Showing papers on "Electron tomography published in 1987"
58 citations
TL;DR: In this paper, the combined application of imaging, diffraction and spectroscopic methods, using either a dedicated scanning transmission electron microscope or a conventional high-resolution electron microscope (having a strong objective lens) equipped with suitable X-ray or electron spectrometers.
Abstract: Analytical electron microscopy enables combined crystallographic and chemical information with a high spatial resolution to be gained from microregions of electron-transparent specimens. This is reached by the combined application of imaging, diffraction and spectroscopic methods, using either a dedicated scanning transmission electron microscope or a conventional high-resolution electron microscope (having a strong objective lens) equipped with suitable X-ray or electron spectrometers. Of the diffraction methods especially the technique of convergent beam diffraction is used, yielding valuable information on crystal structures, lattice parameter changes, symmetry variations and crystal perfection, respectively. For chemical analysis, either energy-dispersive X-ray spectroscopy (EDX) is used or electron energy loss spectroscopy (EELS). Finally, high-resolution electron microscopy in the lateral resolution range of some 0.1 nm allows the reliable geometrical inspection of extreme microregions.
22 citations
TL;DR: In this article, a theory of the formation of electron microscope images at atomic resolution, the influence of aberrations, the properties of the transfer function, and the methods of processing, calculating, and interpreting images are presented.
Abstract: Contemporary transmission electron microscopes have resolutions down to 1.5–2 A, and this enables one to observe atoms directly. A theory is presented of the formation of electronmicroscope images at atomic resolution, the influence of aberrations, the properties of the transfer function, and the methods of processing, calculating, and interpreting images. The relation is examined between electron microscopy and electron diffraction. Examples are given of electron-microscope studies of the atomic structure of various objects—molecules, crystals, various organic and inorganic compounds, including minerals and semiconductors, and of studies of defects of crystal-structure and of its formation during crystal growth.
13 citations
TL;DR: In this article, a modified commercial scanning electron microscope equipped with a field-emission gun was used for routine work, especially in the field of biology where one may expect to utilize digital image processing techniques.
Abstract: Recently, the reliability of field-emission electron guns has increased. In addition, the cost of computer systems for on-line processing has dropped. Hence, we should now consider the use of scanning transmission electron microscopy (STEM) for routine work, especially, in the field of biology where one may expect to utilize digital image processing techniques.
An STEM has been constructed, without disturbing the original functions, by converting a commercial scanning electron microscope equipped with a fieldemission gun. The STEM is generally operated at accelerating voltage 30 kV, focal length 7.5 mm, and beam current 1−2 × 10−10 A. Several improvements have been incorporated for removing the effects of vibration, contamination, and stray magnetic fields. Also, an adjustable detector aperture was utilized. The modified instrument was connected to an on-line digital image processing system for utilizing the information obtained from STEM images. The advantages of the modified system were studied from various viewpoints.
11 citations
TL;DR: Elements of high atomic number backscatter electrons that carry information of cytochemical and of immunocytochemical significance in high resolution scanning electron microscopy (SEM) have been used to localize the sites of phosphatase and of endogenous peroxidase.
Abstract: Elements of high atomic number backscatter electrons that carry information of cytochemical and of immunocytochemical significance in high resolution scanning electron microscopy (SEM). Reaction products of enzyme cytochemistry containing lead or osmium have been used to localize the sites of phosphatase and of endogenous peroxidase, respectively. Particles of colloidal gold, ranging in diameter from 40 to 13 nm, have been successfully used to label cell surface antigens specifically identified by murine monoclonal antibodies. The diagnostic potential of the scanning electron microscope in clinical hematology appears to be considerably enhanced by the use of the backscattered electron imaging (BEI) mode. Quantitation of the number of gold-labeled epitopes on cell surfaces cannot be achieved in the conventional secondary electron mode of the SEM, but is an attractive possibility in the backscattered electron imaging mode.
8 citations
TL;DR: In this article, the effects of electron beam energy and phase angle on scanning electron acoustic images of the thermal and elastic properties of surfaces were studied with an alumina fiber/aluminum matrix composite for fiber directions both transverse and coaxial to the surface.
Abstract: Scanning electron acoustic microscopy is a new technique for imaging the thermal and elastic properties of surfaces and detecting subsurface flaws. It can be carried out in a modified scanning electron microscope. The effects of electron beam energy and phase angle on scanning electron acoustic images of the thermal and elastic properties of surfaces were studied with an alumina fiber/aluminum matrix composite for fiber directions both transverse and coaxial to the surface. Images produced with 10- and 30-keV electrons at beam modulation frequencies of 80–1200 kHz appeared to be identical, with the exception of a lower signal-to-noise ratio for the lower electron energy. This observation suggests that the energy input from the beam can be considered to occur at the surface for electron energies below 30 keV and frequencies below 1200 kHz. Images recorded at 0° phase angle mapped regions of different thermal and elastic properties. Images recorded at 90° phase angle highlighted the boundaries between such regions. Scanning electron acoustic microscopy can image features of different thermal and elastic properties at greater depth than traditional imaging with backscattered electrons. The practical application of the technique to the study of surfaces is illustrated by the imaging of grain structure and subsurface particles for an extruder barrel.
5 citations
Patent•
05 May 1987
5 citations
TL;DR: In this article, two different geometric methods for the three-dimensional reconstruction of electron microscope objects from a set of scanning electron micrographs are used to study the geometry of V-groove structures prepared by anisotropic etching of 100 silicon.
4 citations
TL;DR: In this article, the spin polarization of secondary electrons is measured by scanning electron microscopy with polarization analysis (SEMPA) to directly measure the magnitude and direction of the magnetization and the direction of magnetization in the region probed by the incident electron beam.
Abstract: The recent joining of scanning electron microscopy and electron spin polarization analysis has greatly improved the ability to study magnetic microstructure.1,2 By measuring the spin polarization of secondary electrons, scanning electron microscopy with polarization analysis (SEMPA) can directly measure the magnitude and direction of the magnetization and direction of the magnetization in the region probed by the incident electron beam. This region is defined by the diameter of the incident electron beam (∼10 nm) and the escape depth of the secondaries (∼5 nm). In addition to the purely magnetic image SEMPA also simultaneously and independently measures the usual topographic image, thereby making comparisons between magnetic and topographic structures easier. We have successfully used SEMPA to study magnetic structures in Fe crystals, permalloy films, CoNi recording media, and metglasses. Examples from this work will be given in order to demonstrate the unique capabilities of SEMPA.
3 citations
TL;DR: The scanning transmission electron microscope (STEM) with backscattered and secundary electron detectors can be used as a tool for characterization and localization of small particles at the surface and in the coating of magnetic tapes as discussed by the authors.
Abstract: The scanning transmission electron microscope (STEM), with backscattered and secundary electron detectors, can be used as a tool for characterization and localization of small particles (<1 μm) at the surface and in the coating of magnetic tapes. The combination of energy dispersive X-ray microanalysis with STEM provides information about the chemical composition of the particles of interest.
2 citations
03 Aug 1987
TL;DR: In this paper, the authors used scanning electron acoustic microscopy (SEAM) for the analysis of human bone and brain micrographs of the human brain and showed its large range of applicability in materials research and engineering, is now applied to medical research.
Abstract: Scanning electron acoustic microscopy (SEAM ) is an operation mode within scanning electron microscopy utilizing the sound or ultrasound generation within the sample due to the impact of a temporarily modulated electron beam current. This technique, which has already shown its large range of applicability in materials research and engineering, is now applied to medical research. Applications presented in this paper are shown for SEAM micrographs of human bone and brain.
TL;DR: In this paper, the secondary electron image consists of different quantities of secondary electrons depending on whether the primary electron beam is deflected to impinge on the specimen or not as a result of the horizontal component of the leakage magnetic field.
Abstract: A method for observing magnetic fields is proposed, in which a primary electron beam is directed parallel to the specimen surface. The leakage magnetic field due to recorded magnetization patterns is observed as a secondary electron image using a scanning electron microscope. The secondary electron image consists of different quantities of secondary electrons, depending on whether the primary electron beam is deflected to impinge on the specimen or not as a result of the horizontal component of the leakage magnetic field. Secondary electron images obtained for perpendicular recording and for longitudinal recording are presented. Recording lengths as short as two microns can be resolved by this method.
TL;DR: In this article, the advances achieved by the method of electron microdiffraction in the study of the crystal structures of organic polymers with the aid of the transmission electron microscope are examined and the advantages and disadvantages of the method are analysed.
Abstract: The advances achieved by the method of electron microdiffraction in the study of the crystal structures of organic polymers with the aid of the transmission electron microscope are examined and the advantages and disadvantages of the method are analysed. It is shown that the diffraction studies on polymers in a transmission electron microscope not only supplement X-ray data but in many cases provide unique possibilities for structural analysis. The applied aspect of the structural studies of polymers is examined and methods are described for the preparation of the specimens and for protecting the polymeric object from the action of radiation. The bibliography includes 122 references.