Energy Filtering in Electron Microscopy and Electron Diffraction

1973 ◽  
Vol 31 ◽  
pp. 282-283
Author(s):  
R. Castaing
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Energy Loss ◽  
Energy Filtering ◽  
Electrostatic Mirror

Energy filtering has proved to be a most valuable tool in electron microscopy. By the simple introduction of a dispersive device in the column of the electron microscope, it is possible to select quite easily, for the production of the image, those of the electrons which have suffered, when crossing the specimen, a given amount of energy loss. A simple filtering device, comprising two 90° magnetic deflections separated by a reflection on an electrostatic mirror, makes possible to select a 1 eV energy bandwidth in the energy loss spectrum of 100 keV electrons without disturbing the quality of the image ; the chosen energy loss may go from zero (quasi-elastic images) up to several hundredths of electron-volts.

Data Acquisition and Handling Unit for a Quantitative Use of Electron Energy Loss Spectroscopy

1977 ◽  
Vol 35 ◽  
pp. 232-233 ◽  
Author(s):  
P. Trebbia ◽  
P. Ballongue ◽  
C. Colliex
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Single Channel ◽  
Detection System ◽  
Surface Barrier ◽  
Solid State Detector ◽  
Electrostatic Mirror ◽  
Electron Energy Loss

An effective use of electron energy loss spectroscopy for chemical characterization of selected areas in the electron microscope can only be achieved with the development of quantitative measurements capabilities.The experimental assembly, which is sketched in Fig.l, has therefore been carried out. It comprises four main elements.The analytical transmission electron microscope is a conventional microscope fitted with a Castaing and Henry dispersive unit (magnetic prism and electrostatic mirror). Recent modifications include the improvement of the vacuum in the specimen chamber (below 10-6 torr) and the adaptation of a new electrostatic mirror.The detection system, similar to the one described by Hermann et al (1), is located in a separate chamber below the fluorescent screen which visualizes the energy loss spectrum. Variable apertures select the electrons, which have lost an energy AE within an energy window smaller than 1 eV, in front of a surface barrier solid state detector RTC BPY 52 100 S.Q. The saw tooth signal delivered by a charge sensitive preamplifier (decay time of 5.10-5 S) is amplified, shaped into a gaussian profile through an active filter and counted by a single channel analyser.

Dynamical Scattering in Crystalline Biological Specimens. I. Criteria of Validity for Scattering Approximations

1975 ◽  
Vol 33 ◽  
pp. 192-193
Author(s):  
Robert M. Glaeser ◽  
Bing K. Jap
Keyword(s):  
Biological Sciences ◽  
Electron Microscopy ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Born Approximation ◽  
Materials Science ◽  
Image Data ◽  
Dynamical Effect ◽  
Crystallographic Structure ◽  
Electron Microscope Image

The dynamical scattering effect, which can be described as the failure of the first Born approximation, is perhaps the most important factor that has prevented the widespread use of electron diffraction intensities for crystallographic structure determination. It would seem to be quite certain that dynamical effects will also interfere with structure analysis based upon electron microscope image data, whenever the dynamical effect seriously perturbs the diffracted wave. While it is normally taken for granted that the dynamical effect must be taken into consideration in materials science applications of electron microscopy, very little attention has been given to this problem in the biological sciences.

The Current Situation in Chemical Stabilization of Biological Materials

1972 ◽  
Vol 30 ◽  
pp. 132-133
Author(s):  
John H. Luft
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Osmium Tetroxide ◽  
Molecular Level ◽  
Cross Linking ◽  
Chemical Stabilization ◽  
Specimen Preparation ◽  
Sufficient Condition ◽  
Radio Telescopes

With information processing devices such as radio telescopes, microscopes or hi-fi systems, the quality of the output often is limited by distortion or noise introduced at the input stage of the device. This analogy can be extended usefully to specimen preparation for the electron microscope; fixation, which initiates the processing sequence, is the single most important step and, unfortunately, is the least well understood. Although there is an abundance of fixation mixtures recommended in the light microscopy literature, osmium tetroxide and glutaraldehyde are favored for electron microscopy. These fixatives react vigorously with proteins at the molecular level. There is clear evidence for the cross-linking of proteins both by osmium tetroxide and glutaraldehyde and cross-linking may be a necessary if not sufficient condition to define fixatives as a class.

Characterization of submicrometer fluid Inclusions in minerals by Analytical/Transmission Electron Microscopy and electron diffraction

1990 ◽  
Vol 48 (4) ◽  
pp. 424-424
Author(s):  
George Guthrie ◽  
David Veblen
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Electron Diffraction ◽  
Light Microscopy ◽  
Fluid Inclusions ◽  
Energy Dispersive Spectrometer ◽  
Analytical Transmission Electron Microscopy ◽  
Transmission Electron

The nature of a geologic fluid can often be inferred from fluid-filled cavities (generally <100 μm in size) that are trapped during the growth of a mineral. A variety of techniques enables the fluids and daughter crystals (any solid precipitated from the trapped fluid) to be identified from cavities greater than a few micrometers. Many minerals, however, contain fluid inclusions smaller than a micrometer. Though inclusions this small are difficult or impossible to study by conventional techniques, they are ideally suited for study by analytical/ transmission electron microscopy (A/TEM) and electron diffraction. We have used this technique to study fluid inclusions and daughter crystals in diamond and feldspar.Inclusion-rich samples of diamond and feldspar were ion-thinned to electron transparency and examined with a Philips 420T electron microscope (120 keV) equipped with an EDAX beryllium-windowed energy dispersive spectrometer. Thin edges of the sample were perforated in areas that appeared in light microscopy to be populated densely with inclusions. In a few cases, the perforations were bound polygonal sides to which crystals (structurally and compositionally different from the host mineral) were attached (Figure 1).

Analysis of Diffraction Contrast as A Function of Energy Loss in Energy Filtering Transmission Electron Microscope (EFTEM) Imaging and Possible Implications on High-Resolution Compositional Mapping

1999 ◽  
Vol 5 (S2) ◽  
pp. 620-621
Author(s):  
K.T. Moore ◽  
J.M. Howe
Keyword(s):  
Electron Microscope ◽  
Energy Loss ◽  
Electron Energy ◽  
Transmission Electron Microscope ◽  
Diffraction Contrast ◽  
Energy Filtering ◽  
Background Removal ◽  
Transmission Electron ◽  
Important Relationship ◽  
Electron Energy Loss

The dependence of diffraction contrast on electron energy loss is an important relationship that needs to be understood because of its potential effect on energy-filtering transmission electron microscope (EFTEM) images. Often when either a two-window jump-ratio image or a three-window elemental map is produced diffraction contrast is not totally eliminated and contributes to the intensity of the final EFTEM image. Background removal procedures often are unable to completely account for intensity changes due to dynamical effects (i.e., elastic scattering) that occur between images acquired at different energy losses, leaving artifacts in the final EFTEM image.In this study, the relationship between diffraction contrast and electron energy loss was investigated by obtaining EFTEM images of a bend contour in aluminum in 100 eV increments from 0 to 1000 eV (Fig. 1). EFTEM images were acquired a JOEL 2010F FEG TEM with a Gatan imaging filter (GIF) at a microscope magnification of 8 kX using a 1 eV/pixel dispersion, 2X binning (512 x 512) and exposure times ranging from 0.25 s for 0 eV energy loss up to 132 sec for 1000 eV energy loss.

Comparison of Images of Crystalline Specimens by Energy-Filtering TEM at 80 keV and CTEM at 200 keV

1990 ◽  
Vol 48 (2) ◽  
pp. 62-63
Author(s):  
A. Bakenfelder ◽  
L. Reimer ◽  
R. Rennekamp
Keyword(s):  
Electron Microscopy ◽  
Energy Loss ◽  
Chromatic Aberration ◽  
Biological Tissues ◽  
Energy Window ◽  
High Voltage Electron Microscopy ◽  
Energy Filtering ◽  
Voltage Electron ◽  
Transmission Electron ◽  
Crystalline Films

One advantage of energy-filtering electron microscopy (EFEM) is to avoid the chromatic aberration of conventional transmission electron microscopy (CTEM) by the mode of electron spectroscopic imaging (ESI) using either zero-loss filtering of unscattered and elastically scattered electrons or a narrow selected energy window at the most probable loss of the electron-energy-loss spectrum (EELS). Chromatic aberration can also be reduced by high-voltage electron microscopy (HVEM). Comparisons of ESI at 80 keV and CTEM at 200 keV have already been reported for biological tissues. In this contribution we compare the imaging of evaporated crystalline films with ESI at 80 keV in a ZEISS EM902 and with CTEM at 200 keV in a Hitachi H800/NA.Zero-loss filtering at 80 keV can be applied for maximum mass-thicknesses of x=ρt≃150 μg/cm2 where the zero-loss transmission falls below 0.001 and an energy window at the most-probable energy loss can be used below ≃300 μg/cm2. Inelastic scattering preserves the Bragg contrast.

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