背散射电子成像与能谱技术结合用于金属负载型催化剂的分散性研究

扫描电子显微(配备能谱仪附件)技术作为表面微观分析的重要手段之一,可充分展现催化剂的表面形貌和微区成分,对催化剂的研制和开发具有重要意义.本文将背散射电子成像与X射线能谱仪结合,研究了 Au-Ni复合催化剂的表面形貌及活性组分的分散状态,并详细探讨了图像清晰度与扫描速度、工作电压、工作距离等的关系.研究发现,在扫描速度...     

扫描电镜与能谱仪

<正>扫描电镜利用精细聚焦电子束照射在样品表面,该电子束可以是静止或在样品表面作光栅扫描。在这个过程中,电子束与样品相互作用产生各种信号,其中包括二次电子、背散射电子、俄歇电子、特征X射线和不同能量的光子等,这些信号来自样品中的特定区域,分别利用探测器接收,可以提供样品的各种信息,用于研究材料的微观形貌、晶体学特征和微区化学成分。X射线能谱仪是扫描电镜附带的附件,通过检测从样品出射的特征X射线的波长或能量,测定样品元素的组成、相对含量以及分布。     

珍珠形胆结石的红外光谱和扫描电镜分析

磁疗获得的珍珠形胆结石是罕见的病例,作者利用红外光谱、扫描电子显微镜及Ｘ射线能谱对该胆结石进行了观察和研究。结果表明该胆结石的主要成分为胆固醇,并混有少量的蛋白质和无机钙盐,说明珍珠形胆结石虽然和珍珠具有相似的形貌,但组成是完全不同的。根据扫描电子显微镜的照片,作者推测结石的珍珠外形可能是因为片状的胆固醇分子形成胆甾型晶体而形成的。     

硅烷化光纤表面微结构成分的扫描电镜及能谱仪联用表征

采用扫描电镜和能谱仪检测细小的硅烷化光纤表面微结构成分,表征了光纤与3-氨基丙基-三乙氧基硅烷(APTES)的耦合.能谱分析显示,未硅烷化的光纤表面无碳原子,而硅烷化的光纤表面含有碳原子,其碳原子质量分数为13.74%、16.72%,说明在细小光纤表面上耦合了APTES.经扫描电镜与能谱联用表征光纤表面微结构成分发现,不同表面检测微区域,碳的质量分数不同.探讨了硅烷化的光纤与吖啶橙(AO)的相互作用,并考察了酸性介质对其荧光强度的影响.结果表明:硅烷化的光纤与吖啶橙相互作用发出荧光,证明硅烷化的光纤表面有活性基团;经稀盐酸洗涤后,荧光强度减弱,表明光纤表面的活性基团与AO通过非共价键结合.研究表明,两种方法均能表征细小光纤或纳米光纤与硅烷双功能剂的耦合,以及光纤生物传感器敏感元件的靶分子检测.     

断口定量分析中高度参数的扫描电镜测定

在断口定量分析中根据双目成象原理,运用扫描电镜技术,实现对断口上高度参数的测量,将扫描电镜中获得的立体感觉转变为相应的几何参数,从而可以从断口上获得高度参数的定量数据。同时还分别讨论了进行断口高度参数测量的倾转法和剖面法。     

扫描电镜在多晶硅电池片焊带分析中的应用

对多晶硅电池片焊带接口进行金相包埋,利用扫描电镜(SEM)表征,观察焊带与硅片结合处的图像及其成分分布,进而了解焊接情况,为工艺优化提供技术支撑.     

扫描电镜-能谱法测定生活饮用水中石棉

建立了扫描电镜-能谱法(SEM-EDS)测定生活饮用水中石棉(≥10μm)的方法,使用场发射扫描电镜可对宽度大于0.050~0.124μm的石棉纤维进行定性和计数。若生活饮用水中存在以藻类为主的有机质干扰,使用紫外-过硫酸钾消解可消除相应干扰。配置低、中、高3个浓度的石棉悬浊液模拟水样交由国内不同地区的6家实验室进行方法学验证,结果表明,方法实验室内RSD为10%~37%,实验室间RSD为10%~39%,蓝藻干扰消除实验回收率平均值为98.1%,RSD为11%。方法检出限为5.0×10^4~11.6×10^4个/L,低于GB 5749限量规定的700×10^4个/L。     

用扫描电镜和能谱仪进行金矿鉴定的研究

运用扫描电子显微镜（ＳＥＭ）及Ｘ射线能谱仪（ＥＤＸ）进行金矿鉴定的实验研究，结果表明，本法比较直观、简便，可以确定金的存在形式及生成环境，并鉴定金矿物的种类     

扫描电镜附EDS能谱仪的使用与维护

简单描述了扫描电镜中几种样品的制备方法以及操作中需要注意的事项,例如参数的选择、和峰和逃逸峰的处理等,并结合实例进一步简述了如何进行日常保养和维护.     

Imaging and Microanalysis in Environmental Scanning Electron Microscopy

A variety of gas cascade amplification and signal detection strategies have evolved for use in low vacuum and environmental scanning electron microscopy on poorly conducting specimens. These detectors have been optimized to perform well under various limitations on the range of gas pressure and working distance which may be imposed by experimental requirements. All of the detectors must produce high gains, low backgrounds, and generate a sufficient positive ion flux to the specimen to enable charge neutralization. The underlying principles of operation of each detector type are discussed, along with the range of experimental conditions appropriate to each.     

Studying Ice with Environmental Scanning Electron Microscopy

Scanning electron microscopy (SEM) is a powerful imaging technique able to obtain astonishing images of the micro- and the nano-world. Unfortunately, the technique has been limited to vacuum conditions for many years. In the last decades, the ability to introduce water vapor into the SEM chamber and still collect the electrons by the detector, combined with the temperature control of the sample, has enabled the study of ice at nanoscale. Astounding images of hexagonal ice crystals suddenly became real. Since these first images were produced, several studies have been focusing their interest on using SEM to study ice nucleation, morphology, thaw, etc. In this paper, we want to review the different investigations devoted to this goal that have been conducted in recent years in the literature and the kind of information, beyond images, that was obtained. We focus our attention on studies trying to clarify the mechanisms of ice nucleation and those devoted to the study of ice dynamics. We also discuss these findings to elucidate the present and future of SEM applied to this field.     

低电压扫描电子显微术

低电压扫描电子显微术是研究半导体、绝缘体和生物材料的有效方法。本文综述了这种方法的优点、限制和关于扫描电镜的改进,并且提供了实际操作的某些要领。     

Development of In Situ Electrochemical Scanning Electron Microscopy with Ionic Liquids as Electrolytes

We report that ionic liquids (ILs) can be observed by electron microscopy without any charging of the liquid. Based on this, we present an in situ electrochemical scanning electron microscopy (in situ ECSEM) system. The key technology that enables in situ ECSEM is that charges can be removed from an IL by grounding it with a Pt wire, even if the IL is in an insulating glass cell. As a first demonstration, we describe the redox reaction of a polypyrrole (PPy) film accompanied by changes in its thickness when it is polarized by the film‐deposited Pt electrode in the IL. Furthermore, energy‐dispersive X‐ray fluorescence (EDX) analysis can be employed for the electrode polarized in the IL. The component analysis by EDX of PPy in an IL containing K⁺ as a marker, reveals doping of electrolyte cations into the PPy film upon the latter′s reduction and dedoping of cations from the film upon oxidation.     

Orientation Imaging in Scanning Electron and Transmission Electron Microscopy for Characterization of the Shear Banding Phenomenon

The texture evolution during deformation of high purity fcc single crystals with initial (112) [11 ] orientation has been characterised in detail by transmission (TEM) and scanning (SEM–FEG) electron microscopes. The channel-die deformed samples up to reduction of about 1–1.5, first developing strongly anisotropic layers of elongated cells or twin-matrix plates and then compact clusters of SB. Substantial progress in understanding the mechanism of the SB formation was possible thanks to systematic local orientation measurements (orientation mapping) using SEM and TEM. These two techniques of local orientation measurements have been compared with respect to their applicability for the study of shear banding phenomenon and for characterization of the specific nanostructure of SB in metals with fcc lattice. It was shown that well-developed SB exhibit large orientation spreads up to 35–40° with respect to the adjacent areas outside the band. Most of these misorientations occur by rotations about the TD‖〈110〉 axis with significant further rotations about 〈112〉 poles. This ultimately leads to the formation of the texture components whose occurrence cannot be explained by models homogeneous deformation.     

Scanning Probe Microscopy beyond Imaging: A General Tool for Quantitative Analysis

A simple, fast and general approach for quantitative analysis of scanning probe microscopy (SPM) images is reported. As a proof of concept it is used to determine with a high degree of precision the value of observables such as 1) the height, 2) the flowing current and 3) the corresponding surface potential (SP) of flat nanostructures such as gold electrodes, organic semiconductor architectures and graphenic sheets. Despite histogram analysis, or frequency count (Fc), being the most common mathematical tool used to analyse SPM images, the analytical approach is still lacking. By using the mathematical relationship between Fc and the collected data, the proposed method allows quantitative information on observable values close to the noise level to be gained. For instance, the thickness of nanostructures deposited on very rough substrates can be quantified, and this makes it possible to distinguish the contribution of an adsorbed nanostructure from that of the underlying substrate. Being non‐numerical, this versatile analytical approach is a useful and general tool for quantitative analysis of the Fc that enables all signals acquired and recorded by an SPM data array to be studied with high precision.     

电子显微技术应用于生物纳米材料表征与测试的研究进展

该文简述了电子显微技术的发展历程,并介绍了现代电子显微镜的新功能。针对生物纳米材料理化性能与功能应用的特殊性,结合研究实例,重点阐述运用电子显微结构表征与原位分析测试技术指导构建新颖纳米结构、揭示材料与细胞/组织相互作用并发挥功能的机制。并在此基础上,展望了电子显微技术在生物纳米材料研究领域的发展方向(大尺寸图像拼接、三维重构、动态原位实时成像)。     

Orientation Imaging Microscopy for the Transmission Electron Microscope

The resolution limit of Orientation Imaging Microscopy in the Scanning Electron Microscope is between 20 nA and 80 nA depending on the basic resolution/beam current performance of the SEM, the sample atomic number and the level of residual strain within it. The newer technique of orientation imaging in the transmission electron microscope, TEM, improves on this resolution limit by a factor of five to ten. The new technique is based on a novel procedure for determining the crystallography of separate small volumes in the sample by examination of a large series of dark field images. Each image is recorded for a different diffraction condition. This is achieved by using a computer to direct the electron beam onto the same area of the sample so that it covers all directions within a cone of semi-apex angle 3 degrees. Analysis of the intensity of the same point in each of the dark field images permits reconstruction of a diffraction pattern for that point providing the data to calculate its crystal orientation. The process is repeated for each point in the image. The Orientation Image Micrograph is constructed from the orientations so determined. The technique is shown to be capable of producing orientation micrographs of high spatial resolution for unstrained samples. For highly strained samples difficulties are encountered in accurately indexing the complicated diffraction patterns that are observed. Methods to improve the indexing procedures involve determining the sub-cell structure first from a comparison of patterns from adjacent pixels and then summing all patterns belonging to a single sub-cell. The resultant improvement in pattern quality permits more reliable determination of orientation. Examples of this procedure are taken from studies of deformed aluminum.     

New Routes to High Resolution and Automated Polymer Morphology Microscopy via Scanning Electron Microscopy

Summary: Polymer morphologies are traditionally studied by transmission electron microscopy (TEM). With the use of appropriate contrast enhancing heavy metal stains, direct images of the morphology as well as of the lamellar structure of semi-crystalline polymers can be obtained. Despite its clear strengths, this approach faces several challenges and difficulties: the laborious nature of ultra-thin section preparation, high capital investment, and no obvious routes to high-throughput. We propose an alternative approach to cover the major morphology imaging needs based on a new generation of high resolution scanning electron microscopes (SEM) that have been developed in recent years, and that does not rely on the need for ultra-thin section preparation. The proposed approach is capable of not only determining the general phase morphology, but also to image details such as the lamellar structure with sufficient resolution. Our approach is based on the use of backscattered electron imaging at low accelerating voltages. The backscattered electron images show high contrast and information content that is comparable to TEM. The main advantage of our SEM based approach is the ability to examine a polished surface, which requires less demanding sample preparation than producing ultra-thin sections. This opens the door to automated workflows where automated imaging, substantial productivity increases and high speed characterization options can be successfully realized. The successful approach is demonstrated for various polyolefin and engineering plastics samples.