High Resolution Electron Microscopy of A Nicl2 – Intercalated Graphite

1982 ◽  
Vol 20 ◽  
Author(s):  
D. Dorignac ◽  
M.J. Lahana ◽  
R. Jagut ◽  
B. Jouffrey ◽  
S. Flandrois ◽  
...  
Keyword(s):  
High Resolution ◽  
Local Structure ◽  
High Resolution Electron Microscopy ◽  
Image Simulation ◽  
Statistical Nature ◽  
Structure Information ◽  
Second Stage ◽  
Intercalated Graphite ◽  
Resolution Electron ◽  
Electron Imaging

ABSTRACTHigh resolution electron imaging supported by computer image simulation has been carried out for a nominal “second–stage” NiCl2 graphite compound. The resulting local structure information underlines the statistical nature of the stage ordering, rarely perfectly regular. It also shows the interpenetration of differently staged regions.

Electron crystallographic determination of the 3-D structure of staurolite at atomic resolution

1991 ◽  
Vol 49 ◽  
pp. 540-541
Author(s):  
Kenneth H. Downing ◽  
Hu Meisheng ◽  
Hans-Rudolf Went ◽  
Michael A. O'Keefe
Keyword(s):  
High Resolution ◽  
Three Dimensional ◽  
High Resolution Electron Microscopy ◽  
Atomic Resolution ◽  
Dimensional Structure ◽  
Structure Information ◽  
Resolution Electron ◽  
Scattering Effects ◽  
High Resolution Images ◽  
Effects Of Radiation

With current advances in electron microscope design, high resolution electron microscopy has become routine, and point resolutions of better than 2Å have been obtained in images of many inorganic crystals. Although this resolution is sufficient to resolve interatomic spacings, interpretation generally requires comparison of experimental images with calculations. Since the images are two-dimensional representations of projections of the full three-dimensional structure, information is invariably lost in the overlapping images of atoms at various heights. The technique of electron crystallography, in which information from several views of a crystal is combined, has been developed to obtain three-dimensional information on proteins. The resolution in images of proteins is severely limited by effects of radiation damage. In principle, atomic-resolution, 3D reconstructions should be obtainable from specimens that are resistant to damage. The most serious problem would appear to be in obtaining high-resolution images from areas that are thin enough that dynamical scattering effects can be ignored.

Combined Experimentaland Theoretical Determination of the Atomic Structure of the (310) Twin in NB

1991 ◽  
Vol 238 ◽  
Author(s):  
Geoffrey H. Campbells ◽  
Wayne E. King ◽  
Stephen M. Foiles ◽  
Peter Gumbsch ◽  
Manfred Rühle
Keyword(s):  
High Resolution ◽  
Theoretical Models ◽  
High Resolution Electron Microscopy ◽  
Interatomic Potentials ◽  
Image Simulation ◽  
Theoretical Determination ◽  
Atomic Structures ◽  
Resolution Electron ◽  
High Resolution Images

ABSTRACTA (310) twin boundary in Nb has been fabricated by diffusion bonding oriented single crystals and characterized using high resolution electron microscopy. Atomic structures for the boundary have been predicted using different interatomic potentials. Comparison of the theoretical models to the high resolution images has been performed through image simulation. On the basis of this comparison, one of the low energy structures predicted by theory can be ruled out.

Characterization of Tilt Boundaries by Ultra High Resolution Electron Microscopy

1984 ◽  
Vol 41 ◽  
Author(s):  
W. Krakow ◽  
J. T. Wetzel ◽  
D. A. Smith ◽  
G. Trafas
Keyword(s):  
High Resolution ◽  
Grain Boundary ◽  
Structural Information ◽  
Theoretical Work ◽  
High Resolution Electron Microscopy ◽  
Point Of View ◽  
Experimental Point ◽  
Structure Information ◽  
Resolution Electron ◽  
Tilt Boundaries

AbstractA high resolution electron microscope study of grain boundary structures in Au thin films has been undertaken from both a theoretical and experimental point of view. The criteria necessary to interpret images of tilt boundaries at the atomic level, which include electron optical and specimen effects, have been considered for both 200kV and the newer 400kV medium voltage microscopes. So far, the theoretical work has concentrated on two different [001] tilt bounda-ries where a resolution of 2.03Å is required to visualize bulk lattice structures on either side of the interface. Both a high angle boundary, (210) σ=5, and a low angle boundary, (910) σ=41, have been considered. Computational results using multislice dynamical diffraction and image simulations of relaxed bounda-ries viewed edge-on and with small amounts of beam and/or specimen inclina-tion have been obtained. It will be shown that some structural information concerning grain boundary dislocations can be observed at 200kV. However, many difficulties occur in the exact identification of the interface structure viewed experimentally for both [001] and [011] boundaries since the resolution required is near the performance limit of a 200kV microscope. The simulated results at 400kV indicate a considerable improvement will be realized in obtain-ing atomic structure information at the interface.

What is the Future for Image Simulation?

1997 ◽  
Vol 3 (S2) ◽  
pp. 1139-1140
Author(s):  
D. Van Dyck
Keyword(s):  
High Resolution ◽  
Atomic Structure ◽  
Structural Information ◽  
High Resolution Electron Microscopy ◽  
Information Channel ◽  
Image Simulation ◽  
Phase Information ◽  
Indirect Approach ◽  
Resolution Electron ◽  
High Resolution Images

The ultimate goal of high resolution electron microscopy is to determine quantitatively the atomic structure of an object. In this respect the electron microscope can be considered as an information channel that carries this information from the object to the observer. High resolution images are then to be considered as data planes from which the structural information has to be extracted.However this structural information is usually hidden in the images and cannot easily be assessed. Therefore, a quantitative approach is required in which all steps in the imaging process are taken into account. Two main approaches have been followed so far in the literature: the indirect approach in which the images are simulated for various plausible trial structures of the object and compared with the experimental images, and the direct approach in which the lost phase information is retrieved using holographic techniques so as to “deblur” the effect of the microscope and to reveal directly the atomic structure of the object.

On-line high resolution image analysis

1988 ◽  
Vol 46 ◽  
pp. 970-971
Author(s):  
F. Huang ◽  
J. P. Zhang ◽  
M. I. Buckett ◽  
L. D. Marks
Keyword(s):  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Image Simulation ◽  
Fully Integrated ◽  
Recursive Filtering ◽  
Practical Applications ◽  
Resolution Electron ◽  
On Line ◽  
Rate Processes ◽  
Set Up

A persistent practical problem in high resolution electron microscopy has been the diffulty to obtain careful, statistical comparisons between experimental and theoretical images. As a rule, practical applications of image simulation have involved either a direct comparison of calculated and experimental images, or a comparison of digitized images from a microdensitometer. Both of these pose substantial impediments to the final goal of HREM, namely R-factor measurements of the agreement between experimental and theoretical images.As a step beyond these approaches, we have recently finished bus-interfacing a framestore device to an Apollo 3000 workstation. The full set-up is shown in Figure 1. The framestore device, an IMAGING 151 set of boards, can perform all the standard video rate processes such as recursive filtering, as well as accumulating a 16 bit image. This device is fully integrated into the Apollo mini-computer, and is set up so that images can be directly transferred to disk within the SEMPER software system.

The Atomic Structure of Mosaïc Grain Boundary Dislocations in GaN Epitaxial Layers

1999 ◽  
Vol 589 ◽  
Author(s):  
V. Potin ◽  
G. Nouet ◽  
P. Ruterana ◽  
R.C. Pond
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Grain Boundary ◽  
Atomic Structure ◽  
High Resolution Electron Microscopy ◽  
Anisotropic Elasticity ◽  
Epitaxial Layers ◽  
Threading Dislocations ◽  
Image Simulation ◽  
Resolution Electron

AbstractThe studied GaN layers are made of mosaYc grains rotated around the c-axis by angles in the range 0-25°. Using high-resolution electron microscopy, anisotropic elasticity calculations and image simulation, we have analyzed the atomic structure of the edge threading dislocations. Here, we present an analysis of the Σ = 7 boundary using circuit mapping in order to define the Burgers vectors of the primary and secondary dislocations. The atomic structure of the primary ones was found to exhibit 5/7 and 8 atom cycles.

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