Structural Analysis of Filaments Using the STEM

2000 ◽  
Vol 6 (S2) ◽  
pp. 862-863
Author(s):  
M. N. Simon ◽  
B. Y. Lin ◽  
J. S. Wall
Keyword(s):  
Scanning Transmission Electron Microscope ◽  
Digital Data ◽  
Mass Analysis ◽  
Biological Origin ◽  
Biotechnology Research ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Different Types ◽  
Scanning Transmission ◽  
History Of

The Scanning Transmission Electron Microscope (STEM) facility at BNL is an NIH Biotechnology Research Resource and as such is available to users with suitable projects, free of charge. Currently, many of our users' projects involve studying the structures of a variety of filaments. Most of these are of biological origin, although a couple involve conducting polymers. The STEM has a long history of being used to study different types of filaments and resolving controversies about their structure.The mainstay of the STEM is mass analysis on unstained, isolated, freeze-dried samples. On these, the STEM can collect in-focus digital data directly. In a scan (8 sec. in real time) of a sample, at each of 512x512 picture elements (pixels), the number of electrons scattered into two annular detectors is recorded. For each pixel, the number of scattered electrons is directly proportional to the mass thickness in that pixel.

X-ray microanalysis of mineralized deposits in a variety of pathological conditions in the brain

1995 ◽  
Vol 53 ◽  
pp. 866-867
Author(s):  
C. A. Ackerley ◽  
L. E. Becker
Keyword(s):  
Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
Small Degree ◽  
X Ray ◽  
Transmission Electron ◽  
Formalin Fixed Paraffin ◽  
Freeze Dried ◽  
Scanning Transmission ◽  
Formalin Fixed Paraffin Embedded ◽  
The Brain

Although a small degree of mineralization can be a common occurrence without associated pathological symptoms, certain diseases of the brain do however exhibit distinct increases in mineralization with characteristic distributions l>2. In this study, tissues from a number of these disorders were prepared for x-ray microanalysis in several ways. Where possible, material was slam frozen on a liquid nitrogen cooled polished copper block, cryosections prepared and freeze dried in the scanning transmission electron microscope (STEM) using a cold stage prior to analysis by energy dispersive x-ray spectrometry (EDS). In addition, samples were freeze substituted for several days, embedded in LR white and cut on dry knives before analysis. Where only formalin fixed paraffin embedded materials were available, .5μ.m sections were cut and mounted on carbon planchets. The specimens were then deparaffinized with xylene and viewed with the backscatter electron detector (BEI) in the scanning electron microscope (SEM) and analyzed by EDS.

Electron microscopy on etched thin foils. A comparative SEM, STEM and TEM analysis

1978 ◽  
Vol 36 (1) ◽  
pp. 126-127
Author(s):  
R. Österlund ◽  
O. Vingsbo
Keyword(s):  
Electron Microscopy ◽  
Scanning Transmission Electron Microscope ◽  
Tem Analysis ◽  
Thin Foils ◽  
Transmission Electron ◽  
Different Types ◽  
Scanning Transmission ◽  
Tem Mode ◽  
Means Of Transmission ◽  
Transmission Studies

During the last decade, much effort has been devoted to relations between structure and mechanical properties, particularly in metals. The need for sophisticated structure studies has increased accordingly. Combinations of different types of microscope methods have been tried, for example by performing optical and scanning electron microscopy (SEM) on etched metallographic sections.Particularly in the case of more intricate phase analyses, it is often necessary to add information about the internal structure by means of transmission electron microscopy (TEM). The scope of the present work has been to combine the advantages of the “classical” methods of studying etched surfaces with those of transmission studies of the same field of observation. For that purpose, the scanning transmission electron microscope (STEM) technique is ideal, and has been applied on thin foils, which, after ordinary electro-polishing, were etched (nital, 10 sec.) and thereby given a structure-related surface topography. The microscope used was a JEOL 200B TEM with scanning attachment, operated at 200 kV in emissive SEM, STEM and conventional TEM mode.

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.

Development of 200 kV Scanning-Transmission Electron Microscope

1974 ◽  
Vol 32 ◽  
pp. 410-411
Author(s):  
H. Koike ◽  
S. Sakurai ◽  
K. Ueno ◽  
M. Watanabe
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Scanning Transmission Electron Microscope ◽  
The Other ◽  
Morphological Observation ◽  
Magnetic Domains ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Backscattered Electron ◽  
Increasing Demand

In recent years, there has been increasing demand for higher voltage SEMs, in the field of surface observation, especially that of magnetic domains, dislocations, and electron channeling patterns by backscattered electron microscopy. On the other hand, the resolution of the CTEM has now reached 1 ∼ 2Å, and several reports have recently been made on the observation of atom images, indicating that the ultimate goal of morphological observation has beem nearly achieved.

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