Precise method for measuring spatial coherence in TEM beams using Airy diffraction patterns

Microscopy ◽  
2017 ◽  
Vol 67 (1) ◽  
pp. 1-10
Author(s):  
Jun Yamasaki ◽  
Yuki Shimaoka ◽  
Hirokazu Sasaki
Keyword(s):  
Coherence Length ◽  
Spatial Coherence ◽  
Beam Diameter ◽  
Remarkable Feature ◽  
Aperture Diameter ◽  
Point Spread ◽  
Transmission Electron ◽  
Wide Range ◽  
Electron Microscopes ◽  
Diffraction Patterns

Abstract We have developed a method to precisely measure spatial coherence in electron beams. The method does not require an electron biprism and can be implemented in existing analytical transmission electron microscopes equipped with a post-column energy filter. By fitting the Airy diffraction pattern of the selector aperture, various parameters such as geometric aberrations of the lens system and the point-spread function of the diffraction blurring are precisely determined. From the measurements of various beam diameters, components that are attributed to the partial spatial coherence are successfully separated from the point-spread functions. A linear relationship between the spatial coherence length and beam diameter is revealed, thus indicating that a wide range of coherence lengths can be determined by our proposed method as long as the coherence length remains >80% of the aperture diameter. A remarkable feature of this method is its ability to simultaneously determine diffraction blurring and lens aberrations. Possible applications of this method are also discussed.

Reduction of Specimen Contamination in Electron-Beam Instruments

1976 ◽  
Vol 34 ◽  
pp. 576-577
Author(s):  
G. Lehmpfuhl ◽  
P. J. Smith
Keyword(s):  
Electron Beam ◽  
Cold Trap ◽  
Beam Diameter ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Hydrocarbon Molecules ◽  
Electron Microscopes ◽  
Combination Of Methods ◽  
Convergent Beam ◽  
Very High

Specimens being observed with electron-beam instruments are subject to contamination, which is due to polymerization of hydrocarbon molecules by the beam. This effect becomes more important as the size of the beam is reduced. In convergent-beam studies with a beam diameter of 100 Å, contamination was observed to grow on samples at very high rates. Within a few seconds needles began forming under the beam on both the top and the underside of the sample, at growth rates of 400-500 Å/s, severely limiting the time available for observation. Such contamination could cause serious difficulty in examining a sample with the new scanning transmission electron microscopes, in which the beam is focused to a few angstroms.We have been able to reduce the rate of contamination buildup by a combination of methods: placing an anticontamination cold trap in the sample region, preheating the sample before observation, and irradiating the sample with a large beam before observing it with a small beam.

A Structural Model for a Quasi-Crystalline Material Derived from TEM

1990 ◽  
Vol 48 (1) ◽  
pp. 48-49
Author(s):  
Jan-Olov Bovin ◽  
Osamu Terasaki ◽  
Jan-Olle Malm ◽  
Sven Lidin ◽  
Sten Andersson
Keyword(s):  
High Resolution ◽  
Electron Diffraction ◽  
Structural Model ◽  
Image Intensifier ◽  
Crystalline Materials ◽  
Icosahedral Phases ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Diffraction Patterns ◽  
Quasi Crystals

High resolution transmission electron microscopy (HRTEM) is playing an important role in identifying the new icosahedral phases. The selected area diffraction patterns of quasi crystals, recorded with an aperture of the radius of many thousands of Ångströms, consist of dense arrays of well defined sharp spots with five fold dilatation symmetry which makes the interpretation of the diffraction process and the resulting images different from those invoked for usual crystals. The atomic structure of the quasi crystals is not established even if several models are proposed. The correct structure model must of course explain the electron diffraction patterns with 5-, 3- and 2-fold symmetry for the phases but it is also important that the HRTEM images of the alloys match the computer simulated images from the model. We have studied quasi crystals of the alloy Al65Cu20Fe15. The electron microscopes used to obtain high resolution electro micrographs and electron diffraction patterns (EDP) were a (S)TEM JEM-2000FX equipped with EDS and PEELS showing a structural resolution of 2.7 Å and a IVEM JEM-4000EX with a UHP40 high resolution pole piece operated at 400 kV and with a structural resolution of 1.6 Å. This microscope is used with a Gatan 622 TV system with an image intensifier, coupled to a YAG screen. It was found that the crystals of the quasi crystalline materials here investigated were more sensitive to beam damage using 400 kV as electron accelerating voltage than when using 200 kV. Low dose techniques were therefore applied to avoid damage of the structure.

The Observation of NBC Precipitates In Steels In The Nanometer Range Using A Field Emission Gun Scanning Electron Microscope

1997 ◽  
Vol 3 (S2) ◽  
pp. 1243-1244 ◽  
Author(s):  
Raynald Gauvin ◽  
Steve Yue
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Field Emission ◽  
Incident Electron Energy ◽  
Beam Diameter ◽  
Probe Diameter ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

The observation of microstructural features smaller than 300 nm is generally performed using Transmission Electron Microscopy (TEM) because conventional Scanning Electron Microscopes (SEM) do not have the resolution to image such small phases. Since the early 1990’s, a new generation of microscopes is now available on the market. These are the Field Emission Gun Scanning Electron Microscope with a virtual secondary electron detector. The field emission gun gives a higher brightness than those obtained using conventional electron filaments allowing enough electrons to be collected to operate the microscope with incident electron energy, E0, below 5 keV with probe diameter smaller than 5 nm. At 1 keV, the electron range is 60 nm in aluminum and 10 nm in iron (computed using the CASINO program). Since the electron beam diameter is smaller than 5 nm at 1 keV, the resolution of these microscopes becomes closer to that of TEM.

scholarly journals Atomically resolved tomographic reconstruction of nanoparticles from Single Projection: influence of amorphous carbon support

2020 ◽  
Author(s):  
Pritam Banerjee ◽  
Chiranjit Roy ◽  
Subhra Kanti De ◽  
Antonio J. Santos ◽  
Francisco M. Morales ◽  
...  
Keyword(s):  
Amorphous Carbon ◽  
Tomographic Reconstruction ◽  
Carbon Film ◽  
Carbon Support ◽  
Atomic Scale ◽  
Structure Property ◽  
Transmission Electron ◽  
Wide Range ◽  
Correlation Information ◽  
Electron Microscopes

Abstract Nanoparticles have a wide range of applications due to their unique geometry and arrangement of atoms. For a precise structure-property correlation, information regarding atomically resolved 3D structures of nanoparticles is utmost beneficial. Though modern aberration-corrected transmission electron microscopes can resolve atoms with sub-angstrom resolution, an atomic-scale 3D reconstruction of nanoparticle is a challenge using tilt series tomography due to high radiation damage. Instead, inline 3D holography based tomographic reconstructions from single projection registered at low electron doses are more suitable for defining atoms dispositions at nanostructures. Nanoparticles are generally supported on amorphous carbon film for TEM experiments. However, neglecting the influence of carbon film on the tomographic reconstruction of the nanoparticle may lead to ambiguity. In order to address this issue, the effect of amorphous carbon support was quantitatively studied using simulations and experiments.

Is a TEM for “Real World” Application Available Presently?

2001 ◽  
Vol 7 (S2) ◽  
pp. 522-523
Author(s):  
W. Probst ◽  
G. Benner ◽  
B. Kabius ◽  
G. Lang ◽  
S. Hiller ◽  
...  
Keyword(s):  
Real World ◽  
Leading Edge ◽  
Ease Of Use ◽  
Real World Application ◽  
Transmission Electron ◽  
Wide Range ◽  
Race Horse ◽  
Electron Microscopes ◽  
Ray Path ◽  
Technological Opportunities

Transmission electron microscopes have been built along with and guided by technological opportunities since the last five decades. Even though there are some “workhorse” type of microscopes, these instruments are still more or less built from the technological viewpoint and less from the viewpoint of ease of use in a wide range of applications. On the other hand, leading edge applications are the drivers for the development and the use of leading edge technology. The result then is a “race horse” which is of very limited benefit in “Real world”.During the last decade computers have been integrated to build microscope systems. in most cases, however, computers still have to deal with obsolete electron optical ray path designs and thus, have to be used more to overcome the problems of imperfect optics and bad design of ray paths than to provide optimized “Real world” capabilities.

SHaRE: Collaborative materials science research

1988 ◽  
Vol 46 ◽  
pp. 804-805
Author(s):  
Edward A. Kenik ◽  
Karren L. More
Keyword(s):  
Electron Microscope ◽  
Materials Science ◽  
Analytical Electron Microscopy ◽  
Science Research ◽  
Atom Probe ◽  
Probe Field ◽  
Transmission Electron ◽  
Wide Range ◽  
Analytical Electron ◽  
Electron Microscopes

The Shared Research Equipment (SHaRE) Program provides access to the wide range of advanced equipment and techniques available in the Metals and Ceramics Division of ORNL to researchers from universities, industry, and other national laboratories. All SHaRE projects are collaborative in nature and address materials science problems in areas of mutual interest to the internal and external collaborators. While all facilities in the Metals and Ceramics Division are available under SHaRE, there is a strong emphasis on analytical electron microscopy (AEM), based on state-of-the-art facilities, techniques, and recognized expertise in the Division. The microscopy facilities include four analytical electron microscopes (one 300 kV, one 200 kV, and two 120 kV instruments), a conventional transmission electron microscope with a low field polepiece for examination of ferromagnetic materials, a high voltage (1 MV) electron microscope with a number of in situ capabilities, and a variety of EM support facilities. An atom probe field-ion microscope provides microstructural and elemental characterization at atomic resolution.

High-performance EM-002B optical column construction for future expansion

1993 ◽  
Vol 51 ◽  
pp. 256-257
Author(s):  
K. Shirota ◽  
K. Moriyama ◽  
S. Mikami ◽  
A. Ando ◽  
O. Nakamura ◽  
...  
Keyword(s):  
High Performance ◽  
Cold Trap ◽  
Objective Lens ◽  
Transmission Electron ◽  
Probe Size ◽  
Wide Range ◽  
Electron Microscopes ◽  
Time Required ◽  
Modern Analytical ◽  
Typical User

Since modern analytical transmission electron microscopes must have a wide range of illumination conditions (from “mm” to “nm” probe size), an additional lens (one of the condenser lenses, usually called the “mini-lens”) is arranged immediately above the objective lens pole pieces. As a result, it has become very difficult to install an exchange mechanism for the objective pole pieces, which used to be done routinely.To overcome this, TOPCON Electron Microscope EM-OO2B incorporated a new mechanism which can be exchanged quite easily and reliably by the user. This mechanism makes a space to exchange pole pieces, without column disassembly, by precisely driven external mechanisms (Fig. 1). The time required for a typical user to carry out such exchange is usually 15 to 20 minutes, and it will take not more than two hours for high resolution image or analysis after exchange. This time is also shortened by the fact that an anti-contamination cold trap is not generally required in the case of EM-OO2B.

Instrumentation and Computation

1990 ◽  
Vol 48 (1) ◽  
pp. 2-3
Author(s):  
P.B. Hirsch
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Materials Science ◽  
Image Interpretation ◽  
Specimen Preparation ◽  
Scanning Tunnelling Microscope ◽  
Transmission Electron ◽  
Wide Range ◽  
Electron Microscopes ◽  
Types Of Information

The benefit to society arising from developments in instrumentation and computation can be judged primarily by the advances in knowledge and understanding generated by their application in different branches of science, covered in the other papers in this symposium. Without advances in instrumentation none of these advances is possible; developments in instrumentation and in image interpretation are therefore fundamental to and precede scientific advances in fields in which knowledge of structure is important. There is little doubt that the revolutionary first step was the development of the transmission electron microscope (TEM) in 1931 by Ernst Ruska; a second was the development of the scanning electron microscope (SEM); and the third the introduction of the scanning tunnelling microscope (STM) for high resolution surface imaging, by Binnig and Rohrer.The TEM and SEM have undergone continuous developments over the last 50 years or so, and have had a far-reaching impact in a wide range of disciplines; the STM is a relative newcomer but no doubt it too will have an increasing impact in furthering our understanding of solids and surfaces in particular. Once the basic instruments became available subsequent developments have been driven by the demands of the scientific disciplines in which these instruments have been applied. Many of the new developments in instrumentation and interpretation have been pioneered by the users themselves, and these in turn have led to modifications in commercial instruments to make such advances in technique available to the user community as a whole. Other developments have been initiated directly by the manufacturers as a result of a perceived need. There has been and continues to be a close interaction between the developers of hardware (not only of electron microscopes but also of ancillary equipment, e.g. microanalysis attachments, image processing equipment, specialist specimen stages, and specimen preparation facilities) and the users, leading to extensions in the range of applications and the types of information which can be obtained by electron microscopy. The following examples from the developments of electron microscopy in Materials Science illustrate these interactions and the particular advances arising from specific developments:

Tutorial on Off-Axis Electron Holography

2002 ◽  
Vol 8 (6) ◽  
pp. 447-466 ◽  
Author(s):  
Michael Lehmann ◽  
Hannes Lichte
Keyword(s):  
Materials Science ◽  
Electron Holography ◽  
Large Area ◽  
Transmission Electron ◽  
Step Procedure ◽  
Medium Resolution ◽  
Wide Range ◽  
Electric Potentials ◽  
Electron Microscopes ◽  
Powerful Electron

Through recent years, off-axis electron holography has helped us to understand and to overcome some experimental restrictions in transmission electron microscopy. With development of powerful electron microscopes, slow-scan CCD cameras, and computers, holography is not an academic technique anymore used by specialized laboratories. Holography has proven its wide range of applications in solving real-world problems in materials science and biology. At medium resolution, that is, on nanometer scale, holography allows access to large area phase contrast produced by magnetic fields and electric potentials. In the high-resolution domain, holography unveils its power by unscrambling amplitude and phase of the electron wave, resulting in an improved lateral resolution up to the information limit. Holography is a thoroughly quantitative method, and, in combination with the perfect zero-loss filtering inherent to this method, the interpretation of the reconstructed data is strongly simplified. After outlining the basics of holography, in this tutorial we focus on development of a step-by-step procedure for recording and reconstruction of holograms. At the end, some recent applications are discussed.

scholarly journals FEI Titan G3 50-300 PICO

2015 ◽  
Vol 1 ◽  
Author(s):  
Karsten Tillmann ◽  
Juri Barthel ◽  
Lothar Houben
Keyword(s):  
Electron Gun ◽  
Atomic Scale ◽  
Fourth Generation ◽  
High Brightness ◽  
Transmission Electron ◽  
Wide Range ◽  
Schottky Type ◽  
Resolution Analysis ◽  
Technical Specifications ◽  
Electron Microscopes

The FEI Titan G3 50-300 PICO is a unique fourth generation transmission electron microscope which has been specifically designed for the investigation of a wide range of solid state phenomena taking place on the atomic scale and thus necessitating true atomic resolution analysis capabilities. For these purposes, the FEI Titan G3 50-300 PICO is equipped with a Schottky type high-brightness electron gun (FEI X-FEG), a monochromator unit, and a Cs probe corrector (CEOS DCOR), a Cs-Cc achro-aplanat image corrector (CEOS CCOR+), a double biprism, a post-column energy filter system (Gatan Quantum 966 ERS) as well as a 16 megapixel CCD system (Gatan UltraScan 4000 UHS). Characterised by a TEM and STEM resolution well below 50 pm at 200 kV, the instrument is one of the few chromatically-corrected high resolution transmission electron microscopes in the world. Typical examples of use and technical specifications for the instrument are given below.

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