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High angle annular dark field imaging has been extensively applied to high resolution imaging of crystalline materials. Dislocations have also been imaged using the high angle dark field detector, even when the lattice has not been directly resolved. Diffraction contrast, as employed in transmission electron microscopy analysis of defects, is a possible mechanism for dislocation contrast. Stacking...
A direct scheme has been developed for crystal and surface structure determination. This scheme is based on a partition of the crystal potential V(r) into a known part V 0 (r) and a perturbation δV(r), i.e. V(r)=V 0 (r)+δV(r). The full dynamical electron diffraction theory is used for treating the dynamical electron diffraction by V 0 (r) and perturbation theory is used for...
A previously unnoticed connection between the classical optical theory of a twisted nematic liquid crystal and the two beam dynamical theory of diffraction in the transmission Laue case (as is applied to calculate beam intensities in X-ray, electron and neutron diffraction), has been uncovered. Both physical situations are described by an equation of the form (d/dz)Φ = 2πAΦ, whereA is an Hermitian...
High quality InAlSb/InSb bilayers and superlattices have been grown by magnetron sputter epitaxy and the physical structure has been characterized by transmission electron microscopy. It was found that single layers of InAlSb, whose thicknesses greatly exceeded the equilibrium critical thickness, could be grown coherently on (001) InSb for Al concentrations approaching 13–15%. Also, it was observed...
The imaging of biomolecules in the lensless, field-emission, point-projection shadow-image electron microscope (PPM), operating between 2 and 100 eV, is reviewed. Radiation damage in this instrument is compared with X-ray and electron microscope imaging (or holography). Two regimes are considered for imaging at low voltage—one in which the inelastic mean free path λ I is much larger than the...
Using geometrical optics, we derive analytical expressions for the chromatic- and spherical-aberration point-spread functions (PSF) of an electron lens, taking into account the angular distribution of inelastic scattering and energy distribution of the electrons forming the image. Because the PSF has extended tails, the chromatic limit to point resolution in an energy-selected image is typically a...
The theory for formation of incoherent channelling patterns (ICPs), produced by variations in characteristic X-ray emission in response to a systematic scan in the direction of the incident electron beam for orientations near a zone axis, is extended to account for absorption of X-rays within the specimen. This is achieved by calculating the probability of X-ray generation as a function of depth within...
The kinematic theory of electron scattering is used to estimate the dark-field, weak-beam image contrast of a stacking fault with an associated fault vector which has a component in the direction perpendicular to the plane of the fault. It is shown, using the rigid ion model of the crystal potential, that the average contrast of the image depends on the sign of the diffraction vector. The difference...
Nonradioactive in situ hybridization is a powerful technique for determining levels of mRNA that have accumulated in tissues, and bright-field microscopy has been used extensively to detect signals generated by nonradioactive in situ hybridization. We converted an inverted microscope to a dark-field microscope by equipping it with a handmade ring-slit. When the in situ hybridization pattern in a...
The cytoplasm of Entamoeba is characterized by the presence of a large number of vesicles of different size and shape. Previous electron microscopic studies have not clearly revealed the presence of the endoplasmic reticulum and the Golgi complex. In the present study two approaches were used aimed at the identification of these two structures in trophozoites of Entamoeba moshkovskii and Entamoeba...
The investigation of neurohistological specimens by image analysis has become an important tool in morphological neuroscience. The problems which arise during the processing of these images are non-trivial, especially if a pattern recognition of cells in the imaged tissue is intended. One of the major problems faced concerns the segmentation of structures of interest, whether cells or other histologic...
Aspartate transcarbamylase (ATCase) activity was localized ultracytochemically in the yeast Saccharomyces cerevisiae by precipitation of its reaction product orthophosphate as cerium phosphate. We prefixed yeast cells with ice-cold 1% glutaraldehyde for 30 min which preserved 80% of ATCase activity. Cells were washed and incubated with ATCase substrates (aspartate, carbamyl phosphate) plus cerium...
Ultramicrotomy is a thin sample preparative method for TEM observations. In materials science, it can be used as an alternative method to mechanical polishing and ion-milling for cross-section specimen preparation. This short communication reports results obtained for two different materials: a laser structure based in semiconductor technology (InP/GaInAs) prepared by MBE and a Au-SiFe multilayer...
The purpose of this study was to examine how different incubation times with different concentrations of bovine serum albumin (BSA) affect the amount of non-specific immunogold labeling on epoxy sections and LR-White sections. Immunogold labeling was performed on epoxy sections and LR-White sections of renal tissue with IgG-deposits and fibrin clots, and the antibodies used were anti-IgG and anti-fibrinogen,...
A backscatter Kikuchi diffraction attachment to an SEM enables the convenient investigation of individual grain orientations on bulk surfaces. Their relation to microstructural features gives insight into many aspects of anisotropic materials properties. The formation of backscatter Kikuchi patterns and the experimental set-up for their acquisition are briefly outlined. The interactive and automated...
The accuracy of and detection limits for trace element analysis using the electron and proton microprobes have been compared using glass samples prepared from whole rock standard powders BE-N basalt, AC-E granite and W-2 diabase. The capabilities and advantages and disadvantages of both techniques for trace element analysis have been examined. The effect of varying the kV on the detection limits...
In order to clarify the β → ω phase transformation mechanism in β-titanium alloys, an investigation of the atomic structure of Ti-Mo alloys at early stages of aging was carried out using high resolution electron microscopy (HREM), in situ HREM, and image-processing methods. The initial structure of ω-phase crystals was observed as a line structure of bright spots in the 〈111〉 directions with 0.28...
The energy loss near edge structures of an early transition metal aluminide (TiAl) and late transition metal aluminides (FeAl and NiAl) have been compared with calculations based on band structure techniques. The differences between theory and experiment are discussed in terms of the validity of the single particle approximation. The better agreement between experiment and theory for the late transition...
It is shown how the historical origins of holographic ideas in the field of crystallography inspire a couple of modern applications. One is to the problem structure completion in the X-ray crystallography of macromolecular structures, and the other to the determination of the binding site of atomic adsorbates on surfaces by means of low energy electron diffraction (LEED). In the first example, it...
The three scanning electron microscope diffraction based techniques of electron channelling patterns (ECPs), electron channelling constrast imaging (ECCI), and electron backscatter diffraction (EBSD) are reviewed. The dynamical diffraction theory is used to describe the physics of electron channelling, and hence the constrast observed in ECPs (and EBSD) and ECCI images of dislocations. Models for...
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