Alignment of low-dose STEM images of unstained macromolecules

1984 ◽  
Vol 42 ◽  
pp. 162-163
Author(s):  
J. F. Hainfeld ◽  
P. S. Furcinitti ◽  
J. S. Wall
Keyword(s):  
Low Dose ◽  
Collection Efficiency ◽  
Scanning Transmission Electron Microscope ◽  
Single Particles ◽  
Low Contrast ◽  
Damage Rate ◽  
Software Packages ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Beam Damage

Several studies of molecular structure have successfully employed computer techniques to align images of single particles. Image processing software packages (e.g., P. R. Smith's MDPP system and J. Frank's SPIDER system) have also been developed to facilitate this work. Due to the low contrast and high beam damage rate involved in the use of unstained specimens, most single particle (i.e., non-crystalline) image alignment has been of negatively stained specimens. The scanning transmission electron microscope (STEM), which has a linear transfer function at high resolution rather than the oscillating one inherent to CEMs, operationally overcomes these limitations by providing low dose, high contrast images of unstained material with high collection efficiency.

To What Extent are Inelastically Scattered Electrons Useful in the Stem?

1973 ◽  
Vol 31 ◽  
pp. 286-287 ◽  
Author(s):  
H. Rose
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Electron Correlation ◽  
Quantum Noise ◽  
Collection Efficiency ◽  
Scanning Transmission Electron Microscope ◽  
Electron Cloud ◽  
Scanning Time ◽  
Transmission Electron ◽  
Scanning Transmission

The scanning transmission electron microscope offers the possibility of utilizing inelastically scattered electrons. Use of these electrons in addition to the elastically scattered electrons should reduce the scanning time (dose) Which is necessary to keep the quantum noise below a certain level. Hence it should lower the radiation damage. For high resolution, Where the collection efficiency of elastically scattered electrons is small, the use of Inelastically scattered electrons should become more and more favorable because they can all be detected by means of a spectrometer. Unfortunately, the Inelastic scattering Is a non-localized interaction due to the electron-electron correlation, occurring predominantly at the circumference of the atomic electron cloud.

Studies of Aggregates of Two Muscle Proteins with Scanning Transmission and Conventional Transmission Electron Microscopy

1973 ◽  
Vol 31 ◽  
pp. 600-601 ◽  
Author(s):  
M. K. Lamvik ◽  
M. S. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Striated Muscle ◽  
Collection Efficiency ◽  
Scanning Transmission Electron Microscope ◽  
High Contrast ◽  
Muscle Proteins ◽  
Native Structure ◽  
Preparation Methods ◽  
Signal Selection ◽  
Transmission Electron ◽  
Scanning Transmission

Studies of the structures of various aggregates of proteins from vertebrate striated muscle have begun, using in particular the scanning transmission electron microscope (STEM). The high collection efficiency of this microscope has been noted elsewhere and the contrast advantage and signal selection capabilities have been demonstrated.Although the instrument can produce high contrast images of unstained and unfixed biological material, it is not clear which preparation methods might maintain the native structure of such material. So the study begins on familiar ground with conventionl negatively stained preparations, While later steps will include less conventional methods.Rabbit tropomyosin Mg-tactoids in suspension were received from Dr. Carolyn Cohen (of Children's Cancer Research Foundation, Boston). The tactoids have a primary periodicity of 395 Å. Isolated myofibrils were obtained from Joseph Etlinger (of this University); myosin was extracted from them by a method similar to that of Dow and Stracher.

Toward the biochemistry of individual molecules

1984 ◽  
Vol 42 ◽  
pp. 154-157
Author(s):  
J. S. Wall ◽  
J. F. Hainfeld
Keyword(s):  
Electron Microscope ◽  
Active Sites ◽  
Scanning Transmission Electron Microscope ◽  
List Type ◽  
Type Number ◽  
Low Contrast ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Conventional Microscopy ◽  
Detailed Interpretation

One goal of the Brookhaven STEM group is to enhance the capabilities of the electron microscope as a biochemical tool, while attempting to open up a new field: the Biochemistry of Individual Molecules. Three aspects of molecular biology seem particularly tractable with the STEM (Scanning Transmission Electron Microscope):Size, shape and molecular weightActive sites: location and environmentInteractions in complex systemsAll these areas have been explored to some extent by conventional microscopy, but definitive conclusions are elusive because of low contrast and radiation damage which usually require staining or shadowing to “see” anything. Periodic features may be rendered faithfully, but detailed interpretation falls prey to arguments about positive vs. negative staining, decoration vs. shadowing, flattening, shrinkage, and other such phenomenon.

Mapping functional groups on oxidised multi-walled carbon nanotubes at the nanometre scale

2014 ◽  
Vol 50 (51) ◽  
pp. 6744-6747 ◽  
Author(s):  
A. E. Goode ◽  
N. D. M. Hine ◽  
S. Chen ◽  
S. D. Bergin ◽  
M. S. P. Shaffer ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electron Microscope ◽  
Low Dose ◽  
Scanning Transmission Electron Microscope ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes ◽  
Electron Energy Loss ◽  
Walled Cnts

Functional peaks have been mapped across individual multi-walled CNTs with low-dose, monochromated electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM).

Development of a Field Emission Stem and its Application to Element Analysis

1976 ◽  
Vol 34 ◽  
pp. 524-525
Author(s):  
S. Nomura ◽  
H. Todokoro ◽  
T. Komoda
Keyword(s):  
Field Emission ◽  
Collection Efficiency ◽  
Scanning Transmission Electron Microscope ◽  
Electron Gun ◽  
High Signal ◽  
Element Analysis ◽  
Signal Collection ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Tungsten Tip

The Scanning Transmission Electron Microscope (STEM) has made possible specimen observation with a number of advantages such as high signal collection efficiency. In addition, STEM also permits element analysis of micro-areas, when it is used in conjunction with X-ray and/or electron spectrometers. These advantages become more effective by using a high brightness electron gun.The authors have developed a field emission STEM. The schematic diagram of the instrument is shown in Fig. 1. Electrons emitted from the tungsten tip are focused on a specimen by one electro-static and two magnetic lenses. The field emission tip is surrounded by ion pumps, and the vacuum of the gun chamber is maintained at better than 5xlO-10torr.

scholarly journals Using Your Beam Efficiently: Reducing Electron Dose in the STEM via Flyback Compensation

2022 ◽  
pp. 1-9
Author(s):  
Tiarnan Mullarkey ◽  
Jonathan J. P. Peters ◽  
Clive Downing ◽  
Lewys Jones
Keyword(s):  
Electron Beam ◽  
Strain Measurement ◽  
Scanning Transmission Electron Microscope ◽  
Absolute Minimum ◽  
Electron Dose ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Dose Efficiency ◽  
Specialized Hardware ◽  
Beam Damage

In the scanning transmission electron microscope, fast-scanning and frame-averaging are two widely used approaches for reducing electron-beam damage and increasing image signal noise ratio which require no additional specialized hardware. Unfortunately, for scans with short pixel dwell-times (less than 5 μs), line flyback time represents an increasingly wasteful overhead. Although beam exposure during flyback causes damage while yielding no useful information, scan coil hysteresis means that eliminating it entirely leads to unacceptably distorted images. In this work, we reduce this flyback to an absolute minimum by calibrating and correcting for this hysteresis in postprocessing. Substantial improvements in dose efficiency can be realized (up to 20%), while crystallographic and spatial fidelity is maintained for displacement/strain measurement.

The High Resolution Scanning Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 316-317
Author(s):  
A. V. Crewe
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
High Vacuum ◽  
Scanning Transmission Electron Microscope ◽  
Ultra High Vacuum ◽  
Resolving Power ◽  
Imaging Characteristics ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
The Moment

The high resolution STEM is now a fact of life. I think that we have, in the last few years, demonstrated that this instrument is capable of the same resolving power as a CEM but is sufficiently different in its imaging characteristics to offer some real advantages.It seems possible to prove in a quite general way that only a field emission source can give adequate intensity for the highest resolution^ and at the moment this means operating at ultra high vacuum levels. Our experience, however, is that neither the source nor the vacuum are difficult to manage and indeed are simpler than many other systems and substantially trouble-free.

Resolution Attainable With the Present Day STEM

1973 ◽  
Vol 31 ◽  
pp. 230-231 ◽  
Author(s):  
J. S. Wall ◽  
J. P. Langmore ◽  
H. Isaacson ◽  
A. V. Crewe
Keyword(s):  
Spherical Aberration ◽  
Focal Length ◽  
Incident Beam ◽  
Scanning Transmission Electron Microscope ◽  
Aperture Size ◽  
Magnetic Lens ◽  
Peak Intensity ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Half Angle

The scanning transmission electron microscope (STEM) constructed by the authors employs a field emission gun and a 1.15 mm focal length magnetic lens to produce a probe on the specimen. The aperture size is chosen to allow one wavelength of spherical aberration at the edge of the objective aperture. Under these conditions the profile of the focused spot is expected to be similar to an Airy intensity distribution with the first zero at the same point but with a peak intensity 80 per cent of that which would be obtained If the lens had no aberration. This condition is attained when the half angle that the incident beam subtends at the specimen, 𝛂 = (4𝛌/Cs)¼

Enhancement of Contrast in the CEM and STEM Using Bumpy Specimens and Employing the “Dappled Field” Mode of Operation

1974 ◽  
Vol 32 ◽  
pp. 552-553 ◽  
Author(s):  
L. Gandolfi ◽  
J. Reiffel
Keyword(s):  
Operating Mode ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Specimen Preparation ◽  
Field Mode ◽  
Preparation Methods ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission

Calculations have been performed on the contrast obtainable, using the Scanning Transmission Electron Microscope, in the observation of thick specimens. Recent research indicates a revival of an earlier interest in the observation of thin specimens with the view of comparing the attainable contrast using both types of specimens.Potential for biological applications of scanning transmission electron microscopy has led to a proliferation of the literature concerning specimen preparation methods and the controversy over “to stain or not to stain” in combination with the use of the dark field operating mode and the same choice of technique using bright field mode of operation has not yet been resolved.

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