冷冻电镜技术——2017年诺贝尔化学奖介绍

介绍了2017年诺贝尔化学奖的3位获得者在冷冻电镜领域的主要贡献，同时介绍了冷冻电镜技术的用途、一般工作流程和其局限性，以及中国学者在冷冻电镜技术应用研究中的贡献。     

电子显微镜下的纳米世界

以高中阶段知识为基础,简述了扫描电子显微镜、透射电子显微镜等电镜技术的发展和基本原理,并以实际应用案例介绍了电镜技术在纳米科学领域的应用,最后给出了电镜技术的未来发展前景。     

低反差样品电镜图像衬度的提高

介绍了低反差生物医学样品在其制备，电镜观察以及底片和片的冲洗过程中提高电镜图像衬度的方法。     

冯晖墓壁画颜料的高分辨电镜和拉曼光谱分析

利用高分辨率电镜(HREM)和拉曼光谱等方法,对五代冯晖墓内壁画不同颜料的结构与成分进行了分析。结果表明,红色、黄色、黑色等矿物颜料保存都较为完好,未发生显著的变化,这为以后壁画保护方案的确立提供了科学依据、同时也证明,在样品量极少的情况下,利用高分辨电镜和拉曼光谱等方法可有效鉴别古代无机颜料的种类。     

JSM-5610LV扫描电镜的日常维护及常见故障排除

在扫描电子显微镜的日常维护管理中,应当控制好室内环境因素,保持电镜内部长期处高真空状态,定期检查其附属设备是否达到要求,介绍电镜经常出现的死机、黑屏显示图像不正常等故障的排除方法。     

一种简易扩散泵封闭式加热器

介绍了一种用电镜扩散泵的封闭式加热器。它具有结构简单，安装及检修方便，成本低廉等特点，该装置适用于ＪＥＭ－２００ＣＸ电镜及ＪＥＥ－４Ｘ真空喷镀仪配置，近年来的使用证明该装置完全可以替代原装进口封闭式加热器。     

电镜油箱绝缘油变质的处理

高压油箱是电子显微镜(以下简称电镜)的关键性部件。它的工作正常与否会直接影响电镜的性能和使用。由于它是处于高电压的工作状态,技术条件很严格。如果油箱绝缘油老化变质或被污染而使其性能破坏时,应当如何处理呢?现介绍如下方法供参考。     

中南五省区第五届电镜技术交流会在桂林召开

今年7月6日至10日中南地区五省区102个科研所、大专院校、厂矿等单位130多名代表在桂林举行电镜技术交流会。中南电镜技术交流会每两年举行一次,本次是第五届,由广西科委大型仪管办和广西电镜学会筹办。会议上中国电镜学会理事张立人付教授作了《生物大分子与电镜技术研究的进展》报告;曹书云付教授作了《国外电镜发展概况》、叶恒强付研     

JEM-2100PLUS透射电子显微镜操作方法与技巧及常见故障排除

以JEM-2100PLUS透射电子显微镜为例，介绍了电镜的基本结构、操作面板和成像原理。使用透射电子显微镜的最终目的就是要得到高质量的照片，结合透射电镜的操作步骤，总结了如何拍摄高质量的照片以及常见故障排除方法。     

电镜室杂散磁场测量的线圈制作和计算

环境杂散磁场影响电镜成像质量,在放大倍数高时更为严重。因此,在电镜安装和使用中,都要进行环境杂散磁场的测量。本文介绍一种测磁线圈的制作和计算。一、杂散磁场对电镜成像的影响: 我们曾在S—450扫描电镜和H—600透射电镜上做过试验,人为地加一个交变杂散磁场,这时拍下来的照片图象有严重畸变。图1为S—450没有受交变杂散磁场干涉的     

Improved focused ion beam target preparation of (S)TEM specimen--a method for obtaining ultrathin lamellae

Specimen quality is vital to (scanning) transmission electron microscopy (TEM) investigations. In particular, thin specimens are required to obtain excellent high-resolution TEM images. Conventional focused ion beam (FIB) preparation methods cannot be employed to reliably create high quality specimens much thinner than 20 nm. We have developed a method for in situ target preparation of ultrathin TEM lamellae by FIB milling. With this method we are able to routinely obtain large area lamellae with coplanar faces, thinner than 10 nm. The resulting specimens are suitable for low kV TEM as well as scanning TEM. We have demonstrated atomic resolution by Cs-corrected high-resolution TEM at 20 kV on a FIB milled Si specimen only 4 nm thick; its amorphous layer measuring less than 1 nm in total.     

Advanced TEM Characterization for Single-atom Catalysts: from Ex-situ Towards In-situ

Clean energy innovation has triggered the development of single-atom catalysts(SACs) due to their excellent catalytic activity, high tunability and low cost. The success of SACs for many catalytic reactions has opened a new field, where the fundamentals of catalytic property-structure relationship at atomic level await exploration, and thus raises challenges for structural characterization. Among the characterization techniques for SACs, aberration-corrected transmission electron microscopy(TEM) has become an essential tool for direct visualization of single atoms. In this review, we briefly summarize recent studies on SACs using advanced TEM. We first introduce TEM methods, which are particularly important for SACs characterization, and then discuss the applications of advanced TEM for SAC characterization, where not only atomic dispersion of single atoms can be studied, but also the distribution of elements and the valence state with local coordination can be resolved. We further extend our review towards in-situ TEM, which has increasing importance for the fundamental understanding of catalytic mechanism. Perspectives of TEM for SACs are finally discussed.     

TEM-induced structural evolution in amorphous Fe oxide nanoparticles

Exposure to the high energy electron beam of a TEM changes the morphology of amorphous Fe oxide nanoparticles from solid spheres to hollow shells. Amorphous Fe oxide nanoparticles prepared via high-temperature methods using hexadecylamine and trioctylphosphine oxide surfactants were compared to crystalline gamma-Fe2O3 particles of similar size. Both sets of particles are fully characterized via SQUID magnetometry, X-ray powder diffraction, BET surface analysis, EPR spectroscopy, high-resolution transmission electron microscopy (TEM), and electron energy loss spectroscopy (EELS). Time-resolved TEM images reveal that the amorphous Fe oxide particles evolve from solid spheres into hollow shells in <2 min, whereas crystalline gamma-Fe2O3 are unaffected by the electron beam. The resulting nanocrystalline Fe oxide shells bear striking resemblance to core-shell nanocrystals, but are a result of a morphology change attributed to restructuring of particle voids and defects induced by quasi-melting in the TEM. These results thus imply that caution is necessary when using TEM to analyze nanoparticle core-shell and heterostructured nanoparticles.     

Preparation of combinatorial arrays of polymer thin films for transmission electron microscopy analysis

We present a new method for harvesting multiple thin film specimens from polymer combinatorial libraries for transmission electron microscopy (TEM) analysis. Such methods are of interest to researchers who wish to integrate TEM measurements into a combinatorial or high-throughput experimental workflow. Our technique employs poly(acrylic acid) plugs, sequestered in an elastomer gasket, to extract a series of film patches from gradient combinatorial libraries. A strategy for simultaneous deposition of the array of film specimens onto TEM grids also is described. We demonstrate our technique using nanostructured polymer thin film libraries as test cases in which the nanoscale details can be successfully imaged. Microscopy of test case specimens demonstrates that these samples are of sufficient quality for morphology screening via TEM, and in some cases are sufficient for more detailed morphological studies.     

Transmission Electron Microscopy as a Powerful Tool for Investigating Lithium-ion Battery Materials

Transmission electron microscopy(TEM) stands out as one of the most powerful tools for characterizing materials at multiple scales and dimensions. This unique technique has nowadays been widely employed in investigating the lithium-ion battery(LIB) materials. The present perspective paper focuses on several LIB related aspects that are recently revealed by using TEM. Finally, we present outlook on the future directions of TEM for LIB research and development.     

Off-axis electron holography of unbiased and reverse-biased focused ion beam milled Si p-n junctions.

Off-axis electron holography is used to measure electrostatic potential profiles across a silicon p-n junction, which has been prepared for examination in the transmission electron microscope (TEM) in two different specimen geometries using focused ion beam (FIB) milling. Results are obtained both from a conventional unbiased FIB-milled sample and using a novel sample geometry that allows a reverse bias to be applied to an FIB-milled sample in situ in the TEM. Computer simulations are fitted to the results to assess the effect of TEM specimen preparation on the charge density and the electrostatic potential in the thin sample.     

TEM investigation of formation mechanism of monocrystal-thick b-oriented pure silica zeolite MFI film

The first direct transmission electron microscopic (TEM) observation has been carried out on the continuous monocrystal-thick b-oriented pure silica zeolite MFI films produced by in situ crystallization. The self-supporting film samples for TEM study were fabricated by dissolving the steel substrate with acid. This TEM study is free of those artifacts that are typically associated with TEM sample preparations, and allows us to investigate the "true" structure and texture of a very large area of the film and at the same time to focus at will on each individual zeolite crystal in the film. Abundant TEM information including crystallographic orientation relationships among crystals in the film (both out-of-plane and in-plane), grain boundaries, and each crystal grain was obtained. This TEM investigation provides direct unambiguous new evidence to support the homogeneous nucleation mechanism, by which the films form through homogeneous nucleation and crystal growth in the bulk to form equal-sized disk-shape crystals, followed by self-assembly of these crystals onto the substrate to produce a two-dimensional close-packed structure. The last stage of the film formation involves simultaneous space-limited growth and rotation of the individual crystals to realize the in-plane crystallographic control within the film.     

含C60球两亲分子有序聚集体研究

综合评述了C60两亲分子有序聚集体的形成、结构及聚集体演变规律,介绍了含C60球两亲分子有序聚集体结构的冷冻刻蚀电子显微镜和电子显微镜、小角度中子散射、小角度X光散射、激光光散射以及聚集体结构模型的研究结果.     

Identifying hexagonal boron nitride monolayers by transmission electron microscopy

Multislice simulations in the transmission electron microscope (TEM) were used to examine changes in annular-dark-field scanning TEM (ADF-STEM) images, conventional bright-field TEM (BF-CTEM) images, and selected-area electron diffraction (SAED) patterns as atomically thin hexagonal boron nitride (h-BN) samples are tilted up to 500 mrad off of the [0001] zone axis. For monolayer h-BN the contrast of ADF-STEM images and SAED patterns does not change with tilt in this range, while the contrast of BF-CTEM images does change; h-BN multilayer contrast varies strongly with tilt for ADF-STEM imaging, BF-CTEM imaging, and SAED. These results indicate that tilt series analysis in ADF-STEM image mode or SAED mode should permit identification of h-BN monolayers from raw TEM data as well as from quantitative post-processing.     

Visualized observation of pores in activated carbon fibers by HRTEM and combined image processor

Image analysis has been applied to the TEM observation of activated carbon fibers, in order to evaluate the pore structure visually. It is suggested that the present method can show the shape of the pores as well as providing a quantitative estimation of the pore structure. The results are consistent with those obtained by common gas adsorption method and with synthesized molecular graphics TEM images of pores. The pore analysis on activated carbon fibers by TEM combined with image processing can provide a powerful tool to characterize the porous structure of activated carbons from a different new viewpoint.