Spectroscopy and Imaging With Energy-Filtering Tems: Parameters That Matter

2000 ◽  
Vol 6 (S2) ◽  
pp. 158-159
Author(s):  
G. Kothleitner ◽  
H. A. Brink
Keyword(s):  
Imaging Techniques ◽  
Image Resolution ◽  
Elemental Distribution ◽  
Elemental Mapping ◽  
Core Excitation ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Science Investigations ◽  
Shell Ionization

Spectroscopy and imaging techniques based on electron energy-losses (EELS), which are accessible through energy-filtering transmission electron microscopes (EFTEMs), have proven to be important tools in both materials and life science investigations.The two most widely used techniques on commercially available EFTEMs are elastic imaging and elemental mapping. Elastic imaging enhances image resolution and contrast by extracting the zero-loss signal and eliminating the inelastic background, whereas elemental mapping, which involves signals coming from element-specific inner-shell ionization edges, is employed to form two dimensional elemental distribution images. In both cases relatively large energy windows of a range of 10 to 30eVare typically used to form energy-filtered images with usually low to moderately high magnifications.There is however much more information available in an EELS spectrum, which is contained in the detailed fine structure within 0-20eV of a core excitation edge (ELNES) or in the very low energy-loss up to 5eV.

Convergent-beam electron diffraction at high spatial resolution

1992 ◽  
Vol 50 (2) ◽  
pp. 1152-1153 ◽  
Author(s):  
J W Steeds
Keyword(s):  
Electron Diffraction ◽  
High Temperature Superconductors ◽  
Bloch Wave ◽  
Convergent Beam Electron Diffraction ◽  
Beam Electron ◽  
Energy Filtering ◽  
Small Probe ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Convergent Beam

That the techniques of convergent beam electron diffraction (CBED) are now widely practised is evident, both from the way in which they feature in the sale of new transmission electron microscopes (TEMs) and from the frequency with which the results appear in the literature: new phases of high temperature superconductors is a case in point. The arrival of a new generation of TEMs operating with coherent sources at 200-300kV opens up a number of new possibilities.First, there is the possibility of quantitative work of very high accuracy. The small probe will essentially eliminate thickness or orientation averaging and this, together with efficient energy filtering by a doubly-dispersive electron energy loss spectrometer, will yield results of unsurpassed quality. The Bloch wave formulation of electron diffraction has proved itself an effective and efficient method of interpreting the data. The treatment of absorption in these calculations has recently been improved with the result that <100> HOLZ polarity determinations can now be performed on III-V and II-VI semiconductors.

The use of an energy-filtering electron microscope to reduce chromatic aberration in images of thick biological specimens

1986 ◽  
Vol 44 ◽  
pp. 88-91
Author(s):  
L. D. Peachey ◽  
J. P. Heath ◽  
G. Lamprecht
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Beam ◽  
Cross Section ◽  
Electron Scattering ◽  
Chromatic Aberration ◽  
Image Resolution ◽  
Incident Electron Energy ◽  
Energy Filtering ◽  
Transmission Electron

Biological specimens of cells and tissues generally are considerably thicker than ideal for high resolution transmission electron microscopy. Actual image resolution achieved is limited by chromatic aberration in the image forming electron lenses combined with significant energy loss in the electron beam due to inelastic scattering in the specimen. Increased accelerating voltages (HVEM, IVEM) have been used to reduce the adverse effects of chromatic aberration by decreasing the electron scattering cross-section of the elements in the specimen and by increasing the incident electron energy.

Elemental Mapping of Materials Using Omega Filter and Imaging Plate

2000 ◽  
Vol 6 (S2) ◽  
pp. 216-217
Author(s):  
Y. Ikematsu ◽  
D. Shindo ◽  
T. Oikawa ◽  
M. Kersker
Keyword(s):  
Electron Microscope ◽  
Ccd Camera ◽  
Mapping Technique ◽  
Imaging Plate ◽  
Elemental Distribution ◽  
Elemental Mapping ◽  
Window Method ◽  
Transmission Electron ◽  
Window Technique ◽  
Imaging Plates

Elemental microanalysis has been important in materials characterization, since the elemental distribution strongly affects the property of various materials. A recently developed post-column energy filter coupled with a slow scan CCD camera makes it possible to carry out elemental mapping with a transmission electron microscope. Here, we develop the elemental mapping technique utilizing the omega filter and imaging plates (3760x3000 pixels). Since the data obtained from the imaging plates consist of a large number of pixels, fine and detailed elemental analysis will be expected.Energy-filtered images were obtained by a JEM-2010 electron microscope installed with an omega-type energy filter, and they were recorded on imaging plates (FDL-UR-V:25 μm/pixel). The width of an energy-selecting slit was set to be 20 eV. Elemental maps were obtained from the energy-filtered images using the three window technique. Special care was taken to reduce the image shifts among the three filtered images used in the three-window method.

scholarly journals Ghost imaging with electron microscopy inspired, non-orthogonal phase masks

2021 ◽  
Author(s):  
Akhil Kallepalli ◽  
Daan Stellinga ◽  
Ming-Jie Sun ◽  
Richard Bowman ◽  
Enzo Rotunno ◽  
...  
Keyword(s):  
High Resolution ◽  
Imaging Techniques ◽  
High Energy ◽  
Reconstruction Method ◽  
Ghost Imaging ◽  
Light Modulator ◽  
Transmission Electron ◽  
Resolution Imaging ◽  
Electron Microscopes ◽  
Energy Processes

Abstract Transmission electron microscopes (TEM) achieve high resolution imaging by raster scanning a focused beam of electrons over the sample and measuring the transmission to form an image. While a TEM can achieve a much higher resolution than optical microscopes, they face challenges of damage to samples during the high energy processes involved. Here, we explore the possibility of applying computational ghost imaging techniques adapted from the optical regime to reduce the total, required illumination intensity. The technological lack of the equivalent high-resolution, optical spatial light modulator for electrons means that a different approach needs to be pursued. Using the optical equivalent, we show that a simple six-needle charged device to modulate the illuminating beam, alongside a novel reconstruction method to handle the resulting highly non-orthogonal patterns, is capable of producing images comparable in quality to a raster-scanned approach with much lower peak intensity.

An Integrated Energy-Filtering TEM for The Life Sciences

1996 ◽  
Vol 54 ◽  
pp. 466-467
Author(s):  
A.F. de Jong ◽  
H. Coppoolse ◽  
U. Lücken ◽  
M.K. Kundmann ◽  
A.J. Gubbens ◽  
...  
Keyword(s):  
Low Dose ◽  
Life Sciences ◽  
Ccd Camera ◽  
Cold Trap ◽  
Objective Lens ◽  
Elemental Mapping ◽  
Energy Filtering ◽  
Transmission Electron ◽  
Computer Controlled ◽  
High Degree

Energy-filtered transmission electron microscopy (EFTEM) has many uses in life sciences1. These include improved contrast for imaging unstained, cryo or thick samples; improved diffraction for electron crystallography, and elemental mapping and analysis. We have developed a new system for biological EFTEM that combines advanced electron-optical performance with a high degree of automation. The system is based on the Philips CM series of microscopes and the Gatan post-column imaging filter (GIF). One combination particulary suited for the life sciences is that of the CM 120-BioTWIN and the GIF100: the CM120-BioFilter. The CM 120-BioTWIN is equipped with a high-contrast objective lens for biological samples. Its specially designed cold-trap, together with low-dose software, supports full cryo-microscopy. The GIF 100 is corrected for second-order aberrations in both images and spectra. It produces images that are isochromatic to within 1.5 eV at 120 keV and distorted by less than 2% over lk x lk pixels. All the elements of the filter are computer controlled. Images and spectra are detected by a TV camera or a multi-scan CCD camera, both of which are incorporated in the filter. All filter and camera functions are controlled from Digital Micrograph running on an Apple Power Macintosh.

Quantitative Energy-filtering Transmission Electron Microscopy in Materials Science

2000 ◽  
Vol 6 (2) ◽  
pp. 161-172 ◽  
Author(s):  
Werner Grogger ◽  
Ferdinand Hofer ◽  
Peter Warbichler ◽  
Gerald Kothleitner
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Materials Science ◽  
Steel Specimen ◽  
Elemental Distribution ◽  
Secondary Phases ◽  
Energy Filtering ◽  
Transmission Electron ◽  
The Matrix ◽  
Titanate Ceramics

Energy-filtered transmission electron microscopy (EFTEM) can be used to acquire elemental distribution images at high lateral resolution within short acquisition times. In this article, we present an overview of typical problems from materials science which can be preferentially solved by means of EFTEM. In the first example, we show how secondary phases in a steel specimen can be easily detected by recording jump ratio images of the matrix element under rocking beam illumination. Secondly, we describe how elemental maps can be converted into concentration maps. A Ba-Nd-titanate ceramics serves as a typical materials science example exhibiting three different compounds with varying composition.

Quantitative elemental concentrations by energy-filtered imaging

1995 ◽  
Vol 53 ◽  
pp. 268-269 ◽  
Author(s):  
J. Bentley ◽  
E. L. Hall ◽  
E. A. Kenik
Keyword(s):  
Core Loss ◽  
Specimen Thickness ◽  
Elemental Distribution ◽  
Edge Image ◽  
Distribution Maps ◽  
Diffraction Contrast ◽  
Transmission Electron ◽  
Half Angle ◽  
Electron Microscopes ◽  
Thickness Variations

There is widespread interest in elemental distribution maps produced from energy-filtered core-loss images obtained wim commercial imaging energy-filters and slow-scan charge-coupled device (CCD) cameras on transmission electron microscopes (TEMs). Earlier work on the feasibility of mapping solute segregation in stainless steels by energy-filtered imaging confirmed the utility of jump-ratio images (created by division of a post-edge image by a pre-edge one) for rapid assessments of elemental distributions. The effects of diffraction contrast and thickness variations are largely corrected for in such images. However, quantitative compositional information requires the use of net core-loss intensities following subtraction of an extrapolated background. Such core-loss intensities are influenced by diffraction contrast and thickness variations; corrections for these effects may be necessary for a quantitative interpretation. In the present work, energy-filtered images are treated similarly to quantitative electron energy-loss spectrometry (EELS) data. An image showing number of atoms per unit area, nx, is obtained by dividing the core-loss intensity image, Sx(Δ,β), by the low-loss image, J1(Δ,β), obtained with identical energy window Δ and collection half-angle β, and by the partial ionization cross-section, σx(Δ,β). Further normalization by specimen thickness, t, yields an image showing elemental concentration in atoms per unit volume:

Quantitative Energy-Filtering Transmission Electron Microscopy (EFTEM) In Materials Science

1998 ◽  
Vol 4 (S2) ◽  
pp. 128-129
Author(s):  
F. Hofer ◽  
W. Grogger ◽  
P. Warbichler
Keyword(s):  
Materials Science ◽  
Important Application ◽  
Elemental Mapping ◽  
Secondary Phases ◽  
Edge Image ◽  
Energy Filtering ◽  
Window Method ◽  
Transmission Electron ◽  
Elemental Maps

Equipping a transmission electron microscope with an energy-filter offers extraordinary advantages for the characterization of both materials science and biological samples. Besides improvements for TEM imaging and electron diffraction like better contrast and resolution, elemental mapping using inner-shell ionizations has become the main application of EFTEM. Elemental maps with resolution down to 1 nm and elemental sensitivities down to a single monolayer have been reported. Using a Philips CM20 equipped with a Gatan Imaging Filter (GIF) for our experimental work, we acquired elemental maps with the three window method (A.E-1r background extrapolation from two pre-edge windows) and jump ratio images (division of post-edge image by a pre-edge image). One important application of EFTEM is the detection of secondary phases in materials e.g. precipitates and grain boundary phases. For example, fig.la shows the TEM-image of a 10%Cr steel with the secondary phases mostly invisible.

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