Principles of electron structure research at atomic resolution using conventional electron microscopes for the measurement of amplitudes and phases

1970 ◽  
Vol 26 (4) ◽  
pp. 414-426 ◽  
Author(s):  
W. Hoppe
Keyword(s):  
Electron Structure ◽  
Atomic Resolution ◽  
Electron Microscopes ◽  
Structure Research

scholarly journals Data Processing for Atomic Resolution Electron Energy Loss Spectroscopy

2012 ◽  
Vol 18 (4) ◽  
pp. 667-675 ◽  
Author(s):  
Paul Cueva ◽  
Robert Hovden ◽  
Julia A. Mundy ◽  
Huolin L. Xin ◽  
David A. Muller
Keyword(s):  
Energy Loss ◽  
Electron Energy ◽  
Electron Energy Loss Spectroscopy ◽  
Principal Component ◽  
Power Laws ◽  
Atomic Resolution ◽  
Background Error ◽  
Background Estimation ◽  
Electron Microscopes ◽  
Electron Energy Loss

AbstractThe high beam current and subangstrom resolution of aberration-corrected scanning transmission electron microscopes has enabled electron energy loss spectroscopy (EELS) mapping with atomic resolution. These spectral maps are often dose limited and spatially oversampled, leading to low counts/channel and are thus highly sensitive to errors in background estimation. However, by taking advantage of redundancy in the dataset map, one can improve background estimation and increase chemical sensitivity. We consider two such approaches—linear combination of power laws and local background averaging—that reduce background error and improve signal extraction. Principal component analysis (PCA) can also be used to analyze spectrum images, but the poor peak-to-background ratio in EELS can lead to serious artifacts if raw EELS data are PCA filtered. We identify common artifacts and discuss alternative approaches. These algorithms are implemented within the Cornell Spectrum Imager, an open source software package for spectroscopic analysis.

Still “Plenty of Room at the Bottom” for Aberration-Corrected TEM

2011 ◽  
Vol 19 (3) ◽  
pp. 10-14 ◽  
Author(s):  
Joerg R. Jinschek ◽  
Emrah Yucelen ◽  
Bert Freitag ◽  
Hector A. Calderon ◽  
Andy Steinbach
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Atomic Resolution ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
Exciting Time ◽  
The Individual ◽  
Richard Feynman ◽  
Everyday Reality ◽  
Aberration Corrected

In his now-famous 1959 speech on nanotechnology, Richard Feynman proposed that it should be possible to see the individual atoms in a material, if only the electron microscope could be made 100 times better. With the development of aberration correctors on transmission electron microscopes (TEMs) over the last decade, this dream of microscopists to directly image structures atom-by-atom has come close to an everyday reality. Figure 1 shows such a high-resolution transmission electron microscope (HR-TEM) image of a single-wall carbon nanotube obtained with an aberration-corrected TEM. Now that atomic-resolution images have become possible with aberration-corrector technology in both TEM and STEM, we can ask ourselves if we truly have achieved the goal of seeing individual atoms. Most aberration-corrected images exhibiting atomic resolution are not distinguishing individual atoms, but columns of a small number of atoms, so despite this remarkable achievement, there is still “plenty of room at the bottom” in order to move toward seeing, counting, and quantifying individual atoms. In fact, there never has been a more exciting time for electron microscopists.

Instrumentation at the National Center for Electron Microscopy: The atomic resolution microscope

1983 ◽  
Vol 41 ◽  
pp. 310-311 ◽  
Author(s):  
R. Gronsky ◽  
G. Thomas
Keyword(s):  
Electron Microscopy ◽  
Atomic Resolution ◽  
Objective Lens ◽  
Contrast Transfer Function ◽  
Voltage Electron ◽  
Variable Voltage ◽  
New Instrument ◽  
Performance Specifications ◽  
Electron Microscopes ◽  
Point To Point

The Atomic Resolution Microscope (ARM) is one of two unique high voltage electron microscopes at the Lawrence Berkeley Laboratory's National Center for Electron Microscopy (NCEM). This paper reports on the latest results from this new instrument which was manufactured by JEOL, Ltd. to the performance specifications of the NCEM, delivered in January of 1983, and soon to be open to access by the entire microscopy community. Details of its history and development are given in reference 1; its performance specifications are reviewed below.Adopting as a design definition for resolution the first zero crossover of th% phase contrast transfer function at Scherzer defocus, the ARM (Fig. 1) maintains 1.7Å point-to-point resolution over its 400kV to 1000kV operating range. Consequently the microscope can be tuned to a voltage which is below the threshold for knock-on damage in a specimen and used to directly image its contiguous-atom structure. The key to this variable-voltage, high-resolution performance is a top-entry objective stage, which, in addition to ± 40° biaxial tilting, incorporates a height (Z)-control to alter specimen position within the objective lens.

scholarly journals Introduction to high-resolution cryo-electron microscopy

2016 ◽  
Vol 62 (3) ◽  
pp. 383-394
Author(s):  
Mariusz Czarnocki-Cieciura ◽  
Marcin Nowotny
Keyword(s):  
Electron Microscopy ◽  
Nmr Spectroscopy ◽  
Structural Biology ◽  
Atomic Resolution ◽  
Biological Macromolecules ◽  
X Ray ◽  
X Ray Crystallography ◽  
Cryo Electron Microscopy ◽  
Transmission Electron ◽  
Electron Microscopes

For many years two techniques have dominated structural biology – X-ray crystallography and NMR spectroscopy. Traditional cryo-electron microscopy of biological macromolecules produced macromolecular reconstructions at resolution limited to 6–10 Å. Recent development of transmission electron microscopes, in particular the development of direct electron detectors, and continuous improvements in the available software, have led to the “resolution revolution” in cryo-EM. It is now possible to routinely obtain near-atomic-resolution 3D maps of intact biological macromolecules as small as ~100 kDa. Thus, cryo-EM is now becoming the method of choice for structural analysis of many complex assemblies that are unsuitable for structure determination by other methods.

Structure of crystals in dental enamel and synthetic hydroxyapatite

1983 ◽  
Vol 41 ◽  
pp. 44-45
Author(s):  
J. D. McLean ◽  
D. G. A. Nelson
Keyword(s):  
Chemical Composition ◽  
Dental Enamel ◽  
Atomic Resolution ◽  
Starting Point ◽  
High Resolution Images ◽  
Synthetic Hydroxyapatite ◽  
Electron Microscopes ◽  
Lattice Resolution ◽  
Hydroxy Groups ◽  
Hydroxyapatite Crystals

Biological apatites in dental enamel, dentine and bone closely resemble, in chemical composition, the mineral hydroxyapatite with the unit cell Ca10(PO4)6(OH)2. Substitutions occur frequently, e.g. fluoride in place of hydroxy groups, carbonate for phosphate, and with other elements such as magnesium, zinc, strontium, and lead instead of calcium. The substituents are known to influence the response of the material to attack by dilute organic acids and are, therefore, of importance in the process of dental caries.The sub-lattice resolution available with some modern electron microscopes makes it feasible to attempt detection of the effect of substituted groups on the structure of the hydroxyapatite crystals. As a starting point in such a venture we have obtained high-resolution images of apatite crystals and used computer image calculation techniques to interpret the micrographs at near-atomic resolution.

scholarly journals Visualization of biological macromolecules at near-atomic resolution: cryo-electron microscopy comes of age

2019 ◽  
Vol 75 (1) ◽  
pp. 3-11 ◽  
Author(s):  
Alok K. Mitra
Keyword(s):  
Electron Microscopy ◽  
Structural Biology ◽  
Atomic Resolution ◽  
Particle Analysis ◽  
Biological Macromolecules ◽  
Single Particles ◽  
Cryo Electron Microscopy ◽  
Electron Microscopes ◽  
Resolution Single ◽  
Resolution Structure

Structural biology is going through a revolution as a result of transformational advances in the field of cryo-electron microscopy (cryo-EM) driven by the development of direct electron detectors and ultrastable electron microscopes. High-resolution cryo-EM images of isolated biomolecules (single particles) suspended in a thin layer of vitrified buffer are subjected to powerful image-processing algorithms, enabling near-atomic resolution structures to be determined in unprecedented numbers. Prior to these advances, electron crystallography of two-dimensional crystals and helical assemblies of proteins had established the feasibility of atomic resolution structure determination using cryo-EM. Atomic resolution single-particle analysis, without the need for crystals, now promises to resolve problems in structural biology that were intractable just a few years ago.

Dreidimensional abbildende Elektronenmikroskope I. Prinzip der Geräte / Threedimensionally Imaging Electron Microscopes

1972 ◽  
Vol 27 (6) ◽  
pp. 919-929 ◽  
Author(s):  
W. Hoppe
Keyword(s):  
Dark Field ◽  
Imaging Systems ◽  
Atomic Resolution ◽  
Small Object ◽  
Fourier Space ◽  
Bright Field ◽  
Image Construction ◽  
Dark Field Imaging ◽  
Electron Microscopes ◽  
Field Imaging

Abstract Threedimensionally Imaging Electron Microscopes The principles of new electron optical imaging systems will be described which make possible the threedimensional image construction of a small object. Data of threedimensional Fourier space are collected by the registration of several images using primary beams with different tilting angles. The simplest device of such a type - a magnetic fly's eye system - will lead to spherical aberrrations larger than about 20 mm. It will be shown, that there is a good chance to correct “ring zone segment”-systems to reach atomic resolution with or without image-reconstruction-calculations. Not only microscopes with conventional bright field and dark field imaging but also transmission scanning microscopes can be constructed usind these principles.

Electron Microscopy of Solid- Liquid Interfaces: HREM Observation and EELS Analysis

1999 ◽  
Vol 5 (S2) ◽  
pp. 706-707
Author(s):  
H. Saka ◽  
S. Arai ◽  
S. Tsukimoto ◽  
H. Miyai ◽  
M. Konno ◽  
...  
Keyword(s):  
Dynamical Behaviour ◽  
Atomic Resolution ◽  
Chemical Mapping ◽  
Liquid Interfaces ◽  
Transmission Electron ◽  
In Situ Heating ◽  
Electron Microscopes ◽  
Solid Liquid Interface ◽  
Solid Liquid

A solid-liquid interface in the Al–Si system has been observed at near-atomic resolution by in-situ heating experiments inside transmission electron microscopes. Chemical mapping was also attempt to detect distribution of constituent atoms near a solid–hquid interface.Mixtures of Al particles and Si particles, the diameter of which ranged from 200nm to 800nm, were mounted on a specimen–heating holder developed by Kamino and Saka and examined in a Hitachi H–9000NAR and a Hitachi HF–2000 electron microscope, operated at accelerating voltages of 300 and 200kV, respectively. Heating these specimens above the melting point of pure Al inside the microscopes resulted in the melting of the Al particles. The liquid Al reacted with nearby Si, leading to the formation of Al–Si alloy phase. An interface between solid Si and Al–Si alloy hquid and also an interface between solid Al and Al–Si alloy liquid were observed. The dynamical behaviour was recorded continuously using TV–VTR systems. The distribution of Al and Si was visualized using a Gatan imaging filter GIF analyzer.

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