Showing papers on "Electron tomography published in 1973"
1,123 citations
TL;DR: In this paper, the angular distribution of back-scattered electrons can be observed in a scanning electron microscope, and the patterns observed can be used to obtain crystallographic information about the specimen.
Abstract: It is shown that the angular distribution of back-scattered electrons can be observed in a scanning electron microscope, and that the patterns observed can be used to obtain crystallographic information about the specimen. The patterns are termed electron back-scattering patterns (E.B.S.P.). The use of these patterns as a crystallographic techniques is shown to have several significant advantages over two other techniques currently in use in scanning electron microscopes.
422 citations
TL;DR: In this paper, the amplitude and phase from the intensity distribution of an electron micrograph is estimated using the relative defocus between micrographs, and the procedure is valid both in bright field and dark field microscopy for any specified coherence of the electron source.
Abstract: A method is given for the evaluation, in transmission electron microscopy, of the amplitude and phase from the intensity distribution of an electron micrograph. The method requires a minimum of two micrographs taken under different defocus conditions. The iterative scheme requires only the relative defocus between micrographs, and the procedure is valid both in bright-field and dark-field microscopy for any specified coherence of the electron source. Assumptions on the scattering properties of the specimen, such as the weak-phase-weak-amplitude object, are not required. For a complete determination of the amplitude-phase distribution for electron transmission through the specimen, the electron micrograph must be corrected for the effect of lens aberrations and defocusing to give the electron wavefunction immediately after transmission; only in the case of a weak-phase object can this wavefunction be directly related to the projected potential distribution in the object. Inelastic electron scattering is explicitly omitted from the analysis presented.
238 citations
TL;DR: In this paper, an electron interference experiment that provides impressive evidence of the wave-like behavior of electrons has been performed, where a standard electron microscope is used as an electron-optical bench.
Abstract: An electron interference experiment that provides impressive evidence of the wave-like behavior of electrons has been performed. The interferometric device has been designed as simply as possible and is described in detail. A standard electron microscope is used as an electron-optical bench.
77 citations
57 citations
TL;DR: In this paper, the angular and energy characteristics of the transmitted electron beam are important in the determination of the effects of phase shifts introduced by the spherical aberration and the chromatic aberration of the objective lens.
Abstract: Publisher Summary This chapter describes image formation in the electron microscope with particular reference to the defects in electron-optical images. In the transmission electron microscope, information on the structure of a specimen, through its electron scattering properties, is transmitted to an image plane by a set of electron lenses. The intensity distribution, with respect to the angular deviation and the energy change of the incident electron beam, may be determined experimentally, but the information required on the amplitude and phase of the scattered electron wave may be inferred only by a detailed comparison of theory and experiment. The formation of an image from the scattered wave may be expressed mathematically in terms of a Fourier transformation. The chapter states that the angular and energy characteristics of the transmitted electron beam are important in the determination of the effects of phase shifts introduced by the spherical aberration and the chromatic aberration of the objective lens.
37 citations
TL;DR: In this article, the defect structure of TiO 2 ·7Nb 2 O 5 has been examined at about 0.3 nm resolution in an electron microscope under suitable conditions of crystal orientation and objective lens defocus, the contrast in images from very thin fragments can be interpreted directly in terms of structure.
24 citations
TL;DR: The purpose of this review is to present in outline the subject of transmission scanning microscopy, the advocated advantages in comparison with conventional transmission microscopy and some of the achieved and potential applications.
Abstract: The availability of scanning attachments for transmission microscopes and the advent of very high resolution scanning microscopes now enables materials to be studied in both the back scattered and transmission scanning modes. It is the purpose of this review to present in outline the subject of transmission scanning microscopy, the advocated advantages in comparison with conventional transmission microscopy and some of the achieved and potential applications.
18 citations
12 citations
TL;DR: The elastic and inelastic image profiles for the transmission electron microscopy of amorphous (biological) materials, corresponding to objective lens defocus values, 0 to -2000 nm for an incident electron energy of 100 keV, are presented.
Abstract: Calculations are presented for the elastic and inelastic image profiles for the transmission electron microscopy of amorphous (biological) materials, corresponding to objective lens defocus values, 0 to -2000 nm for an incident electron energy of 100 keV, used in the electron microscopy of biological specimens. These calculations are relevant to image analysis procedures which neglect the contribution of the inelastic electron scattering to the image intensity for these large underfocus values. For small defocus values, 0 to -200 nm, the inelastic contribution can be described as an unstructured background in the electron micrograph. However, corresponding to the larger underfocus values, -500 to -2000 nm, the elastic image resolution is inferior to that of the inelastic image. The inelastic image resolution is less dependent on the objective defocus value than the elastic image resolution, and in dark-field microscopy at defocus values -500 to -2000 nm, the inelastic image is of primary importance. In bright-field microscopy the dominance of the high-resolution elastic component is evident only for small underfocus values, but at the larger underfocus values the inelastic image is relevant.
12 citations
TL;DR: The rediffused electrons form the largest number of electrons emitted from a sample bombarded by electrons in the 20 kV energy range as discussed by the authors, and they are the only electrons that can be found to be redifused.
Abstract: The rediffused electrons form the largest number of electrons emitted from a sample bombarded by electrons in the 20 kV energy range.
TL;DR: In this paper, a method for two-dimensional deconvolution is applied in the correction of a computer-generated transmission electron microscope image of a planar object subjected to lens aberrations (spherical aberration and defocusing), in an attempt to assess the viability of resolving molecular structure in the transmission electron microsc.
Abstract: A method for two-dimensional deconvolution is applied in the correction of a computer-generated transmission electron microscope image of a planar object subjected to lens aberrations (spherical aberration and defocusing), in an attempt to assess the viability of resolving molecular structure in the transmission electron microscope. The object considered is a phthalocyanine molecule examined in bright-field microscopy at incident electron energies of 100 and 200 keV, and for different objective lens defocus values. The results are presented in the form of intensity profiles along the y axis for the aberrated image in the absence of experimental error, and an image affected by (i) random error and (ii) sinusoidal error of varying frequency. The effect on the deconvoluted result of using an incorrect defocus value in the deconvolution procedure is examined. The results derived for the object structure differ in detail from the known molecular shape; these differences arise from the necessary assumption of a linear relationship between the image intensity and the object structure. Further, the effects of the lens aberrations extend out to 5 nm from the centre of the molecule, and the present results were restricted to a radius of 1?5 nm from this centre.
TL;DR: This chapter presents the advantages of the scanning electron microscope; summarizes the principles of scanning electron microscopy; briefly describes the methods for specimen preparation; and outlines some of its applications in microbiology.
Abstract: Publisher Summary This chapter presents the advantages of the scanning electron microscope; summarizes the principles of scanning electron microscopy; briefly describes the methods for specimen preparation; and outlines some of its applications in microbiology. The concept of scanning electron microscopy dates back to that of conventional transmission electron microscopy. The initial patent application for a scanning electron microscope was made in 1927 but the first instrument was not built until 1938. The scanning electron microscope has several features that render it advantageous for various kinds of microscopic observation. Information can be obtained from different electron beam-induced signals that include (a) secondary electrons, (b) back-scattered electrons, (c) X-rays, (d) visible light or infrared energy, and (e) currents from semiconductors. Thus, it is possible to gather information on the chemical composition and electrical properties of biological materials as well as interaction of such materials with specific stains. The scanning electron microscope also affords image production comparable to light, ultraviolet, fluorescence, and X-ray microscopes. Moreover, it has great depth of focus and produces images with three-dimensional quality. Specimen preparation is usually reduced to a minimum and sometimes, does not require chemical fixation or physical pretreatment. Consequently, biological material can be viewed directly as it actually is, only magnified.
TL;DR: It is the conclusion of the authors that sections and films should be mounted on the dull or matte surface of Athene-type specimen grids.
Abstract: Mounting of support films and sections for transmission electron microscopy has been examined with the scanning electron microscope. Experiments have been designed to test the adherence of support films to polished and matte surfaces of specimen grids. It is the conclusion of the authors that sections and films should be mounted on the dull or matte surface of Athene-type specimen grids.
TL;DR: In this paper, a method for the production of disc specimens for transmission electron microscopy which involves the dissolution of the materials around a protected disc-shaped area of suitable size is described.
Abstract: A method has been devised for the production of disc specimens for transmission electron microscopy which involves the dissolution of the materials around a protected disc-shaped area of suitable size. The apparatus involved and the procedures required are relatively simple and the method can be applied to numerous metals, being rapid, consistent and free of deformation.
01 Aug 1973
TL;DR: In this article, the authors present an example of computer image enhancement of a weak-beam micrograph using a narrowing of the individual dislocation image widths, which results in an increase in the resolution of closely spaced dislocations.
Abstract: In order to perform quantitative image-contrast analysis of low-contrast
electron micrographs one must first increase the signal to noise ratio. As an example, consider the weak-beam method ' of
imaging defects by transmission electron microscopy. In this technique
an increase in the resolution of closely spaced dislocations is obtained
through a narrowing of the individual dislocation image widths. However,
this reduction in image width is accompanied by a corresponding decrease
in the signal to noise ratio, which in many instances renders quantitative
image-contrast analysis impractical. In this note we present an example
of the computer image enhancement of a weak-beam micrograph.
TL;DR: In this article, a simple procedure was described that allows high-resolution transmission electron microscopy of strongly ferromagnetic specimens in the Philips EM 200 and the electromagnetic beam tilt device of the microscope was used to compensate for the interaction of the electron beam with the magnetization of the specimen.
Abstract: A simple procedure is described that allows high‐resolution transmission electron microscopy of strongly ferromagnetic specimens in the Philips EM 200. The electromagnetic beam tilt device of the microscope is used to compensate for the interaction of the electron beam with the magnetization of the specimen. Using this method, even relatively massive magnetic samples can be examined.