Electron spectroscopic imaging and diffraction

1991 ◽  
Vol 49 ◽  
pp. 706-707
Author(s):  
M. Rühle ◽  
J. Mayer ◽  
J.C.H. Spence ◽  
J. Bihr ◽  
W. Probst ◽  
...  
Keyword(s):  
Materials Science ◽  
Electron Spectroscopic Imaging ◽  
Magnetic Filter ◽  
Magnetic Imaging ◽  
Illumination System ◽  
Probe Size ◽  
Diffraction Patterns ◽  
Fritz Haber ◽  
Koehler Illumination ◽  
First Time

A new Zeiss TEM with an imaging Omega filter is a fully digitized, side-entry, 120 kV TEM/STEM instrument for materials science. The machine possesses an Omega magnetic imaging energy filter (see Fig. 1) placed between the third and fourth projector lens. Lanio designed the filter and a prototype was built at the Fritz-Haber-Institut in Berlin, Germany. The imaging magnetic filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient area detection. The energy dispersion at the exit slit (Fig. 1) results in ∼ 1.5 μm/eV which allows imaging with energy windows of ≤ 10 eV. The smallest probe size of the microscope is 1.6 nm and the Koehler illumination system is used for the first time in a TEM. Serial recording of EELS spectra with a resolution < 1 eV is possible. The digital control allows X,Y,Z coordinates and tilt settings to be stored and later recalled.

Two-dimensional omega energy-filtered CBED on the new Zeiss EM912

1991 ◽  
Vol 49 ◽  
pp. 786-787
Author(s):  
J. Mayer ◽  
J.C.H. Spence ◽  
G. Mobus
Keyword(s):  
Materials Science ◽  
Bloch Wave ◽  
Recording Time ◽  
Image Recording ◽  
Magnetic Filter ◽  
Magnetic Imaging ◽  
Refinement Method ◽  
Pixel Image ◽  
Diffraction Patterns ◽  
Modern Analytical

The Zeiss EM912 is a new digital, side-entry, 120 kV TEM/STEM for materials science, with omega magnetic imaging energy filter. Smallest probe is 1.6 nm. We have evaluated the 912 for quantitative CBED because we believe that the zero-loss filtered diffraction pattern is the most accurately quantifiable signal of any on a modern analytical TEM/STEM instrument. A double tilt holder and W filament were used. The magnetic filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient parallel (area) detection. Comparisons with FEG STEM instruments depend on field of view - for a 103X103 pixel image, recording time with the Omega filter using LaB6 is 1000 times less than that of a STEM with a FEG (103 times brighter) for the same dose. For accurate measurement of structure-factor amplitudes and phases, elastic energy-filtered data must be used. This Bloch-wave refinement method has now been automated using "Simplex" multivariate analysis.

Zero-loss omega-filtered REM and RHEED on the new Zeiss 912

1991 ◽  
Vol 49 ◽  
pp. 616-617
Author(s):  
J.C.H. Spence ◽  
J. Mayer
Keyword(s):  
Electron Microscopy ◽  
Materials Science ◽  
Surface States ◽  
Ccd Camera ◽  
Dark Field ◽  
Ion Pump ◽  
Magnetic Imaging ◽  
Reflection Electron Microscopy ◽  
Diffraction Patterns ◽  
Large Background

The Zeiss 912 is a new fully digital, side-entry, 120 Kv TEM/STEM instrument for materials science, fitted with an omega magnetic imaging energy filter. Pumping is by turbopump and ion pump. The magnetic imaging filter allows energy-filtered images or diffraction patterns to be recorded without scanning using efficient parallel (area) detection. The energy loss intensity distribution may also be displayed on the screen, and recorded by scanning it over the PMT supplied. If a CCD camera is fitted and suitable new software developed, “parallel ELS” recording results. For large fields of view, filtered images can be recorded much more efficiently than by Scanning Reflection Electron Microscopy, and the large background of inelastic scattering removed. We have therefore evaluated the 912 for REM and RHEED applications. Causes of streaking and resonance in RHEED patterns are being studied, and a more quantitative analysis of CBRED patterns may be possible. Dark field band-gap REM imaging of surface states may also be possible.

Electron spectroscopic imaging and diffraction: applications II materials science

1992 ◽  
Vol 50 (2) ◽  
pp. 1198-1199
Author(s):  
J. Mayer
Keyword(s):  
Electron Microscopy ◽  
Energy Loss ◽  
Materials Science ◽  
Spectroscopic Imaging ◽  
Electron Spectroscopic Imaging ◽  
Imaging Spectrometer ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
Electron Spectroscopic Diffraction ◽  
Electron Energy Loss

With imaging energy filters becoming commercially available in transmission electron microscopy many of the limitations of conventional TEM instruments can be overcome. Energy filtered images of diffraction patterns can now be recorded without scanning using efficient parallel (2-dimensional detection. We have evaluated a prototype of the Zeiss EM 912 Omega, the first commercially available electron microscope with integrated imaging Omega energy filter. Combining the capabilities of the imaging spectrometer with the principal operation modes of a TEM gives access to many new qualitative and quantitative techniques in electron microscopy. The basis for all of them is that the filter selecte electrons within a certain energy loss range ΔE1 <ΔE < ΔE2 and images their contribution to an image (electron spectroscopic imaging, ESI) or a diffraction pattern (electron spectroscopic diffraction, ESD) In many applications the filter is only used to remove the inelastically scattered electrons (elastic or zero loss filtering). Furthermore, the electron energy loss spectrum can be magnified and recorded with serial or parallel detection.

A Novel TEM Technique for Characterizing As-Grown CVD Diamond Films

1991 ◽  
Vol 49 ◽  
pp. 956-957 ◽  
Author(s):  
Z.L. Wang ◽  
J. Bentley ◽  
R.E. Clausing ◽  
L. Heatherly ◽  
L.L. Horton
Keyword(s):  
Diamond Films ◽  
Chemical Vapor ◽  
Growth Direction ◽  
Dark Field ◽  
Growth Surface ◽  
Specimen Preparation ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
First Time ◽  
Microstructural Studies

Microstructural studies by transmission electron microscopy (TEM) of diamond films grown by chemical vapor deposition (CVD) usually involve tedious specimen preparation. This process has been avoided with a technique that is described in this paper. For the first time, thick as-grown diamond films have been examined directly in a conventional TEM without thinning. With this technique, the important microstructures near the growth surface have been characterized. An as-grown diamond film was fractured on a plane containing the growth direction. It took about 5 min to prepare a sample. For TEM examination, the film was tilted about 30-45° (see Fig. 1). Microstructures of the diamond grains on the top edge of the growth face can be characterized directly by transmitted electron bright-field (BF) and dark-field (DF) images and diffraction patterns.

Computer analysis of side-band holography in STEM

1991 ◽  
Vol 49 ◽  
pp. 684-685
Author(s):  
M.A. Gribelyuk ◽  
J.M. Cowley
Keyword(s):  
Interference Pattern ◽  
Computer Analysis ◽  
Side Band ◽  
Diffraction Plane ◽  
Illumination System ◽  
Probe Size

Recently the use of a biprism in a STEM instrument has been suggested for recording of a hologram. A biprism is inserted in the illumination system and creates two coherent focussed beams at the specimen level with a probe size d= 5-10Å. If one beam passes through an object and another one passes in vacuum, an interference pattern, i.e. a hologram can be observed in diffraction plane (Fig.1).

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.

Nanoscale 3D Chemical Mapping by Spectroscopic Electron Tomography

2002 ◽  
Vol 738 ◽  
Author(s):  
Günter Möbus ◽  
Ron C. Doole ◽  
Beverley J. Inkson
Keyword(s):  
Materials Science ◽  
Electron Tomography ◽  
Region Of Interest ◽  
Atom Probe ◽  
Lattice Plane ◽  
Chemical Mapping ◽  
Bragg Scattering ◽  
Electron Spectroscopic Imaging ◽  
Contrast Mechanism ◽  
Data Volume

ABSTRACTElectron Tomography is shown to be applicable to problems of materials science if a contrast mechanism is used which provides a projection relationship for crystals not depending on lattice plane orientation. Energy filtered TEM (EFTEM) in its mode of electron spectroscopic imaging (ESI) and STEM-EDX-Mapping are, subject to limitations, suitable image formation techniques. The spectroscopic operation not only allows to overcome Bragg scattering artefacts, but offers the possibility of recording 4-dimensional data (volume and energy) of a region of interest, otherwise only known from NMR and XAS/XANES tomography at larger length-scales and from field-ion microscopy (atom probe) under restrictive conditions.

scholarly journals Evolution of Metastable Structures at Bimetallic Surfaces from Microscopy and Machine-Learning Molecular Dynamics

2020 ◽  
Author(s):  
Jin Soo Lim ◽  
Jonathan Vandermause ◽  
Matthijs A. van Spronsen ◽  
Albert Musaelian ◽  
Yu Xie ◽  
...  
Keyword(s):  
Machine Learning ◽  
Molecular Dynamics ◽  
Materials Science ◽  
Automated Analysis ◽  
Layer By Layer ◽  
Surface Restructuring ◽  
Bimetallic Systems ◽  
Metastable Structures ◽  
Mechanistic Investigation ◽  
First Time

Restructuring of interfaces plays a crucial role in materials science and heterogeneous catalysis. Bimetallic systems, in particular, often adopt very different composition and morphology at surfaces compared to the bulk. For the first time, we reveal a detailed atomistic picture of long-timescale restructuring of Pd deposited on Ag, using microscopy, spectroscopy, and novel simulation methods. By developing and performing accelerated machine-learning molecular dynamics followed by an automated analysis method, we discover and characterize previously unidentified surface restructuring mechanisms in an unbiased fashion, including Pd-Ag place exchange and Ag pop-out, as well as step ascent and descent. Remarkably, layer-by-layer dissolution of Pd into Ag is always preceded by an encapsulation of Pd islands by Ag, resulting in a significant migration of Ag out of the surface and a formation of extensive vacancy pits within a period of microseconds. These metastable structures are of vital catalytic importance, as Ag-encapsulated Pd remains much more accessible to reactants than bulk-dissolved Pd. Our approach is broadly applicable to complex multimetallic systems and enables the previously intractable mechanistic investigation of restructuring dynamics at atomic resolution.

Castaing’s Electron Microprobe and Its Impact on Materials Science

2001 ◽  
Vol 7 (2) ◽  
pp. 178-192 ◽  
Author(s):  
Dale E. Newbury
Keyword(s):  
Electron Microprobe ◽  
Materials Science ◽  
Critical Time ◽  
Materials Engineering ◽  
Macro Scale ◽  
Materials Science And Engineering ◽  
Basic Infrastructure ◽  
The Impact ◽  
First Time

Abstract The development of the electron microprobe by Raymond Castaing provided a great stimulus to materials science at a critical time in its history. For the first time, accurate elemental analysis could be performed with a spatial resolution of 1 µm, well within the dimensions of many microstructural features. The impact of the microprobe occurred across the entire spectrum of materials science and engineering. Contributions to the basic infrastructure of materials science included more accurate and efficient determination of phase diagrams and diffusion coefficients. The study of the microstructure of alloys was greatly enhanced by electron microprobe characterization of major, minor, and trace phases, including contamination. Finally, the electron microprobe has proven to be a critical tool for materials engineering, particularly to study failures, which often begin on a micro-scale and then propagate to the macro-scale with catastrophic results.

Microdiffraction from Cleaved Si-Si1-xGex Multilayers

1989 ◽  
Vol 160 ◽  
Author(s):  
W. T. Pike
Keyword(s):  
Cross Section ◽  
Structural Information ◽  
Scanning Transmission Electron Microscope ◽  
High Angle ◽  
Small Probe ◽  
Periodicity Analysis ◽  
Transmission Electron ◽  
Probe Size ◽  
Scanning Transmission ◽  
Diffraction Patterns

AbstractUsing the nanometer probe available in the dedicated scanning transmission electron microscope (STEM) local structural information can be obtained from individual layers in [100] grown Si-Si1-xGex multilayer structures. Furthermore the small probe size enables cleaved specimens with their very large wedge angles to be analyzed in cross-section. Diffraction patterns are shown from multilayers of varying periodicity. Analysis of the patterns concentrates on the higher order Laue zone (holz) reflections in the high angle excess ring . The behaviour of the excess holz reflections indicates the transition from a strained layer superiattice to a dislocated structure as the thickness of the layers increases for a given composition.

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