Imaging Ionic Aggregates in Zn-Neutralized Sulfonated Polystyrene Ionomers: Shape and Spatial Heterogeneity

2000 ◽  
Vol 6 (S2) ◽  
pp. 1112-1113
Author(s):  
Brian P. Kirkmeyer ◽  
Robert A. Weiss ◽  
Karen I. Winey
Keyword(s):  
Quantitative Information ◽  
Sulfonated Polystyrene ◽  
Anionic Polymer ◽  
Saxs Data ◽  
Polymer Backbone ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Aggregate Morphology ◽  
Common Technique ◽  
Neutralizing Agent

Ionomers are ionically-associating copolymers whose distinctive rheological and mechanical properties arise from the formation of ionic aggregates. The ionic aggregates form when dipoles of minority anionic polymer backbone segments and cationic neutralizing species locally associate and dissociate among each other. Specific ionomer properties depend upon the base copolymer, the minority constituent and the neutralizing agent. One system that has been studied extensively is sulfonated polystyrene ionomer neutralized with Zn (Zn-SPS). The most common technique to date for studying ionomer morphology is small-angle x-ray scattering (SAXS). This technique has provided quantitative information about the aggregate morphology by imposing morphology models that have not been independently confirmed.In the present study, we demonstrate the capability to directly image the ionic aggregates of Zn-SPS ionomers using scanning transmission electron microscopy (STEM). This method will allow us to confirm or deny the competing morphological models applied to SAXS data. We have applied similar methods to polyethylene-based ionomers.

Electron energy loss spectroscopy (EELS) by scanning transmission electron microscopy (STEM) at low doses

1987 ◽  
Vol 45 ◽  
pp. 116-117 ◽  
Author(s):  
R. Reichelt ◽  
A. Engel ◽  
R. Leapman
Keyword(s):  
Energy Loss ◽  
Structural Information ◽  
Mean Free Path ◽  
Quantitative Information ◽  
Scanning Transmission Electron Microscope ◽  
Thin Specimen ◽  
Scanning Transmission Electron ◽  
Biological Matter ◽  
Transmission Electron ◽  
Scanning Transmission

A scanning transmission electron microscope (STEM) has the unique feature to record simultaneously two types of images with high collection efficiencies. The first type, collected by an annular detector (AD), contains high resolution structural information which is primarily transmitted by elastically scattered electrons. The second type, formed by an electron spectrometer (SP), yields information on the local energy loss spectrum of the inelastically scattered electrons at lower structural resolution. Thus useful quantitative information from biological matter can be obtained: the AD-signal provides the basis for mass mapping and the inelastic one allows the estimation of the local chemical element concentration.For a very thin specimen (T<< ^, T: thickness, A: mean free path between two scattering events) the signal S of the imaging modes mentioned above can be linearly related to the properties of the sample:

Quantitative Information from Image Processing in ADF Stem

1997 ◽  
Vol 3 (S2) ◽  
pp. 1149-1150
Author(s):  
P.D. Nellist ◽  
S.J. Pennycook
Keyword(s):  
Image Processing ◽  
Phase Retrieval ◽  
Quantitative Information ◽  
Scanning Transmission Electron Microscope ◽  
Dark Field ◽  
Phase Problem ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Annular Dark Field ◽  
Incoherent Imaging

Annular dark-field (ADF) imaging in the scanning transmission electron microscope (STEM) at atomic resolution can be regarded as being almost perfect incoherent imaging, which has two major advantages over conventional high-resolution transmission electron microscopy (HRTEM), which is close to being perfectly coherent: Firstly, the images formed are direct structure images of the projected atomic structure, with regions of intensity located at the positions of the atomic columns. Secondly, the images can be written as the convolution between two real and positive functions: a point-spread function given by the intensity of the STEM probe, and an object function that consists of narrow, almost <5-function-like, peaks located exactly over the nuclei of the atomic columns. Thus there is no phase problem in ADF STEM imaging, unlike in conventional HRTEM where phase retrieval techniques such as holography are often employed.The lack of a phase problem in ADF STEM imaging creates immediate opportunities for image processing.

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.

High-Voltage Scanning Electron Microscopy

1970 ◽  
Vol 28 ◽  
pp. 6-7
Author(s):  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Scanning Transmission Electron Microscopy ◽  
Wave Optics ◽  
Contrast Effects ◽  
Transmission Electron ◽  
Mode Of Operation ◽  
Scanning Transmission ◽  
Types Of Information ◽  
Voltage Scanning

The comparison of scanning transmission electron microscopy (STEM) with conventional transmission electron microscopy (CTEM) can best be made by means of the Reciprocity Theorem of wave optics. In Fig. 1 the intensity measured at a point A’ in the CTEM image due to emission from a point B’ in the electron source is equated to the intensity at a point of the detector, B, due to emission from a point A In the source In the STEM. On this basis it can be demonstrated that contrast effects In the two types of instrument will be similar. The reciprocity relationship can be carried further to include the Instrument design and experimental procedures required to obtain particular types of information. For any. mode of operation providing particular information with one type of microscope, the analagous type of operation giving the same information can be postulated for the other type of microscope. Then the choice between the two types of instrument depends on the practical convenience for obtaining the required Information.

Undecagold labeling of tRNA

1991 ◽  
Vol 49 ◽  
pp. 44-45
Author(s):  
James F. Hainfeld ◽  
Kyra M. Alford ◽  
Mathias Sprinzl ◽  
Valsan Mandiyan ◽  
Santa J. Tumminia ◽  
...  
Keyword(s):  
High Resolution ◽  
Transmission Electron Micrograph ◽  
Anticodon Loop ◽  
Electron Micrograph ◽  
Reaction Conditions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The undecagold (Au11) cluster was used to covalently label tRNA molecules at two specific ribonucleotides, one at position 75, and one at position 32 near the anticodon loop. Two different Au11 derivatives were used, one with a monomaleimide and one with a monoiodacetamide to effect efficient reactions.The first tRNA labeled was yeast tRNAphe which had a 2-thiocytidine (s2C) enzymatically introduced at position 75. This was found to react with the iodoacetamide-Aun derivative (Fig. 1) but not the maleimide-Aun (Fig. 2). Reaction conditions were 37° for 16 hours. Addition of dimethylformamide (DMF) up to 70% made no improvement in the labeling yield. A high resolution scanning transmission electron micrograph (STEM) taken using the darkfield elastically scattered electrons is shown in Fig. 3.

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.

The Theoretical Contrast in Scanning and Conventional High Resolution Microscopes

1969 ◽  
Vol 27 ◽  
pp. 170-171
Author(s):  
E. Zeitler ◽  
M. G. R. Thomson
Keyword(s):  
Small Volume ◽  
Volume Element ◽  
Optical Processing ◽  
Image Construction ◽  
Object Interaction ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Optical Treatment ◽  
Electron Microscopes ◽  
Intensity Contrast

In the formation of an image each small volume element of the object is correlated to an areal element in the image. The structure or detail of the object is represented by changes in intensity from element to element, and this variation of intensity (contrast) is determined by the interaction of the electrons with the specimen, and by the optical processing of the information-carrying electrons. Both conventional and scanning transmission electron microscopes form images which may be considered in this way, but the mechanism of image construction is very different in the two cases. Although the electron-object interaction is the same, the optical treatment differs.

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