Electron microscopic studies of internal gettering of nickel in silicon

1990 ◽  
Vol 5 (5) ◽  
pp. 1013-1016 ◽  
Author(s):  
P.K. Sinha ◽  
W.S. Glaunsinger
Keyword(s):  
Electron Microscopy ◽  
Front Surface ◽  
High Resolution Electron Microscopy ◽  
Nickel Silicide ◽  
Back Surface ◽  
Electron Microscopic ◽  
Resolution Electron ◽  
Microscopic Studies ◽  
Argon Ions ◽  
Electron Microdiffraction

The internal gettering of nickel in (100) silicon wafers implanted with 2.5 ⊠ 1015 argon-ions/cm2 at 280 keV has been studied by electron microscopy. Nickel deposited on the back surface is gettered by forming a discontinuous layer of nickel silicide, NiSi2, in the argon-implanted region near the front surface. Electron microdiffraction and high-resolution electron microscopy indicate that the layers of nickel silicide probably grow epitaxially on the undamaged silicon surrounding the silicide.

scholarly journals HIGH-RESOLUTION ELECTRON MICROSCOPIC ANALYSIS OF THE AMYLOID FIBRIL

1967 ◽  
Vol 33 (3) ◽  
pp. 679-708 ◽  
Author(s):  
Tsuranobu Shirahama ◽  
Alan S. Cohen
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Amyloid Fibrils ◽  
Amyloid Fibril ◽  
Microscopic Analysis ◽  
High Resolution Electron Microscopy ◽  
Ultrastructural Organization ◽  
Electron Microscopic ◽  
Tissue Sections ◽  
Resolution Electron

The ultrastructural organization of the fibrous component of amyloid has been analyzed by means of high resolution electron microscopy of negatively stained isolated amyloid fibrils and of positively stained amyloid fibrils in thin tissue sections. It was found that a number of subunits could be resolved according to their dimensions. The following structural organization is proposed. The amyloid fibril, the fibrous component of amyloid as seen in electron microscopy of thin tissue sections, consists of a number of filaments aggregated side-by-side. These amyloid filaments are approximately 75–80 A in diameter and consist of five (or less likely six) subunits (amyloid protofibrils) which are arranged parallel to each other, longitudinal or slightly oblique to the long axis of the filament. The filament has often seemed to disperse into several longitudinal rows. The amyloid protofibril is about 25–35 A wide and appears to consist of two or three subunit strands helically arranged with a 35–50-A repeat (or, less likely, is composed of globular subunits aggregated end-to-end). These amyloid subprotofibrillar strands measure approximately 10–15 A in diameter.

Trimethyllead Acetate as a DNA Backbone Stain for Electron Microscopy

1975 ◽  
Vol 33 ◽  
pp. 624-625
Author(s):  
A. Kosiara ◽  
K. Douglass ◽  
M. Beer
Keyword(s):  
Electron Microscopy ◽  
Equilibrium Dialysis ◽  
Equilibrium Constants ◽  
High Resolution Electron Microscopy ◽  
Electron Microscopic ◽  
Phosphate Backbone ◽  
Resolution Electron ◽  
Dna Backbone ◽  
Experimental Values ◽  
Image Position

In the process of developing electron microscopic techniques for sequencing DNA it has become clear that in addition to selective heavy metal labeling of the bases it will be necessary to label the phosphate backbone as well. We have studied the suitability of trimethyllead acetate as a backbone label for high resolution electron microscopy of DNA.The binding of the trimethyllead ion to acetate was studied by acid-base titration and DC conductivity, while the binding to DNA was determined by equilibrium dialysis. Most measurements were done in solutions of low ionic strength, approximating the conditions for staining reactions.Defining the equilibrium constants,and choosing Ka and Kb to fit the titration curve we obtain the experimental values given in Table I.The conductivity of PbMe3Ac was measured in water and in 50%, dioxane. The data were analyzed according to the method of Fuoss and the results are given in Table I.

High Resolution Electron Microscopy of thin Co-Cr films

1990 ◽  
Vol 48 (4) ◽  
pp. 786-787
Author(s):  
B. G. Demczyk
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Direct Evidence ◽  
High Resolution Electron Microscopy ◽  
Film Plane ◽  
Perpendicular Recording ◽  
Fine Grained ◽  
Resolution Electron ◽  
Columnar Grains ◽  
Electron Microdiffraction

Co-Cr thin films have been studied extensively as leading candidates for perpendicular recording media. The development of microstructure in this system has been reported by a number of investigators. These studies have revealed a general growth scenario in which a fine grained, randomly oriented "transition layer" forms first, followed by the development of columnar grains having their hcp c axes textured normal to the film plane. However, it has been found that such columns are not present in very thin (∽10 nm) layers. Also, it has been inferred from electron microdiffraction studies that both c and a axis texturing occurs in these same films. However, direct evidence for this texturing is still needed. In this work, high resolution electron microscopy (HREM) has been employed to examine very thin (5-10 nm) Co-Cr layers.

Microstructure of supported platinum-gold bimetallic catalysts

1989 ◽  
Vol 47 ◽  
pp. 260-261
Author(s):  
Amit Sachdev
Keyword(s):  
Bimetallic Catalysts ◽  
Active Sites ◽  
Supported Catalysts ◽  
High Resolution Electron Microscopy ◽  
Electron Microscopic ◽  
Adsorption Sites ◽  
Small Probe ◽  
Resolution Electron ◽  
Partially Miscible ◽  
Microscopic Studies

Bimetallic supported catalysts comprised of a Group VIII metal, such as platinum, and a Group IB element, like gold, have been found to possess superior selectivities towards the formation of desired products as well as a decreased rate of deactivation. The correlation between the microstructure of these materials with their catalytic behavior is essential in understanding the reaction kinetics. Previous electron microscopic studies on bimetallic catalysts have primarily concentrated upon systems whose metallic components are immiscible in the bulk. In this project, the partially miscible Pt-Au and the completely miscible Pt-Sn systems were investigated. In Pt-Au catalysts the catalytically inactive Au component is known to dilute the ensembles of the Pt active sites, thereby favoring the production of compounds whose intermediates require fewer adsorption sites. The typical metal particle size distribution in Pt-Au catalysts ranges from 0.5 nm to 40 nm. The microanalysis of particles larger than 10 nm can be easily done by means of small probe microdiffraction and EDX. The structure and composition of the smaller particles, where most of the interesting catalysis takes place, was determined from the structure images of high resolution electron microscopy.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

One Million Direct Magnification Microscopy

1971 ◽  
Vol 29 ◽  
pp. 166-167
Author(s):  
J. A. Hugo ◽  
V. A. Phillips
Keyword(s):  
Electron Microscopy ◽  
High Resolution Electron Microscopy ◽  
Illumination Level ◽  
Level Of Detail ◽  
Photographic Emulsion ◽  
Low Contrast ◽  
Fluorescent Screen ◽  
Resolution Electron ◽  
Lattice Images ◽  
Electron Microscopes

A continuing problem in high resolution electron microscopy is that the level of detail visible to the microscopist while he is taking a picture is inferior to that obtainable by the microscope, readily readable on a photographic emulsion and visible in an enlargement made from the plate. Line resolutions, of 2Å or better are now achievable with top of the line 100kv microscopes. Taking the resolution of the human eye as 0.2mm, this indicates a need for a direct viewing magnification of at least one million. However, 0.2mm refers to optimum viewing conditions in daylight or the equivalent, and certainly does not apply to a (colored) image of low contrast and illumination level viewed on a fluorescent screen through a glass window by the dark-adapted eye. Experience indicates that an additional factor of 5 to 10 magnification is needed in order to view lattice images with line spacings of 2 to 4Å. Fortunately this is provided by the normal viewing telescope supplied with most electron microscopes.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

Electron microscopy of rabbit FC crystals

1983 ◽  
Vol 41 ◽  
pp. 730-731
Author(s):  
Robert A. Grant ◽  
Laura L. Degn ◽  
Wah Chiu ◽  
John Robinson
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Molecular Replacement ◽  
X Ray ◽  
X Ray Crystallography ◽  
Resolution Electron ◽  
Replacement Technique ◽  
Hydrated Crystal ◽  
Molecular Structure Analysis

Proteolytic digestion of the immunoglobulin IgG with papain cleaves the molecule into an antigen binding fragment, Fab, and a compliment binding fragment, Fc. Structures of intact immunoglobulin, Fab and Fc from various sources have been solved by X-ray crystallography. Rabbit Fc can be crystallized as thin platelets suitable for high resolution electron microscopy. The structure of rabbit Fc can be expected to be similar to the known structure of human Fc, making it an ideal specimen for comparing the X-ray and electron crystallographic techniques and for the application of the molecular replacement technique to electron crystallography. Thin protein crystals embedded in ice diffract to high resolution. A low resolution image of a frozen, hydrated crystal can be expected to have a better contrast than a glucose embedded crystal due to the larger density difference between protein and ice compared to protein and glucose. For these reasons we are using an ice embedding technique to prepare the rabbit Fc crystals for molecular structure analysis by electron microscopy.

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