Ultramicroscopy最新文献_第4页

Relativistic EELS scattering cross-sections for microanalysis based on Dirac solutions 基于Dirac解的相对论EELS微分析散射截面。

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-12-02 DOI: 10.1016/j.ultramic.2024.114083

Zezhong Zhang , Ivan Lobato , Hamish Brown , Dirk Lamoen , Daen Jannis , Johan Verbeeck , Sandra Van Aert , Peter D. Nellist

{"title":"Relativistic EELS scattering cross-sections for microanalysis based on Dirac solutions","authors":"Zezhong Zhang , Ivan Lobato , Hamish Brown , Dirk Lamoen , Daen Jannis , Johan Verbeeck , Sandra Van Aert , Peter D. Nellist","doi":"10.1016/j.ultramic.2024.114083","DOIUrl":"10.1016/j.ultramic.2024.114083","url":null,"abstract":"<div><div>The rich information of electron energy-loss spectroscopy (EELS) comes from the complex inelastic scattering process whereby fast electrons transfer energy and momentum to atoms, exciting bound electrons from their ground states to higher unoccupied states. To quantify EELS, the common practice is to compare the cross-sections integrated within an energy window or fit the observed spectrum with theoretical differential cross-sections calculated from a generalized oscillator strength (GOS) database with experimental parameters. The previous Hartree–Fock-based and DFT-based GOS are calculated from Schrödinger’s solution of atomic orbitals, which does not include the full relativistic effects. Here, we attempt to go beyond the limitations of the Schrödinger solution in the GOS tabulation by including the full relativistic effects using the Dirac equation within the local density approximation, which is particularly important for core–shell electrons of heavy elements with strong spin–orbit coupling. This has been done for all elements in the periodic table (up to Z = 118) for all possible excitation edges using modern computing capabilities and parallelization algorithms. The relativistic effects of fast incoming electrons were included to calculate cross-sections that are specific to the acceleration voltage. We make these tabulated GOS available under an open-source license to the benefit of both academic users and to allow integration into commercial solutions.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"269 ","pages":"Article 114083"},"PeriodicalIF":2.1,"publicationDate":"2024-12-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142792288","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}

引用次数: 0

Aberration calculation of microlens array using differential algebraic method 微透镜阵列像差的微分代数计算。

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-11-30 DOI: 10.1016/j.ultramic.2024.114085

Jintao Hu, Lei Yue, Yihao Ma, Fu Liu, Yongfeng Kang

{"title":"Aberration calculation of microlens array using differential algebraic method","authors":"Jintao Hu, Lei Yue, Yihao Ma, Fu Liu, Yongfeng Kang","doi":"10.1016/j.ultramic.2024.114085","DOIUrl":"10.1016/j.ultramic.2024.114085","url":null,"abstract":"<div><div>Microlens array (MLA), through which all the sub-beams are focused, is widely used in multi-electron-beam systems. In this work, based on the differential algebraic (DA) method, we propose an approach in calculating the high-order aberrations for both axial and off-axial microlenses, considering the multipole fields that are introduced by the neighborhood structures in MLA, as well as the rotationally symmetric field. To perform the DA calculation, the electric fields of the microlenses are analyzed by using the azimuthal Fourier analysis and the Fourier-Bessel series Expansion. The resulting field components, including both rotationally symmetric field and the multipole fields, are transferred into DA arguments and operated as per DA methodology. Then, by developing and employing the DA theory and algorithm, the primary and high-order aberrations are calculated and obtained simultaneously for both the axial and off-axial microlenses by tracing only one reference ray. Finally, we calculate, analyze and discuss the primary and high-order aberrations of two example MLAs, for both axial and off-axial microlenses. The effects of the dodecapole fields on the aberrations are also analyzed.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"269 ","pages":"Article 114085"},"PeriodicalIF":2.1,"publicationDate":"2024-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142792283","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}

引用次数: 0

Effect of the surrounding environment on electron beam irradiation damage of enhanced green fluorescent protein 周围环境对电子束辐照增强绿色荧光蛋白损伤的影响

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-11-25 DOI: 10.1016/j.ultramic.2024.114082

Haruyoshi Osakabe , Mihiro Suzuki , Toshiki Shimizu , Hiroki Minoda

{"title":"Effect of the surrounding environment on electron beam irradiation damage of enhanced green fluorescent protein","authors":"Haruyoshi Osakabe , Mihiro Suzuki , Toshiki Shimizu , Hiroki Minoda","doi":"10.1016/j.ultramic.2024.114082","DOIUrl":"10.1016/j.ultramic.2024.114082","url":null,"abstract":"<div><div>Fluorescent proteins exhibit fluorescence and photoconversion, which are used to study biological phenomena. Among these, enhanced green fluorescent protein (EGFP) emits cathodoluminescence when irradiated with electron beams; this phenomenon has numerous applications in new research tools for biological phenomena. However, bleaching during electron irradiation is a major problem. Generally, the presence of water is important for biological samples, and structural observations are often performed under cryogenic conditions. One of the advantages of cryogenic conditions is the stabilization of the sample due to cooling. However, it is unclear which factor is more effective: the presence of water molecules or cryogenic preservation. To explore the stabilizing factors of the sample structure, we prepared four environments around the sample–dry at room temperature, wet at room temperature, dry at low temperature, and under cryogenic conditions–and investigated the electron beam irradiation damage by measuring the fluorescence emission spectra. Emission intensity from EGFP was attenuated, and the peak was red-shifted by electron beam irradiation; however, the intensity attenuation was fast under dry conditions at low temperature and slow under wet conditions at room temperature. These results imply that sample cooling has no significant effect on the stability of the EGFP chromophore and that the presence of water molecules is extremely important.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"268 ","pages":"Article 114082"},"PeriodicalIF":2.1,"publicationDate":"2024-11-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142746083","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}

引用次数: 0

Direct electron detection for EBSD of low symmetry & beam sensitive ceramics 用于低对称性和光束敏感陶瓷 EBSD 的直接电子探测

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-11-23 DOI: 10.1016/j.ultramic.2024.114079

Nicolò M. Della Ventura , Andrew R. Ericks , McLean P. Echlin , Kalani Moore , Tresa M. Pollock , Matthew R. Begley , Frank W. Zok , Marc De Graef , Daniel S. Gianola

{"title":"Direct electron detection for EBSD of low symmetry & beam sensitive ceramics","authors":"Nicolò M. Della Ventura , Andrew R. Ericks , McLean P. Echlin , Kalani Moore , Tresa M. Pollock , Matthew R. Begley , Frank W. Zok , Marc De Graef , Daniel S. Gianola","doi":"10.1016/j.ultramic.2024.114079","DOIUrl":"10.1016/j.ultramic.2024.114079","url":null,"abstract":"<div><div>Electron backscatter diffraction (EBSD) is a powerful tool for determining the orientations of near-surface grains in engineering materials. However, many ceramics present challenges for routine EBSD data collection and indexing due to small grain sizes, high crack densities, beam and charge sensitivities, low crystal symmetries, and pseudo-symmetric pattern variants. Micro-cracked monoclinic hafnia, tetragonal hafnon, and hafnia/hafnon composites exhibit all such features, and are used in the present work to show the efficacy of a novel workflow based on a direct detecting EBSD sensor and a state-of-the-art pattern indexing approach. At 5 and 10 keV primary beam energies (where beam-induced damage and surface charge accumulation are minimal), the direct electron detector produces superior diffraction patterns with 10x lower doses compared to a phosphor-coupled indirect detector. Further, pseudo-symmetric variant-related indexing errors from a Hough-based approach (which account for at least 4%-14% of map areas) are easily resolved by dictionary indexing. In short, the workflow unlocks fundamentally new opportunities to characterize materials historically unsuited for EBSD.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"268 ","pages":"Article 114079"},"PeriodicalIF":2.1,"publicationDate":"2024-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721238","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}

引用次数: 0

Chinese knot inspired isotropic linear scanning method for improved imaging performance in AFM 受中国结启发的各向同性线性扫描方法可提高原子力显微镜的成像性能

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-11-18 DOI: 10.1016/j.ultramic.2024.114081

Xiaolong Jia , Haitao Wu , Qubo Jiang , Qilin Zeng , Wentao Zhang , Yanding Qin

{"title":"Chinese knot inspired isotropic linear scanning method for improved imaging performance in AFM","authors":"Xiaolong Jia , Haitao Wu , Qubo Jiang , Qilin Zeng , Wentao Zhang , Yanding Qin","doi":"10.1016/j.ultramic.2024.114081","DOIUrl":"10.1016/j.ultramic.2024.114081","url":null,"abstract":"<div><div>Atomic force microscope (AFM) is an important nano-scale surface characterization and measurement method. Raster scanning method (RSM), widely used in AFMs, faces limitations on scanning speed and imaging accuracy. In this paper, an isotropic linear scanning method (ILSM) is proposed to improve the AFM imaging performance. Inspired by Chinese knot, ILSM is constructed by integrating two iterative triangular scanning trajectories in X and Y axes, similar to triangular Lissajous. Compared with the other scanning methods, ILSM features isotropic scanning trajectory across the scanning region. It is also easy to increase either the scanning speed or scanning resolution using ILSM. Subsequently, to address the hysteresis associated with the piezoelectric actuator, a new tracking algorithm is proposed by combining adaptive Kalman filtering and direct inverse modeling approach. Finally, AFM imaging experiments are conducted to validate the effectiveness of the proposed method. It can be found that the artifacts in RSM can be efficiently eliminated using the proposed method, thus improving the imaging quality.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"268 ","pages":"Article 114081"},"PeriodicalIF":2.1,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142699969","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}

引用次数: 0

Toward quantitative thermoelectric characterization of (nano)materials by in-situ transmission electron microscopy 利用原位透射电子显微镜对（纳米）材料进行定量热电表征。

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-11-06 DOI: 10.1016/j.ultramic.2024.114071

Simon Hettler , Mohammad Furqan , Andrés Sotelo , Raul Arenal

{"title":"Toward quantitative thermoelectric characterization of (nano)materials by in-situ transmission electron microscopy","authors":"Simon Hettler , Mohammad Furqan , Andrés Sotelo , Raul Arenal","doi":"10.1016/j.ultramic.2024.114071","DOIUrl":"10.1016/j.ultramic.2024.114071","url":null,"abstract":"<div><div>We explore the possibility to perform an <em>in-situ</em> transmission electron microscopy (TEM) thermoelectric characterization of materials. A differential heating element on a custom <em>in-situ</em> TEM microchip allows to generate a temperature gradient across the studied materials, which are simultaneously measured electrically. A thermovoltage was induced in all studied devices, whose sign corresponds to the sign of the Seebeck coefficient of the tested materials. The results indicate that <em>in-situ</em> thermoelectric TEM studies can help to profoundly understand fundamental aspects of thermoelectricity, which is exemplary demonstrated by tracking the thermovoltage during <em>in-situ</em> crystallization of an amorphous Ge thin film. We propose an improved <em>in-situ</em> TEM microchip design, which should facilitate a full quantitative measurement of the induced temperature gradient, the electrical and thermal conductivities, as well as the Seebeck coefficient. The benefit of the <em>in-situ</em> approach is the possibility to directly correlate the thermoelectric properties with the structure and chemical composition of the entire studied device down to the atomic level, including grain boundaries, dopants or crystal defects, and to trace its dynamic evolution upon heating or during the application of electrical currents.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"268 ","pages":"Article 114071"},"PeriodicalIF":2.1,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142629442","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}

引用次数: 0

New experimental methodology for determining the second crossover energy in insulators under stationary e-irradiation in a SEM 在扫描电子显微镜中确定静态电子辐照下绝缘体第二交叉能的新实验方法。

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-11-01 DOI: 10.1016/j.ultramic.2024.114069

H. Hammami, S. Fakhfakh

引用次数: 0

Beyond the random phase approximation (RPA): First principles calculation of the valence EELS spectrum for KBr including local field, quasiparticle, excitonic and spin orbit coupling effects 超越随机相近似 (RPA)：KBr 价电子能谱的第一性原理计算，包括局部场、准粒子、激子和自旋轨道耦合效应。

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-10-30 DOI: 10.1016/j.ultramic.2024.114070

V.J. Keast

引用次数: 0

A high-performance reconstruction method for partially coherent ptychography 部分相干层析成像的高性能重建方法

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-10-28 DOI: 10.1016/j.ultramic.2024.114068

Wenhui Xu , Shoucong Ning , Pengju Sheng , Huixiang Lin , Angus I Kirkland , Yong Peng , Fucai Zhang

{"title":"A high-performance reconstruction method for partially coherent ptychography","authors":"Wenhui Xu , Shoucong Ning , Pengju Sheng , Huixiang Lin , Angus I Kirkland , Yong Peng , Fucai Zhang","doi":"10.1016/j.ultramic.2024.114068","DOIUrl":"10.1016/j.ultramic.2024.114068","url":null,"abstract":"<div><div>Ptychography is now integrated as a tool in mainstream microscopy allowing quantitative and high-resolution imaging capabilities over a wide field of view. However, its ultimate performance is inevitably limited by the available coherent flux when implemented using electrons or laboratory X-ray sources. We present a universal reconstruction algorithm with high tolerance to low coherence for both far-field and near-field ptychography. The approach is practical for partial temporal and spatial coherence and requires no <em>prior</em> knowledge of the source properties. Our initial visible-light and electron data show that the method can dramatically improve the reconstruction quality and accelerate the convergence rate of the reconstruction. The approach also integrates well into existing ptychographic engines. It can also improve mixed-state and numerical monochromatisation methods, requiring a smaller number of coherent modes or lower dimensionality of Krylov subspace while providing more stable and faster convergence. We propose that this approach could have significant impact on ptychography of weakly scattering samples.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"267 ","pages":"Article 114068"},"PeriodicalIF":2.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554993","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}

引用次数: 0

A simple circularity-based approach for nanoparticle size histograms beyond the spherical approximation 超越球面近似的基于圆度的纳米粒子尺寸直方图简单方法。

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-10-28 DOI: 10.1016/j.ultramic.2024.114067

Florent Tournus

{"title":"A simple circularity-based approach for nanoparticle size histograms beyond the spherical approximation","authors":"Florent Tournus","doi":"10.1016/j.ultramic.2024.114067","DOIUrl":"10.1016/j.ultramic.2024.114067","url":null,"abstract":"<div><div>Conventional Transmission Electron Microscopy (TEM) is widely used for routine characterization of the size and shape of an assembly of (nano)particles. While the most basic approach only uses the projected area of each particle to infer its size (the “circular equivalent diameter” corresponding to the so-called “spherical approximation”), other shape descriptors can be determined and used for more elaborate analyses. In this article we present a generic model of particles, considered to be made of a few individual grains, and show how the equivalent size (i.e. a particle volume information) can be reliably deduced using only two basic parameters: the projected area and the perimeter of a particle. We compare this simple model to the spherical and ellipsoidal approximations and discuss its benefits. Then, partial coalescence of grains in a particle is also considered and we show how a simple analytical approximation, based on the circularity parameter of each particle, can improve the experimental determination of a particle size histogram. The analysis of experimental observations on nanoparticles assemblies obtained by mass-selected cluster deposition is presented, to illustrate the efficiency of the proposed approach for the determination of particle size just from conventional TEM images. We show how the presence of multimers offers an excellent opportunity to validate our improved and simple procedure. In addition, since the circularity plays a central role in this approach, attention is attracted on the perimeter determination in a pixelated image.</div></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":"268 ","pages":"Article 114067"},"PeriodicalIF":2.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142606606","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}

引用次数: 0