Design and applications of a post-column imaging filter

1992 ◽  
Vol 50 (2) ◽  
pp. 1192-1193
Author(s):  
O.L. Krivanek ◽  
A.J. Gubbens ◽  
N. Dellby ◽  
C.E. Meyer
Keyword(s):  
Electron Beam ◽  
Diffraction Pattern ◽  
Ccd Camera ◽  
Slit Width ◽  
Normal Operation ◽  
Entrance Aperture ◽  
Principal Parts

We have designed and built an imaging filter which can can be attached to most standard TEMs, and is capable of operating at primary energies of up to 400 keV. The column-mounted hardware consists of 8 principal parts (Fig. 1): 1) entrance aperture, 2) pre-prism focussing and alignment coils, 3) magnetic prism, 4) spectrum-magnifying quadrupoles, 5) pneumatically retractable energy-selecting slit, 6) quadrupole-sextupole imaging assembly, 7) pneumatically retractable TV-rate CCD camera, and 8) slowscan CCD (SSC) camera. In normal operation, the entrance aperture selects a part of an image (or a diffraction pattern) that is projected by the microscope into the viewing chamber, and a doubly-focused spectrum is produced at the energy selecting slit (with a dispersion of 6 μm / eV at 200 keV). The slit width is piezoelectrically adjustable, and the whole slit assembly can be withdrawn pneumatically from the electron beam. Similar to the TEM column which can either produce an image or a diffraction pattern, the post-slit quadrupole-sextupole assembly can produce either a focussed spectrum at the SSC (or the TV), or a magnified image of the specimen.

Über eine Anordnung zur Filterung von Elektroneninterferenzen

1962 ◽  
Vol 17 (12) ◽  
pp. 1066-1070 ◽  
Author(s):  
Karl Brack
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Electron Diffraction Pattern ◽  
Deflection Angle ◽  
Angular Width ◽  
Maximum Deflection ◽  
Entrance Aperture ◽  
Deflection System

The following paper describes a device in order to separate the inelastically scattered electrons from the electron diffraction pattern. By means of an electric and magnetic deflecting system the diffraction pattern is swept across the small entrance aperture of a filter lens. In this way an electron beam with a small divergence passes the filter lens. Behind the filter lens the electron beam is deflected by another deflection system, which is synchronised with the first. So one gets a diffraction pattern, the angular width of which is determined by the maximum deflection angle of the deflecting system. If the retarding potential of the filter lens is high enough, one can photograph the filtered electron diffraction pattern. By reducing the retarding potential one gets unfiltered diagrams.

Electron holography of p-n junctions

1996 ◽  
Vol 54 ◽  
pp. 974-975
Author(s):  
B.G. Frost ◽  
D.C. Joy ◽  
L.F. Allard ◽  
E. Voelkl
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Field Emission ◽  
Ccd Camera ◽  
Image Plane ◽  
Reference Wave ◽  
Field Of View ◽  
Control Mode ◽  
Objective Lens ◽  
Electron Holography

A wide holographic field of view (up to 15 μm in the Hitachi-HF2000) is achieved in a TEM by switching off the objective lens and imaging the sample by the first intermediate lens. Fig.1 shows the corresponding ray diagram for low magnification image plane off-axis holography. A coherent electron beam modulated by the sample in its amplitude and its phase is superimposed on a plane reference wave by a negatively biased Möllenstedt-type biprism.Our holograms are acquired utilizing a Hitachi HF-2000 field emission electron microscope at 200 kV. Essential for holography are a field emission gun and an electron biprism. At low magnification, the excitation of each lens must be appropriately adjusted by the free lens control mode of the microscope. The holograms are acquired by a 1024 by 1024 slow-scan CCD-camera and processed by the “Holoworks” software. The hologram fringes indicate positively and negatively charged areas in a sample by the direction of the fringe bending (Fig.2).

scholarly journals A novel nondestructive diagnostic method for mega-electron-volt ultrafast electron diffraction

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Xi Yang ◽  
Junjie Li ◽  
Mikhail Fedurin ◽  
Victor Smaluk ◽  
Lihua Yu ◽  
...  
Keyword(s):  
Electron Beam ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Real Time ◽  
Beam Energy ◽  
Energy Spread ◽  
Radial Mode ◽  
Electron Beam Energy ◽  
Ultrafast Electron Diffraction ◽  
Electron Volt

AbstractA real-time, nondestructive, Bragg-diffracted electron beam energy, energy-spread and spatial-pointing jitter monitor is experimentally verified by encoding the electron beam energy and spatial-pointing jitter information into the mega-electron-volt ultrafast electron diffraction pattern. The shot-to-shot fluctuation of the diffraction pattern is then decomposed to two basic modes, i.e., the distance between the Bragg peaks as well as its variation (radial mode) and the overall lateral shift of the whole pattern (drift mode). Since these two modes are completely decoupled, the Bragg-diffraction method can simultaneously measure the shot-to-shot energy fluctuation from the radial mode with 2·10−4 precision and spatial-pointing jitter from the drift mode having wide measurement span covering energy jitter range from 10−4 to 10−1. The key advantage of this method is that it allows us to extract the electron beam energy spread concurrently with the ongoing experiment and enables online optimization of the electron beam especially for future high charge single-shot ultrafast electron diffraction (UED) and ultrafast electron microscopy (UEM) experiments. Furthermore, real-time energy measurement enables the filtering process to remove off-energy shots, improving the resolution of time-resolved UED. As a result, this method can be applied to the entire UED user community, beyond the traditional electron beam diagnostics of accelerators used by accelerator physicists.

The Deflection of Electron Reams Traversing A Crystal Face

1985 ◽  
Vol 43 ◽  
pp. 62-63
Author(s):  
J.M. Cowley ◽  
Z.L. Kang
Keyword(s):  
Electron Beam ◽  
Diffraction Pattern ◽  
Potential Field ◽  
Order Term ◽  
Image Force ◽  
Second Order ◽  
Crystal Face ◽  
The Face ◽  
Small X ◽  
Theoretical Results

A serious discrepancy exists between the experimental and theoretical results on the deflection of an electron beam passing parallel to, and just outside, the flat face of a crystal. In a previous paper we reported that for a beam of diameter about 15Å traversing the face of a small gold crystal within a distance of 20Å or less, the central spot of the diffraction pattern is seen to be displaced through angles of up to 10-2 radians. Similar observations had been made for MgO crystals. Rough agreement with the observations could be obtained by assuming the beam to be deflected by a potential field extending into the vacuum and having the formwhere ϕo is the inner potential of the crystal and A, B and C are positive constants. This model for the potential field is based on the assumption of an image force modified for small x by a second order term.

A high-resolution, wide-field, optically coupled, digital CCD camera for the JEOL 4000-EX intermediate-voltage electron microscope

1992 ◽  
Vol 50 (2) ◽  
pp. 960-961
Author(s):  
Edward Horn ◽  
Gregory J. Metzger ◽  
Francis T. Ashton ◽  
Lee D. Peachey
Keyword(s):  
Electron Microscope ◽  
Ccd Camera ◽  
Normal Operation ◽  
Design Parameters ◽  
Wide Field ◽  
Good Resolution ◽  
Image Size ◽  
Camera System ◽  
Voltage Electron ◽  
Viewing Screen

We have designed and constructed a camera system for acquisition of digital images directly from a JEOL 4000-EX 400 kV transmission electron microscope. Our major goal was the ablity to sample and test images for suitability for various forms of image processing and analysis during a session on the microscope, rather than after processing and digitizing films, so that adjustments could be made while the specimens were still in place. Our design parameters were 1) good resolution, in terms of pixels in the image, 2) wide field, so low magnification images could be obtained, 3) no interference with normal operation of the microscope, including the film camera, and 4) minimal modification of the microscope.Cameras positioned below the film camera have narrow fields of view because of increase in image size below the film camera and the small size of CCD targets relative to film. We chose a position above the microscope's fluorescent viewing screen, where there is a convenient port on the 4000-EX, and achieved a field width approximately equal to that on film.

Low-dose high-resolution EM of zeolite materials with slow A scan CCD camera

1992 ◽  
Vol 50 (1) ◽  
pp. 302-303
Author(s):  
M. Pan ◽  
P.A. Crozier
Keyword(s):  
Image Processing ◽  
Electron Beam ◽  
High Resolution ◽  
Low Dose ◽  
Ccd Camera ◽  
Low Noise ◽  
Great Sensitivity ◽  
Recording Device ◽  
High Resolution Structure ◽  
Resolution Structure

Zeolite materials are widely used as an important type of catalyst in oil industry. Their catalytic properties and performance are closely related to their unique structures. Use of high resolution electron microscopy (HREM) to characterize structures of zeolite materials has been limited mainly due to the great sensitivity of the framework structures to electron beam irradiation used in the observation. With the recent development in solid state electronics, a new type of image recording device, known as a charge-coupled-device (CCD), has been made possible. Among many of its superior properties, it has been found that the very low noise level present in a slow scan CCD camera offers the possibility of recording high resolution structure images of zeolite materials with very low electron beam dose. The digital storage of CCD images allows on-line image processing to be performed at the microscope, thus making the recording of low dose electron microscope images more efficient. Image processing was also found to be essential in extracting high resolution structure information contained in the noisy low dose HREM CCD images.

Automation in electron diffraction analysis

1995 ◽  
Vol 53 ◽  
pp. 170-171
Author(s):  
J. M. Zuo
Keyword(s):  
Electron Diffraction ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Ccd Camera ◽  
Lattice Parameter ◽  
Electron Diffraction Analysis ◽  
Full Automation ◽  
Imaging Plates ◽  
Complex Crystal

Automated lattice parameter measurement and orientation analysis are often needed in the characterization of microstructures using electron diffraction, and is made possible with increasingly popular use of slow scan CCD camera and imaging plates. Both of these two detectors are largely linear and digital. Typical electron diffraction analysis has three steps: 1) diffraction pattern measurement, 2) diffraction pattern indexing and 3) solution. Full automation in all these three steps is desired, however, may be hard to achieve especially for complex crystal structures. The importance of automation in each of these steps depends on the type of analysis and the number of analysis needed. Full automation is necessary in the type of applications where the same analysis is repeated many times, such as in texture analysis. In table 1, various applications of electron diffraction and automation needed are listed.There are two types of approach to the automatic indexing. The commonly used method is to matching a calculated list of g's with the measured ones.

Observations on Evaporated Tantalum Films

1969 ◽  
Vol 27 ◽  
pp. 114-115
Author(s):  
F. M. Berting ◽  
K. R. Lawless
Keyword(s):  
Electron Beam ◽  
Single Crystal ◽  
Diffraction Pattern ◽  
High Purity ◽  
Electron Beam Evaporation ◽  
Vacuum System ◽  
Tantalum Films

High purity tantalum was vacuum deposited by electron beam evaporation onto polished {100} surfaces of single crystal MgO heated to temperatures between 700°C and 800°C. An ion pumped vacuum system was used, giving a vacuum of from 3·10-6 to 5·10-7 torr during actual deposition.The diffraction pattern from these Ta films (Figure 1) is very similar to that observed by Hutchinson and Olsen for one-quarter hour annealed Nb films.

Interpretation of the Nano-Electron-Diffraction Patterns along the Five-Fold Axis of Decahedral Gold Nanoparticles

2011 ◽  
Vol 17 (2) ◽  
pp. 279-283 ◽  
Author(s):  
L.D. Romeu ◽  
J. Reyes-Gasga
Keyword(s):  
Gold Nanoparticles ◽  
Electron Beam ◽  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Rotational Symmetry ◽  
Fold Axis ◽  
Double Refraction ◽  
Dynamical Diffraction ◽  
Refraction Effect ◽  
Diffraction Patterns

AbstractThe transition from 10-fold to 5-fold symmetry was observed during the analysis of nanodiffraction patterns of a gold decahedral multiple twinned nanoparticle of 15 nm in diameter. The analysis shows that as the convergence of the beam is increased, the rotational symmetry of the diffraction pattern shifts from 10- to 5-fold. The 10-fold symmetry predicted by Friedel's law is lost by the asymmetric shift of the diffraction spots, an effect that becomes more noticeable as the electron beam convergence increases. Dynamical and kinematical diffraction calculations indicate this decrease in symmetry is the result of a double refraction effect coupled with the variation of the dynamical diffraction conditions arising from a varying electron beam convergence.

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.

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