriodicalIF":2.1,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144614592","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}