Ultramicroscopy最新文献_第2页

Theoretical study on the effect of temperature gradient on contact-free scanning for scanning ion conductance microscopy 关于温度梯度对扫描离子电导显微镜非接触扫描影响的理论研究

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-09-14 DOI: 10.1016/j.ultramic.2024.114054

{"title":"Theoretical study on the effect of temperature gradient on contact-free scanning for scanning ion conductance microscopy","authors":"","doi":"10.1016/j.ultramic.2024.114054","DOIUrl":"10.1016/j.ultramic.2024.114054","url":null,"abstract":"<div><p>Scanning ion-conductance microscopy (SICM) is a non-contact, high-resolution, and <em>in-situ</em> scanning probe microscope technique, it can be operated in probing the physical and chemical properties of biological samples such as living cells. Recently, using SICM to study the effects of microenvironment changes such as temperature changes on response of the biological samples has attracted significant attention. However, in this temperature gradient condition, one of the crucial but still unclear issues is the scanning feedback types and safe threshold. In this paper, a theoretical study of effect of the temperature gradient in electrolyte or sample surface on the SICM safe ion-current threshold is conducted using three-dimensional Poisson-Nernst-Planck, Navier-Stokes and energy equations. Two temperature gradient types, sample surface and two types of pipettes with different ratio of inner and outer radii are included, respectively. The results demonstrate that the local temperature of the electrolyte and then sample surface significantly affect the ion flow, shape of the approach curves and thus safe threshold in SICM pipette probe for contact-free scanning. There is a current-increased and decreased phases for approaching the surface with higher temperature and two current-decreased phases for surface with lower temperature. Based on this shape feature of approach curves, the change rate of current is analysis to illustrate the possibility for contact-free scanning of slope object. The results indicate that with the decrease of the normalized tip-surface distance, the coupling effect of large slope angle and local high temperature makes the increase in change rate of ion current not significant and then it challenging to realize contact-free scanning especially for higher surface temperature.</p></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142238089","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

Maximizing the notional area in single tip field emitters 最大化单尖端场发射器的名义面积

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-09-13 DOI: 10.1016/j.ultramic.2024.114049

引用次数: 0

Atomic resolution scanning transmission electron microscopy at liquid helium temperatures for quantum materials 液氦温度下用于量子材料的原子分辨率扫描透射电子显微镜

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-09-07 DOI: 10.1016/j.ultramic.2024.114039

{"title":"Atomic resolution scanning transmission electron microscopy at liquid helium temperatures for quantum materials","authors":"","doi":"10.1016/j.ultramic.2024.114039","DOIUrl":"10.1016/j.ultramic.2024.114039","url":null,"abstract":"<div><p>Fundamental quantum phenomena in condensed matter, ranging from correlated electron systems to quantum information processors, manifest their emergent characteristics and behaviors predominantly at low temperatures. This necessitates the use of liquid helium (LHe) cooling for experimental observation. Atomic resolution scanning transmission electron microscopy combined with LHe cooling (cryo-STEM) provides a powerful characterization technique to probe local atomic structural modulations and their coupling with charge, spin and orbital degrees-of-freedom in quantum materials. However, achieving atomic resolution in cryo-STEM is exceptionally challenging, primarily due to sample drifts arising from temperature changes and noises associated with LHe bubbling, turbulent gas flow, etc. In this work, we demonstrate atomic resolution cryo-STEM imaging at LHe temperatures using a commercial side-entry LHe cooling holder. Firstly, we examine STEM imaging performance as a function of He gas flow rate, identifying two primary noise sources: He-gas pulsing and He-gas bubbling. Secondly, we propose two strategies to achieve low noise conditions for atomic resolution STEM imaging: either by temporarily suppressing He gas flow rate using the needle valve or by acquiring images during the natural warming process. Lastly, we show the applications of image acquisition methods and image processing techniques in investigating structural phase transitions in Cr<sub>2</sub>Ge<sub>2</sub>Te<sub>6</sub>, CuIr<sub>2</sub>S<sub>4</sub>, and CrCl<sub>3</sub>. Our findings represent an advance in the field of atomic resolution electron microscopy imaging for quantum materials and devices at LHe temperatures, which can be applied to other commercial side-entry LHe cooling TEM holders.</p></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230370","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

Development of a liquid-helium free cryogenic sample holder with mK temperature control for autonomous electron microscopy. 开发用于自主电子显微镜的 mK 温度控制无液氦低温样品支架。

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-09-07 DOI: 10.1016/j.ultramic.2024.114037

X He, R Kostin, E Knight, M G Han, J Mun, I Bozovic, C Jing, Y Zhu

{"title":"Development of a liquid-helium free cryogenic sample holder with mK temperature control for autonomous electron microscopy.","authors":"X He, R Kostin, E Knight, M G Han, J Mun, I Bozovic, C Jing, Y Zhu","doi":"10.1016/j.ultramic.2024.114037","DOIUrl":"https://doi.org/10.1016/j.ultramic.2024.114037","url":null,"abstract":"<p><p>The automated and autonomous cryogenic transmission electron microscopy (Cryo-EM) demands a sample holder capable of maintaining temperatures below 10 K with precise control, long holding times, and minimal helium use. Rising to this challenge, we initiated an ambitious project to develop a novel closed-cycle cryocooler-based cryogenic sample holder that operates without the use of liquid helium and the consumption of gaseous helium. This article presents the design, construction, and experimental testing of the initial prototype, which achieves an ultimate temperature of 5.6 K with exceptional stability close to 1mK, while providing a wide temperature control range from 295 K to 5.6 K, marking a clear advancement in cryo-EM holder development. While the prototype was not designed for atomic resolution imaging and thus lacks a sturdy support system to mitigate mechanical vibrations from the cryocooler's pulsed tube, this innovative approach successfully demonstrates proof of concept. It offers unprecedented capabilities for state-of-the-art cryogenic microscopy and microanalysis in materials and biological sciences.</p>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142393722","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

Determination of five-parameter grain boundary characteristics in nanocrystalline Ni-W by scanning precession electron diffraction tomography 利用扫描前驱电子衍射层析技术测定纳米晶 Ni-W 中的五参数晶界特征

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-09-06 DOI: 10.1016/j.ultramic.2024.114038

{"title":"Determination of five-parameter grain boundary characteristics in nanocrystalline Ni-W by scanning precession electron diffraction tomography","authors":"","doi":"10.1016/j.ultramic.2024.114038","DOIUrl":"10.1016/j.ultramic.2024.114038","url":null,"abstract":"<div><p>Determining the full five-parameter grain boundary characteristics from experiments is essential for understanding grain boundaries impact on material properties, improving related models, and designing advanced alloys. However, achieving this is generally challenging, in particular at nanoscale, due to their 3D nature. In our study, we successfully determined the grain boundary characteristics of an annealed nickel-tungsten alloy (NiW) nanocrystalline needle-shaped specimen (tip) containing twins using Scanning Precession Electron Diffraction (SPED) Tomography. The presence of annealing twins in this face-centered cubic (fcc) material gives rise to common reflections in the SPED diffraction patterns, which challenges the reconstruction of orientation-specific virtual dark field (VDF) images required for tomographic reconstruction of the 3D grain shapes. To address this, an automated post-processing step identifies and deselects these shared reflections prior to the reconstruction of the VDF images. Combined with appropriate intensity normalization and projection alignment procedures, this approach enables high-fidelity 3D reconstruction of the individual grains contained in the needle-shaped sample volume. To probe the accuracy of the resulting boundary characteristics, the twin boundary surface normal directions were extracted from the 3D voxelated grain boundary map using a 3D Hough transform. For the sub-set of coherent Σ3 boundaries, the expected {111} grain boundary plane normals were obtained with an angular error of <3° for boundary sizes down to 400 nm². This work advances our ability to precisely characterize and understand the complex grain boundaries that govern material properties.</p></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0304399124001177/pdfft?md5=ee9e4301d297d24a4cc6093c9c64c35a&pid=1-s2.0-S0304399124001177-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230371","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

Clustering characteristic diffraction vectors in 4-D STEM data sets from overlapping structures in nanocrystalline and amorphous materials 从纳米晶体和非晶体材料的重叠结构中对 4-D STEM 数据集中的特征衍射矢量进行聚类

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-09-03 DOI: 10.1016/j.ultramic.2024.114040

{"title":"Clustering characteristic diffraction vectors in 4-D STEM data sets from overlapping structures in nanocrystalline and amorphous materials","authors":"","doi":"10.1016/j.ultramic.2024.114040","DOIUrl":"10.1016/j.ultramic.2024.114040","url":null,"abstract":"<div><p>We describe a method for identifying and clustering diffraction vectors in four-dimensional (4-D) scanning transmission electron microscopy data to determine characteristic diffraction patterns from overlapping structures in projection. First, the data is convolved with a 4-D kernel, then diffraction vectors are identified and clustered using both density-based clustering and a metric that emphasizes rotational symmetries. The method works well for both crystalline and amorphous samples and in high- and low-dose experiments. A simulated dataset of overlapping aluminum nanocrystals provides performance metrics as a function of Poisson noise and the number of overlapping structures. Experimental data from an aluminum nanocrystal sample shows similar performance. For an amorphous Pd<sub>77.5</sub>Cu<sub>6</sub>Si<sub>16.5</sub> thin film, experiments measuring glassy structure show strong evidence of 4- and 6-fold symmetry structures. A significant background arises from the diffraction of overlapping structures. Quantifying this background helps to separate contributions from single, rotationally symmetric structures vs. apparent symmetries arising from overlapping structures in projection.</p></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142230369","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

Differential phase contrast from electrons that cause inner shell ionization 引起内壳电离的电子产生的差分相位对比

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-08-26 DOI: 10.1016/j.ultramic.2024.114036

{"title":"Differential phase contrast from electrons that cause inner shell ionization","authors":"","doi":"10.1016/j.ultramic.2024.114036","DOIUrl":"10.1016/j.ultramic.2024.114036","url":null,"abstract":"<div><p>Differential Phase Contrast (DPC) imaging, in which deviations in the bright field beam are in proportion to the electric field, has been extensively studied in the context of pure elastic scattering. Here we discuss differential phase contrast formed from core-loss scattered electrons, i.e. those that have caused inner shell ionization of atoms in the specimen, using a transition potential approach for which we study the number of final states needed for a converged calculation. In the phase object approximation, we show formally that differential phase contrast formed from core-loss scattered electrons is mainly a result of preservation of elastic contrast. Through simulation we demonstrate that whether the inelastic DPC images show element selective contrast depends on the spatial range of the ionization interaction, and specifically that when the energy loss is low the delocalisation can lead to contributions to the contrast from atoms other than that ionized. We further show that inelastic DPC images remain robustly interpretable to larger thicknesses than is the case for elastic DPC images, owing to the incoherence of the inelastic wavefields, though subtleties due to channelling remain. Lastly, we show that while a very high dose will be needed for sufficient counting statistics to discern differential phase contrast from core-loss scattered electrons, there is some enhancement of the signal-to-noise ratio with thickness that makes inelastic DPC imaging more achievable for thicker samples.</p></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0304399124001153/pdfft?md5=ffc4ecab832fb6a095cc846efe6efee1&pid=1-s2.0-S0304399124001153-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142088295","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

Differential phase contrast STEM image calculation software – Magnifier 差分相衬 STEM 图像计算软件 - 放大镜

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-08-22 DOI: 10.1016/j.ultramic.2024.114035

引用次数: 0

The impact of electric field strength on the accuracy of boron dopant quantification in silicon using atom probe tomography 电场强度对利用原子探针层析成像技术量化硅中硼掺杂物精度的影响

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-08-21 DOI: 10.1016/j.ultramic.2024.114034

{"title":"The impact of electric field strength on the accuracy of boron dopant quantification in silicon using atom probe tomography","authors":"","doi":"10.1016/j.ultramic.2024.114034","DOIUrl":"10.1016/j.ultramic.2024.114034","url":null,"abstract":"<div><p>This study investigates the impact of the surface electric field on the quantification accuracy of boron (B) implanted silicon (Si) using atom probe tomography (APT). The Si Charge-State Ratio (CSR(Si) = Si<sup>2+</sup>/Si<sup>+</sup>) was used as an indirect measure of the average apex electric field during analysis. For a range of electric fields, the accuracy of the total implanted dose and the depth profile shape determined by APT was evaluated against the National Institute of Standards and Technology Standard Reference Material 2137. The radial (non-)uniformity of the detected B was also examined. At a higher surface electric field (i.e., a greater CSR(Si)), the determined B dose converges on the certified dose. Additionally, the depth profile shape tends towards that derived by secondary ion mass spectrometry. This improvement coincides with a more uniform radial B distribution, evidenced by desorption maps. In contrast, for lower surface electric fields (i.e., a lower CSR(Si)), the B dose is significantly underestimated, and the depth profile is artificially stretched. The desorption maps also indicate a highly inhomogeneous B emission localized around the center of the detector, which is believed to be an artifact of B surface migration on the tip of the sample. For the purposes of routine investigations of semiconductor devices using APT, these results illustrate the potential origin of quantification artifacts and their severity at different operating conditions, thus providing pathways towards best practices for accurate and repeatable measurements.</p></div>","PeriodicalId":23439,"journal":{"name":"Ultramicroscopy","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142084316","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

Design of electrostatic lenses through genetic algorithm and particle swarm optimisation methods integrated with differential algebra 通过与微分代数相结合的遗传算法和粒子群优化方法设计静电透镜

IF 2.1 3区工程技术

Ultramicroscopy Pub Date : 2024-08-15 DOI: 10.1016/j.ultramic.2024.114024

引用次数: 0