scholarly journals Low Dose High-Resolution Electron Microscopy (HREM) of Poly(3,4-ethylene dioxythiophene) (PEDOT) Films

2011 ◽  
Vol 17 (S2) ◽  
pp. 1452-1453
Author(s):  
J Wu ◽  
D Martin
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

Structural analysis of the surface-layer protein of spirillum serpens by high-resolution electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 738-739
Author(s):  
W. H. Wu ◽  
R. M. Glaeser
Keyword(s):  
Electron Microscopy ◽  
Surface Layer ◽  
Structural Analysis ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Surface Layer Protein ◽  
Morphological Unit ◽  
Resolution Electron

Spirillum serpens possesses a surface layer protein which exhibits a regular hexagonal packing of the morphological subunits. A morphological model of the structure of the protein has been proposed at a resolution of about 25 Å, in which the morphological unit might be described as having the appearance of a flared-out, hollow cylinder with six ÅspokesÅ at the flared end. In order to understand the detailed association of the macromolecules, it is necessary to do a high resolution structural analysis. Large, single layered arrays of the surface layer protein have been obtained for this purpose by means of extensive heating in high CaCl2, a procedure derived from that of Buckmire and Murray. Low dose, low temperature electron microscopy has been applied to the large arrays.As a first step, the samples were negatively stained with neutralized phosphotungstic acid, and the specimens were imaged at 40,000 magnification by use of a high resolution cold stage on a JE0L 100B. Low dose images were recorded with exposures of 7-9 electrons/Å2. The micrographs obtained (Fig. 1) were examined by use of optical diffraction (Fig. 2) to tell what areas were especially well ordered.

Slow-scan CCD cameras and low-dose High-Resolution Electron Microscopy: Direct and quantitative

1994 ◽  
Vol 52 ◽  
pp. 412-413
Author(s):  
M. Pan
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Structural Damage ◽  
Low Dose ◽  
Dynamic Range ◽  
High Resolution Electron Microscopy ◽  
Operating Conditions ◽  
Digital Data ◽  
Ccd Cameras ◽  
Resolution Electron

It has been known for many years that materials such as zeolites, polymers, and biological specimens have crystalline structures that are vulnerable to electron beam irradiation. This radiation damage severely restrains the use of high resolution electron microscopy (HREM). As a result, structural characterization of these materials using HREM techniques becomes difficult and challenging. The emergence of slow-scan CCD cameras in recent years has made it possible to record high resolution (∽2Å) structural images with low beam intensity before any apparent structural damage occurs. Among the many ideal properties of slow-scan CCD cameras, the low readout noise and digital recording allow for low-dose HREM to be carried out in an efficient and quantitative way. For example, the image quality (or resolution) can be readily evaluated on-line at the microscope and this information can then be used to optimize the operating conditions, thus ensuring that high quality images are recorded. Since slow-scan CCD cameras output (undistorted) digital data within the large dynamic range (103-104), they are ideal for quantitative electron diffraction and microscopy.

High Resolution Electron Microscopy of a Novel Zeolite

1997 ◽  
Vol 3 (S2) ◽  
pp. 441-442
Author(s):  
P.A. Crozier ◽  
I.Y. Chan ◽  
C.Y. Chen ◽  
L.W. Finger ◽  
R.C. Medrud ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
X Ray Diffraction ◽  
High Adsorption ◽  
Structural Units ◽  
X Ray ◽  
Resolution Electron ◽  
Crystal Structural

Low-dose high resolution electron microscopy (HREM) is a useful technique for elucidating the structure of zeolites. In recent years a number of zeolite structures have been solved using combinations of different characterization techniques including adsorption measurements, powder x-ray diffraction and low-dose high resolution electron microscopy (for example see ref. 2). We have used these techniques to study the structure of a novel zeolite material. However, great care must be exercised when interpreting data from these techniques in terms of crystal structural units. In this particular case, the structure was recently determined using single crystal x-ray diffraction and showed some surprises.Details of the synthesis of this zeolite are given elsewhere. The high adsorption capacity suggested that this zeolite possessed two interpenetrating channels (either a 10 and a 12 ring or two 12 ring channels). X-ray powder diffraction showed the material to be monoclinic with a= 18.5Å, b= 13.4 Å, c= 7.6 Å β = 101.5°).

Molecular imaging of Organo-Calcium salts by High Resolution Electron Microscopy and Image Processing

1990 ◽  
Vol 48 (1) ◽  
pp. 590-591
Author(s):  
G. Miller ◽  
J.R. Fryer ◽  
W. Kunath ◽  
K. Weiss
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
High Resolution ◽  
Low Dose ◽  
High Resolution Electron Microscopy ◽  
Unit Cell ◽  
Recording Device ◽  
Resolution Electron

Unfortunatly Wolfgang Kunath died January 1990High resolution electron microscopy and image processing are being used to determine the molecular packing within the crystal unit cell of the, organic-azo calcium salt. Due to the beam sensitive nature of the organic moiety which contains both aromatic and and aliphatic components, low dose techniques were used. This concisted of, searching the sample in the diffraction mode to find single crystals exibiting point like reflection to at least .2nm resolution, (fig. 1). Focusing and astigmatism correction was performed by moving the beam of the crystal (off axis). The beam was then moved on axis and a series of four, 10 e/A images taken, (fig. 2). Images were primarily recorded using an on line T.V. recording device. These images were then available for processing using the Semper image processing system. Two crystal orientations were found. Type 1 consisted of thin plate like crystals up to 5um diameter and generally 10nm to 20nm thick. Type 2 were thicker crystals with a 3.2nm lattice spacing. The power specrta of the first low dose images were calculated to asses the quality of the of the structural information present. For the type 1 crystal the power spectrum had to show at least second order reflections in two directions ( fig. 3 ). Type 2 crystals showed the 3.2nm reflection often down to the fith order. These crystals also showed parallel side bands corresponding to a d-spacing of about .8nm. With these results the unit cell was found to be tetragonal with a= .78nm b= 3.2nm c= .78nm. In accordance with the diffraction patterns exibited.

Low Voltage Table-Top Electron Microscopy of Polymer and Organic Molecular Thin Films

2001 ◽  
Vol 711 ◽  
Author(s):  
David C. Martin ◽  
Lawrence F. Drummy ◽  
Junyan Yang ◽  
Eva Coufalova
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
High Resolution ◽  
Low Dose ◽  
Organic Materials ◽  
Low Voltage ◽  
High Technology ◽  
High Resolution Electron Microscopy ◽  
Resolution Electron ◽  
Electron Microscopes

There is intense current interest in the use of polymer and organic molecular materials for high technology devices including transistors, biosensors, and actuators [1]. In order for these materials to achieve their ultimate potential it is imperative to obtain detailed information about their microstructure, especially in the thin film forms central to technological applications. Our research group has been actively developing techniques for high-resolution electron optical examinations of polymers and organic materials, with particular emphasis on low dose high-resolution electron microscopy (HREM) [2]. While this method of examining organic materials' structure has proven to be particularly powerful, current generations of electron microscopes suffer from several problems. They are expensive, require considerable amounts of space, and are time-consuming and fairly difficult to operate. Furthermore, the high voltages normally used in conventional electron microscopes (200-400 kV) provide little contrast when imaging thin films composed of low atomic number components.

Electron microscopy of rabbit FC crystals

1983 ◽  
Vol 41 ◽  
pp. 730-731
Author(s):  
Robert A. Grant ◽  
Laura L. Degn ◽  
Wah Chiu ◽  
John Robinson
Keyword(s):  
Electron Microscopy ◽  
High Resolution ◽  
High Resolution Electron Microscopy ◽  
Molecular Replacement ◽  
X Ray ◽  
X Ray Crystallography ◽  
Resolution Electron ◽  
Replacement Technique ◽  
Hydrated Crystal ◽  
Molecular Structure Analysis

Proteolytic digestion of the immunoglobulin IgG with papain cleaves the molecule into an antigen binding fragment, Fab, and a compliment binding fragment, Fc. Structures of intact immunoglobulin, Fab and Fc from various sources have been solved by X-ray crystallography. Rabbit Fc can be crystallized as thin platelets suitable for high resolution electron microscopy. The structure of rabbit Fc can be expected to be similar to the known structure of human Fc, making it an ideal specimen for comparing the X-ray and electron crystallographic techniques and for the application of the molecular replacement technique to electron crystallography. Thin protein crystals embedded in ice diffract to high resolution. A low resolution image of a frozen, hydrated crystal can be expected to have a better contrast than a glucose embedded crystal due to the larger density difference between protein and ice compared to protein and glucose. For these reasons we are using an ice embedding technique to prepare the rabbit Fc crystals for molecular structure analysis by electron microscopy.

High resolution electron microscopy of lanthanum phosphate crystals

1978 ◽  
Vol 36 (1) ◽  
pp. 274-275
Author(s):  
J. C. Wheatley ◽  
J. M. Cowley
Keyword(s):  
Electron Microscopy ◽  
Catalytic Activity ◽  
High Resolution ◽  
Petroleum Industry ◽  
High Resolution Electron Microscopy ◽  
Lanthanum Phosphate ◽  
Good Catalyst ◽  
Resolution Electron ◽  
Good Catalytic Activity ◽  
Physical And Chemical

Rare-earth phosphates are of particular interest because of their catalytic properties associated with the hydrolysis of many aromatic chlorides in the petroleum industry. Lanthanum phosphates (LaPO4) which have been doped with small amounts of copper have shown increased catalytic activity (1). However the physical and chemical characteristics of the samples leading to good catalytic activity are not known.Many catalysts are amorphous and thus do not easily lend themselves to methods of investigation which would include electron microscopy. However, the LaPO4, crystals are quite suitable samples for high resolution techniques.The samples used were obtained from William L. Kehl of Gulf Research and Development Company. The electron microscopy was carried out on a JEOL JEM-100B which had been modified for high resolution microscopy (2). Standard high resolution techniques were employed. Three different sample types were observed: 669A-1-5-7 (poor catalyst), H-L-2 (good catalyst) and 27-011 (good catalyst).

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