Simulating electron microscope diffraction mode with a Macintosh-based program

1993 ◽  
Vol 51 ◽  
pp. 1210-1211
Author(s):  
J. M. Zuo ◽  
H. R. Zhu ◽  
Andrew Spence
Keyword(s):  
Electron Microscope ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Recent Trend ◽  
Control Panel ◽  
Diffraction Mode ◽  
Pointing Device ◽  
Control Devices ◽  
Diffraction Patterns ◽  
Convergent Beam

With the recent trend towards to the quantification of electron diffraction patterns, there is an increasing need for simulating the geometry of convergent beam electron diffraction patterns, and especially the high order Laue zone (HOLZ) lines in such patterns. The simulation program is useful in the way that the simulated and the experimental pattern can be compared, and then the important diffraction parameters such as reflection indices, beam directions and lattice constant could be found and used. Here we describe a Macintosh based program, which simulates electron diffraction pattern in the same way as the operation of electron microscope diffraction mode. The program has a control panel with the ‘scroll bar’ control devices for x and y tilt of specimen stage, x and y deflection of diffraction pattern and camera length (see figure 1). The user can change the simulated diffraction pattern by changing the ‘control devices’ with a pointing device such as a mouse.

Contrast of Kossel Patterns in Electron Diffraction

1974 ◽  
Vol 29 (12) ◽  
pp. 1929-1930b ◽  
Author(s):  
F. Fujimoto ◽  
G. Lehmpfuhl
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Hollow Cone ◽  
Angular Aperture ◽  
Kossel Pattern ◽  
Diffraction Patterns ◽  
Convergent Beam

Electron diffraction patterns from a Si crystal taken with a convergent beam of large angular aperture (Kossel pattern) are compared with the diffraction pattern taken with a hollow cone convergent electron beam. For thin crystals the patterns are complementary. This behaviour is discussed.

scholarly journals Particle size and convergent electron diffraction patterns of triangular prismatic gold nanoparticles

2021 ◽  
Vol 67 (4 Jul-Aug) ◽  
Author(s):  
Clemente Fernando-Marquez ◽  
Gilberto Mondragón-Galicia ◽  
Lourdes Bazán-Díaz ◽  
José Reyes-Gasga
Keyword(s):  
Particle Size ◽  
Gold Nanoparticles ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Stacking Faults ◽  
Au Nanoparticle ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Fcc Structure

Convergent beam diffraction (CBED) patterns of nanoparticles are possible. CBED of triangular prismatic shaped Au nanoparticle with focus on diffraction pattern symmetry and forbidden reflections observed along [111] and [112] zone axes are reported in this work. It is well known that the CBED patterns of nanoparticles of 30 nm or less in size only show bright kinematical discs. The dynamic contrast with Kikuchi and sharp HOLZ lines within the bright discs, as observed in CBED of volumetric materials, is well observed in particles larger of 500 nm in size. In addition, it is shown that the 1/3[422] and 1/2[311] weak forbidden reflections observed in the [111] and [112] electron diffraction patterns of these particles do not modify the symmetry of the CBED patterns, but they disappear as the size of the particle increases. The symmetry of the CBED patterns are always observed in concordance with the space group Fm3m (No. 225) of the Au unit cell. The possible explanations for observing forbidden reflections are the incomplete ABC stacking due to surface termination and the stacking faults in the fcc structure.

A library of convergent-beam electron diffraction patterns

1986 ◽  
Vol 44 ◽  
pp. 688-691
Author(s):  
John F. Mansfield
Keyword(s):  
Electron Diffraction ◽  
Materials Science ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Transmission Electron ◽  
Yield Information ◽  
Analytical Electron ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Electron Energy Loss

One of the most important advancements of the transmission electron microscopy (TEM) in recent years has been the development of the analytical electron microscope (AEM). The microanalytical capabilities of AEMs are based on the three major techniques that have been refined in the last decade or so, namely, Convergent Beam Electron Diffraction (CBED), X-ray Energy Dispersive Spectroscopy (XEDS) and Electron Energy Loss Spectroscopy (EELS). Each of these techniques can yield information on the specimen under study that is not obtainable by any other means. However, it is when they are used in concert that they are most powerful. The application of CBED in materials science is not restricted to microanalysis. However, this is the area where it is most frequently employed. It is used specifically to the identification of the lattice-type, point and space group of phases present within a sample. The addition of chemical/elemental information from XEDS or EELS spectra to the diffraction data usually allows unique identification of a phase.

Merging of electron-diffraction intensities acquired with a slow-scan CCD camera of crotoxin complex crystals to 3.5Å resolution

1994 ◽  
Vol 52 ◽  
pp. 104-105
Author(s):  
Jaap Brink ◽  
Wah Chiu
Keyword(s):  
Electron Diffraction ◽  
Ccd Camera ◽  
Crystal Thickness ◽  
Local Contrast ◽  
Camera Model ◽  
Data Set ◽  
3 Dimensional ◽  
Diffraction Mode ◽  
Diffraction Patterns ◽  
Complex Crystals

Crotoxin complex is the principal neurotoxin of the South American rattlesnake, Crotalus durissus terrificus and has a molecular weight of 24 kDa. The protein is a heterodimer with subunit A assigneda chaperone function. Subunit B carries the lethal activity, which is exerted on both sides ofthe neuro-muscular junction, and which is thought to involve binding to the acetylcholine receptor. Insight in crotoxin complex’ mode of action can be gained from a 3 Å resolution structure obtained by electron crystallography. This abstract communicates our progress in merging the electron diffraction amplitudes into a 3-dimensional (3D) intensity data set close to completion. Since the thickness of crotoxin complex crystals varies from one crystal to the other, we chose to collect tilt series of electron diffraction patterns after determining their thickness. Furthermore, by making use of the symmetry present in these tilt data, intensities collected only from similar crystals will be merged.Suitable crystals of glucose-embedded crotoxin complex were searched for in the defocussed diffraction mode with the goniometer tilted to 55° of higher in a JEOL4000 electron cryo-microscopc operated at 400 kV with the crystals kept at -120°C in a Gatan 626 cryo-holder. The crystal thickness was measured using the local contrast of the crystal relative to the supporting film from search-mode images acquired using a 1024 x 1024 slow-scan CCD camera (model 679, Gatan Inc.).

A program for simulation of changes in diffraction patterns with crystal rotations

1990 ◽  
Vol 48 (1) ◽  
pp. 544-545
Author(s):  
F.C. Mijlhoff ◽  
H.W. Zandbergenl
Keyword(s):  
Electron Microscope ◽  
Reciprocal Lattice ◽  
Extensive Training ◽  
Diffraction Mode ◽  
Diffraction Patterns ◽  
Electron Microscopist

Orientation of crystals for HREM is done in diffraction mode. To do this efficiently thorough knowledge of the electron microscope and the reciprocal lattice of the investigated material is essential. With respect to the electron microscope extensive training is required to obtain the ability to tilt a crystal in the desired orientation. Familiarity with the reciprocal lattice of the investigated materials has to be obtained by tilt experiments on a relatively large number of crystals in the electron microscope. Even for experienced electron microscopists this can be very time consuming.In order to be able to practice tilt experiments without using the electron microscope, a program to simulate the electron microscope in diffraction mode was developed. The inexperienced electron microscopist may use the program to practice tilting of crystals. The experienced microscopist can use the program to familiarize with the reciprocal lattice of materials, which have not been studied by him before.

Determination of hydrogen ordering within the β-RH2+xphase (R= Ho, Y) using electron diffraction techniques

2000 ◽  
Vol 33 (5) ◽  
pp. 1246-1252 ◽  
Author(s):  
Elizabeth J. Grier ◽  
Amanda K. Petford-Long ◽  
Roger C. C. Ward
Keyword(s):  
Electron Diffraction ◽  
Neutron Scattering ◽  
Diffraction Pattern ◽  
Computer Simulations ◽  
Fluorite Structure ◽  
Long Range Order ◽  
Hydrogen Atoms ◽  
Ordered Structures ◽  
Diffraction Patterns

Computer simulations of the electron diffraction patterns along the [\bar{1}10] zone axes of four ordered structures within the β-RH2+xphase, withR= Ho or Y, and 0 ≤x≤ 0.25, have been performed to establish whether or not the hydrogen ordering could be detected using electron diffraction techniques. Ordered structures within otherRH2+x(R= Ce, Tb) systems have been characterized with neutron scattering experiments; however, for HoH(D)2+x, neutron scattering failed to characterize the superstructure, possibly because of the lowxconcentration or lack of long-range order within the crystal. This paper aims to show that electron diffraction could overcome both of these problems. The structures considered were the stoichiometric face-centred cubic (f.c.c.) fluorite structure (x= 0), theD1 structure (x= 0.125), theD1astructure (x= 0.2) and theD022structure (x= 0.25). In the stoichiometric structure, with all hydrogen atoms located on the tetrahedral (t) sites, only the diffraction pattern from the f.c.c. metal lattice was seen; however, for the superstoichiometric structures, with the excess hydrogen atoms ordered on the octahedral (o) sites, extra reflections were visible. All the superstoichiometric structures showed extra reflections at the (001)f.c.c.and (110)f.c.c.type positions, with structureD1 also showing extra peaks at (½ ½ ½)f.c.c.. These reflections are not seen in the simulations at similar hydrogen concentrations with the hydrogen atoms randomly occupying theovacancies.

Using the TEM Condenser Lens to Switch between Image and Diffraction Modes

2013 ◽  
Vol 21 (2) ◽  
pp. 40-40
Author(s):  
Lydia Rivaud
Keyword(s):  
Electron Microscope ◽  
Diffraction Pattern ◽  
Transmission Electron Microscope ◽  
Condenser Lens ◽  
Selected Area Diffraction Pattern ◽  
Transmission Electron ◽  
Set Up ◽  
Convergent Beam ◽  
Beam Diffraction ◽  
Convergent Beam Diffraction

Central to the operation of the transmission electron microscope (TEM) (when used with crystalline samples) is the ability to go back and forth between an image and a diffraction pattern. Although it is quite simple to go from the image to a convergent-beam diffraction pattern or from an image to a selected-area diffraction pattern (and back), I have found it useful to be able to go between image and diffraction pattern even more quickly. In the method described, once the microscope is set up, it is possible to go from image to diffraction pattern and back by turning just one knob. This makes many operations on the microscope much more convenient. It should be made clear that, in this method, neither the image nor the diffraction pattern is “ideal” (details below), but both are good enough for many necessary procedures.

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