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  • 期刊名称:

    Scanning

  • 中文名称: 扫描
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  • ISSN: 0161-0457
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61条结果
  • 机译 通过外延和直接键合制备的双层硅结构的扫描电子显微镜研究
    摘要:The electrical properties of multilayer structures obtained by direct bonding of silicon wafers and epitaxial growth have been investigated. The measurements were made by scanning electron microscopy (SEM) in either secondary electron or electron beam-induced current (EBIC) regime, using cross sections of the structures with a p-n junction formed in the subsurface region of the active layer. The measurements of defect recombination activity were made using Schottky diodes formed on the active layer surfaces. Parasitic p-n junctions in some samples under a small direct voltage have been observed and the reason for the appearance of such parasitic junctions has been established. Two types of defects with different distribution densities and amplitudes of EBIC contrast have been detected.
  • 机译 使用光纤束的实时白光反射共聚焦显微镜
    摘要:We describe a real-time white light reflection con-focal microscope incorporating an optical fibre bundle and characterise the optical performance of the bundle. The use of an incoherent light source enables us, for the first time, to present speckle-free endoscopic reflected light confocal images. The system has potential application for in vivo studies.
  • 机译 鸡红细胞核小体沿连接子DNA-A扫描力显微镜研究的方向明确
    摘要:The orientation of nucleosomes was investigated using scanning force microscopy (SFM) of hypotonically spread chicken chromatin. A virtual cross section parallel to the substrate at half maximum height of the nucleosomal structure revealed an elliptical shape. The orientation of the major axis of this ellipse was investigated in reference to the direction of the axis of the nucleosomal chain. An alignment of the nucleosomes along the nucleosomal chain was observed, with more than 50% of the nucleosomes aligned with the long axis of the chain within ≤ 30° deviation. The alignment distribution peaked at 10-20°. The application of SFM-based image processing for the structural investigation of a protein-DNA complex demonstrates the potential for this approach in structural molecular biology.
  • 机译 赌场:电子束相互作用的C语言新蒙特卡罗代码-第二部分:莫特截面的列表值
    摘要:This paper presents routines to compute the Mott cross section used in the CASINO program (Monte CArlo Simulation of electroN trajectory in sOlid). The routines used tabulated values of the Mott cross section computed in the work of Czyzewski et al. (1990). The cross section is available over the range 0.02 to 30 keV and for the first 94 elements of the Periodic Table. The routines are written in C language and use a binary file to interpolate the cross section. The first routine computes the total Mott cross sections; the second calculates the polar angle of collision. Backscattered coefficients computed using different cross section are compared for C, Al, Ag, and Au. The Rutherford (1911) cross section and the available empirical equations (Browning et al. 1994, Gauvin and Drouin 1993) are compared to tabulated values of Mott. Also, the energy distribution of backscattered electrons is shown for Al and Au at 10 keV. Finally, the relative computation times for the different Mott cross sections are compared. It was found that tabulated Mott cross sections are more accurate and faster than any empirical Mott cross sections. The tabulated Mott cross sections are even faster than simple Rutherford cross sections.
  • 机译 低倍率扫描电子显微镜图像中几何畸变的评估和校正
    摘要:A method is introduced to assess and correct the geometric distortions which frequently occur in low-magnification scanning electron microscopy (SEM) images. Such images typically exhibit a complex pattern of varying deviations from orthogonality which cannot be adequately corrected by simple geometric transformations such as shifting, scaling, rotation, or shearing. A suitable approach to rectify low-magnification SEM images is polynomial warping, a correction procedure which also accomplishes rubber sheet transformation. To demonstrate the approach, a reference grid for low magnifications has been scanned at 40- and 55-fold magnifications by means of a microanalyzer. Calculated geometric distortions range from 1.5 to 3.5% of the image dimensions; applying polynomial warping, distortions could be reduced to approximately 0.1% of the image dimensions. Because of its easy application and the widespread availability in image processing packages, polynomial warping can be recommended as a routine procedure for rectifying low-mag-nificaton SEM images.
  • 机译 热环境下氧化物的彩色阴极发光研究
    摘要:The behavior of cathodoluminescence (CL) from oxides associated with plastic deformation as well as with annealing at different temperatures and atmospheres has been examined. Observations using the real color CL (CCL) mode in a scanning electron microscope show that the annealing temperature rather than the annealing atmosphere is the major factor influencing the observed changes in the spatial distribution of the total CL emission from the microdeformed surface. However, at the same annealing temperature, the spectral composition of the CL depends on the annealing atmosphere. An attempt has been made to explain the obtained results in terms of defect theory and radiation effects in electron microscopy.
  • 机译 赌场:电子束相互作用的C语言新蒙特卡罗代码-第三部分:低能量时的停止功率
    摘要:This paper is a description of the stopping power routine utilized in the CASINO program that is based on the experimental measurement of the energy loss function (ELF). In addition, we present an ANSI C standard program that can be used to generate the data needed for the stopping power routine. Both optical and energy loss spectrum (ELS) measurements of the ELF can be used as input to compute the stopping power. For ELS, only the single scattering spectrum is needed. Hence, measurement of the stopping power for a given element or compound of interest can easily be performed and used in the CASINO program. The resulting effect of using these stopping powers in Monte Carlo simulations is generally to increase the backscattering coefficient. Except for carbon, the change of stopping power for pure elements so far compiled is relatively small. In some compounds (i.e., Al_2O_3 and ZnSe), the discrepancy with the Joy and Luo (1989) expression is significant.
  • 机译 赌场:电子束相互作用的C语言新蒙特卡罗代码-第一部分:程序说明
    摘要:This paper is a guide to the ANSI standard C code of CASINO program which is a single scattering Monte CArlo Simulation of electroN trajectory in sOlid specially designed for low-beam interaction in a bulk and thin foil. CASINO can be used either on a DOS-based PC or on a UNIX-based workstation. This program uses tabulated Mott elastic cross sections and experimentally determined stopping powers. Function pointers are used for the most essential routine so that different physical models can easily be implemented. CASINO can be used to generate all of the recorded signals (x-rays, secondary, and backscattered) in a scanning electron microscope either as a point analysis, as a linescan, or as an image format, for all the accelerated voltages (0.1-30 kV). As an example of application, it was found that a 20 nm Guinier-Preston Mg_2Si in a light aluminum matrix can, theoretically, be imaged with a microchannel backscattered detector at 5 keV with a beam spot size of 5 nm.
  • 机译 通过红外室内镜和反射镜,在环境扫描电子显微镜内部实现更好的可视化
    摘要:Clearances are tight inside the specimen chamber of the environmental scanning electron microscope (ESEM), and it is difficult to see the relative positions of detectors and specimens through the viewport. For example, the relative placement of the energy-dispersive spectrometer (EDS) and the specimen is critical for attaining reasonable x-ray efficiency while protecting the detector window from damage. An infrared chamberscope and mirror attachment were added to improve the visibility inside the chamber.
  • 机译 在环境扫描电子显微镜中优化接头材料研究对比度的某些方面
    摘要:In the environmental scanning electron microscope, material joints of different atomic mass and different electrical conducting properties can easily be observed simultaneously without coating the specimen. For such heterogeneous materials, the quality of the image can be optimized with respect to contrast and resolution if the contrast types as well as their significance to the composition of the image are known.
  • 机译 环境恶化的环境扫描电子显微镜研究
    摘要:Case studies will be presented in which environmental scanning electron microscopy (ESEM) has been used to provide unique insight into the role of microorganisms in deterioration processes. ESEM is an excellent tool for demonstrating spatial relationships between microorganisms and substrata because hydrated, nonconducting samples can be viewed with a minimum of manipulation. Copper and iron-rich deposits associated with bacteria were detected within corrosion layers on copper and steel surfaces, respectively. Fungal mycelia growing on wooden storage spools were shown to penetrate protective grease on carbon steel wire rope in contact with the spool and to cause localized corrosion. Large numbers of marine bacteria were documented within paint blisters and disbonded regions of fiber-reinforced polymeric composites. In both cases, it appears that microbial gas production resulted in mechanical damage to the substrata.
  • 机译 某些仪器操作条件对环境扫描电子显微镜中颗粒的X射线显微分析的影响
    摘要:The objective of this investigation was to evaluate the practical effects of electron beam broadening in the environmental scanning electron microscope (ESEM) on particle x-ray microanalysis and to determine some of the optimum operating conditions for this type of analysis. Four sets of experiments were conducted using a Faraday cage and particles of copper, glass, cassiterite, and rutile. The accelerating voltage and chamber pressure varied from 20 to 10 kV and from 665-66 Pa (5.0 to 0.5 torr), respectively. The standard gaseous secondary electron detectors (GSED) and the long environmental secondary dectectors (ESD) for the ESEM were evaluated at different working distances. The effect of these parameters on the presence of artifact peaks was evaluated. The particles were mounted on carbon tape on an aluminum specimen mount and were analyzed individually and as a mixture. Substrate peaks were present in almost all of the spectra. The presence of neighboring particle peaks and the number of counts in these depended upon the operating conditions. In general, few of these peaks were observed with the long ESD detector at 19 mm working distance and at low chamber pressures. More peaks and counts were observed with a deviation from these conditions. The most neighboring peaks and counts were obtained with the GSED detector at 21.5 mm working distance, 10 kV accelerating voltage, and 665 Pa (5.0 torr) chamber pressure. The results of these experiments support the idea that the optimum instrumental operating conditions for EDS analysis in the ESEM occur by minimizing the gas path length and the chamber water vapor pressure, and by maximizing the accelerating voltage. The results suggest that the analyst can expect x-ray counts from the mounting materials. These tests strongly support the recommendation of the manufacturer to use the long ESD detector and a 19 mm working distance for EDS analysis. The results of these experiments indicate that neighboring particles millimeters from the target may contribute x-ray counts to the spectrum.
  • 机译 环境扫描电子显微镜中高分辨率能量色散X射线分析的新校正方法
    摘要:Spurious x-ray signals, which previously prevented high-resolution energy-dispersive x-ray analysis (EDS) in the environmental scanning electron microscope (ESEM), can be corrected using a simple method presented here. As the primary electron beam travels through the gas in the ESEM chamber, a significant fraction of the primary electrons is scattered during collisions with gas molecules. These scattered electrons form a broad skirt that surrounds the primary electron beam as it impacts the sample. The correction method assumes that changes in the width of the electron skirt with pressure are less important than changes in the skirt intensity; this method works as follows: The influence of the gas on the overall x-ray data is determined by acquiring EDS spectra at two pressures. Subtracting the two spectra provides us with a difference spectrum which is then used to correct the original data, using extrapolation, back to the x-ray spectrum expected under high-vacuum conditions. Low-noise data are required to resolve small spectral peaks; however, the principle should apply equally to x-ray maps and even to low-magnification images.
  • 机译 使用环境扫描电子显微镜观察纤维素纤维的溶胀行为
    摘要:We have developed a method for observing transverse swelling of cellulosic fibres in the environmental scanning electron microscope (ESEM). The presence of liquid water in the ESEM specimen chamber allows the observation of in situ hydration without the need for coating, freezing, or drying of the sample. For reproducibility of the hydration and dehydration process, specialised mounting techniques are required and control of the conditions for condensation and evaporation of liquid water is necessary. The sensitivity of these cellulosic materials to the electron beam was investigated, showing that some damage mechanisms are enhanced by the continual presence of water vapour in the chamber. A discussion is presented of the effect of various experimental parameters on the extent and time of onset of the damage, and we outline steps to maximise the amount of useful experimental time for these fibres.
  • 机译 使用环境扫描电子显微镜表征Polyox〜®颗粒
    摘要:The scanning electron microscope (SEM) has been frequently used in the pharmaceutical industry for studying pharmaceutical products. However, the technique does not allow for the continuous characterization of a product in both dry and hydrated states without processing the product. Through the recent advent of the environmental scanning electron microscope (ESEM), it is now possible to observe a sample in both the dry and hydrated states without extensive product preparation. The ESEM also allows for continual observation during the hydration process from the dry state until the sample is dissolved. In this study, the ESEM was used to characterize the morphologic differences and hydration patterns of granules formulated with a water-soluble hydrophilic swelling polymer, Polyox~®. Two molecular weights (1,000,000 and 7,000,000) of the polymer were used in concentrations ranging from 10 to 25% w/w. Visual differences in granule surface morphology and differences in hydration patterns were seen in granules prepared from different polymer concentrations. The morphologic data were corroborated by surface area measurements taken on a surface area analyzer. The rate at which the granule dissolved in the ESEM also correlated with the drug dissolution times determined by the standard USP dissolution method.
  • 机译 硼粒子燃烧扩散机理的环境扫描电子显微镜研究
    摘要:This investigation was performed to resolve long-term contradicting theories regarding the mechanisms which govern the species diffusion across the liquid B_2O_3 layer covering a single boron particle during the combustion of boron. An environmental scanning electron microscope (ElectroScan E-3) was used to observe the liquefaction characteristics of the boron oxide layer and to examine boron dissolution and species diffusion processes in real time. Using a hot stage, crystalline boron particles were heated from 25 to 950℃ in O_2, H_2O, or Ar environments. Pure B_2O_3 particles were also heated in an O_2 environment and examined. In situ observations showed that the diffusion of dissolved boron into molten B_2O_(3(1)) is much more dominant at elevated temperatures than the diffusion of gaseous O_2 through the B_2O_(3(1)) layer. Dissolution of solid boron into the boron oxide layer caused the liquefaction of boron particles at relatively low temperatures (940℃). The chemical composition of liquid boron oxide, coated on the surface of boron particles, was identified as a polymeric vitreous (BO)_n complex through the reaction between dissolved boron and molten B_2O_(3(1)).
  • 机译 自组装单分子层和二次离子质谱法开发环境扫描电子显微镜电子束轮廓成像
    摘要:A method for demonstrating the scattering of the primary electron beam in the presence of a gas has been developed. A self-assembled decanethiol monolayer is damaged by primary beam electrons. The damaged portion of the mono-layer is exchanged with another thiol-containing molecule by immersion in solution. The resulting film is imaged using a secondary ion mass spectrometer. Three-dimensional reconstruction of the data yields a representation of scattered electrons in the gaseous environment of the environmental scanning electron microscope.
  • 机译 环境扫描电子显微镜中的原位激光加热
    摘要:The environmental scanning electron microscope (ESEM) offers improved capabilities for coupling a scanning electron microscope (SEM) with an in situ laser device compared with conventional SEMs. Such coupling generally enables, for example, the observation of laser glazing effects or high-temperature behaviour as well as thermal shock behaviour of materials and devices. In an ESEM, decomposition caused by high-temperature gas reactions can additionally be studied while monitoring the gaseous environment online with a mass spectrometer attached to the specimen chamber. In this work, we demonstrate the capabilities of an in situ laser system suitable for heating specimen in an in situ deformation stage, thus enabling the further study of the mechanical properties of materials far beyond temperatures accomplished by thermal heating stages.
  • 机译 环境扫描电子显微镜专刊第二部分
    摘要:The papers in this issue of SCANNING constitute the conclusion of the special issue on environmental scanning electron microscopy (SEM) which was initiated with the October 1996 issue. Taken together, the 20 papers in this collection provide the reader with a broad overview of environmental SEM as it is applied in diverse scientific and technological fields.
  • 机译 个人和家用产品的环境扫描电子显微镜
    摘要:The ability to forego sample preparation and to make observations directly in the environmental scanning electron microscope has benefited both household and personal product research at Unilever Research. Product efficacy on biological materials such as microcomedones was easily ascertained. Skin biopsies were examined in a moist state with no sample preparation. Effects of relative humidity on detergents were visually determined by recreating the necessary conditions in the microscope. Effects of cooling rates on the morphology of softener sheet actives that remained on polyester fabric were characterized via dynamic experimentation.
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