Preliminary Observations on the Chemistry and Biology of the Lorica in a Collared Flagellate (Stephanoeca Diplocostata Ellis)

1974 ◽  
Vol 54 (2) ◽  
pp. 269-276 ◽  
Author(s):  
B. S. C. Leadbeater ◽  
I. Manton
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Hydrofluoric Acid ◽  
Light And Electron Microscopy ◽  
Amorphous Form ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Biological Aspects ◽  
Stephanoeca Diplocostata

Evidence for the presence of silica in the costae of Stephanoeca diplocostata Ellis has been provided by a combination of light and electron microscopy. The solubility of costae in hydrofluoric acid has been demonstrated. The presence of silicon in the costae has been strongly confirmed by means of the X-ray analytical electron microscope (EMMA) but tests for a crystalline substructure by means of electron diffraction were negative; it is concluded that silicon is present in a crystallographically amorphous form. Preliminary observations on other biological aspects of the organism include the presence of a sac-like membrane between the lorica and protoplast, the presence of immature costal strips within the cytoplasm and the nature of ingested food. The phyletic position of the group is briefly discussed with special reference to mitochondrial substructure.

Analytical Formulae for Calculation of X-Ray Detector Solid Angles in the Scanning and Scanning/Transmission Analytical Electron Microscope

2014 ◽  
Vol 20 (4) ◽  
pp. 1318-1326 ◽  
Author(s):  
Nestor J. Zaluzec
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Solid Angle ◽  
Analytical Electron Microscopy ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Scanning Transmission ◽  
Analytical Formulae ◽  
Detector Configurations

AbstractClosed form analytical equations used to calculate the collection solid angle of six common geometries of solid-state X-ray detectors in scanning and scanning/transmission analytical electron microscopy are presented. Using these formulae one can make realistic comparisons of the merits of the different detector geometries in modern electron column instruments. This work updates earlier formulations and adds new detector configurations.

Microstructoral and Chemical Analysis Using Electron Beams: The Analytical Electron Microscope

1987 ◽  
Vol 31 ◽  
pp. 9-24
Author(s):  
A. D. Romig
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Chemical Analysis ◽  
Prior Knowledge ◽  
Electron Beams ◽  
Analytical Electron Microscopy ◽  
X Ray ◽  
Basic Understanding ◽  
Analytical Electron ◽  
Analytical Electron Microscope

This plenary paper is intended to be an introduction to the capabilities and limitations of analytical electron microscopy (AEM). The description to be given assumes no prior knowledge of AEM or any other electron microscopy, scanning or transmission. However, a basic understanding of x-ray generation and detection will be assumed.

scholarly journals Overcoming Severe XEDS Peak Overlaps with the AEM

2006 ◽  
Vol 14 (2) ◽  
pp. 34-37
Author(s):  
Scott D. Walck
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Electron Microscope ◽  
Energy Dispersive Spectroscopy ◽  
Analytical Techniques ◽  
Maximum Energy ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Scanning Electron

Of all the analytical techniques in electron microscopy, X-ray energy dispersive spectroscopy (XEDS) is perhaps the most useful. It provides a quick identification of the elements and even with semiquantitative methods; a reasonable composition can be obtained. However, in the scanning electron microscopy (SEM), there are materials systems in which severe peak overlaps of heavier elements L and M lines cannot be easily deconvolved with lighter elements' K lines. In addition, without a sufficient overvoltage in the SEM, even identification of the heavier elements can be difficult. In the analytical electron microscope (AEM), there is always sufficient overvoltage to excite all of the elements' K-lines. However, all of the K-lines might not be able to be detected with commercially available instruments. This is illustrated in Fig.l where the maximum energy of the detector system might be set to 10, 20, or 40 keV.

Application of analytical electron microscopy to the study of partitioning of silicon in a 2 wt% Si eutectoid steel

1978 ◽  
Vol 36 (1) ◽  
pp. 616-617
Author(s):  
N. Ridley ◽  
S.A. Al-Salman ◽  
G.W. Lorimer
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Analytical Electron Microscopy ◽  
Eutectoid Steel ◽  
Minimum Diameter ◽  
Thin Foils ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Transformation Front

The application of the technique of analytical electron microscopy to the study of partitioning of Mn (1) and Cr (2) during the austenite-pearlite transformation in eutectoid steels has been described in previous papers. In both of these investigations, ‘in-situ’ analyses of individual cementite and ferrite plates in thin foils showed that the alloying elements partitioned preferentially to cementite at the transformation front at higher reaction temperatures. At lower temperatures partitioning did not occur and it was possible to identify a ‘no-partition’ temperature for each of the steels examined.In the present work partitioning during the pearlite transformation has been studied in a eutectoid steel containing 1.95 wt% Si. Measurements of pearlite interlamellar spacings showed, however, that except at the highest reaction temperatures the spacing would be too small to make the in-situ analysis of individual cementite plates possible, without interference from adjacent ferrite lamellae. The minimum diameter of the analysis probe on the instrument used, an EMMA-4 analytical electron microscope, was approximately 100 nm.

point-Analysis Using the Extrapolation Method in the Analytical Electron microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 430-431
Author(s):  
Zenji Horita ◽  
Ryuzo Nishimachi ◽  
Takeshi Sano ◽  
Minoru Nemoto
Keyword(s):  
Electron Microscope ◽  
Extrapolation Method ◽  
X Ray ◽  
Absorption Correction ◽  
Point Analysis ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Data Points ◽  
Identical Composition ◽  
X Ray Absorption

Absorption correction is often required in quantitative x-ray microanalysis of thin specimens using the analytical electron microscope. For such correction, it is convenient to use the extrapolation method[l] because the thickness, density and mass absorption coefficient are not necessary in the method. The characteristic x-ray intensities measured for the analysis are only requirement for the absorption correction. However, to achieve extrapolation, it is imperative to obtain data points more than two at different thicknesses in the identical composition. Thus, the method encounters difficulty in analyzing a region equivalent to beam size or the specimen with uniform thickness. The purpose of this study is to modify the method so that extrapolation becomes feasible in such limited conditions. Applicability of the new form is examined by using a standard sample and then it is applied to quantification of phases in a Ni-Al-W ternary alloy.The earlier equation for the extrapolation method was formulated based on the facts that the magnitude of x-ray absorption increases with increasing thickness and that the intensity of a characteristic x-ray exhibiting negligible absorption in the specimen is used as a measure of thickness.

Peak-to-background measurements on a 300-kV TEM/STEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1236-1237 ◽  
Author(s):  
S. M. Zemyan ◽  
D. B. Williams
Keyword(s):  
Electron Microscope ◽  
X Ray ◽  
Background Ratio ◽  
Window Method ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Cr Film

As has been reported elsewhere, a thin evaporated Cr film can be used to monitor the x-ray peak to background ratio (P/B) in an analytical electron microscope. Presented here are the results of P/B measurements for the Cr Ka line on a Philips EM430 TEM/STEM, with Link Si(Li) and intrinsic Ge (IG) x-ray detectors. The goal of the study was to determine the best conditions for x-ray microanalysis.We used the Fiori P/B definition, in which P/B is the ratio of the total peak integral to the average background in a 10 eV channel beneath the peak. Peak and background integrals were determined by the window method, using a peak window from 5.0 to 5.7 keV about Cr Kα, and background windows from 4.1 to 4.8 keV and 6.3 to 7.0 keV.

Optimizing Spatial Resolution for X-ray Microanalysis

2001 ◽  
Vol 7 (S2) ◽  
pp. 694-695
Author(s):  
Eric Lifshin ◽  
Raynald Gauvin ◽  
Di Wu
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
Spatial Resolution ◽  
Maximum Diameter ◽  
Thin Sections ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Limiting Value ◽  
Made In

In Castaing’s classic Ph.D. dissertation he described how the limiting value of x-ray spatial resolution for x-ray microanalysis, of about 1 μm, was not imposed by the diameter of the electron beam, but by the size of the region excited inside the specimen. Fifty years later this limit still applies to the majority of measurement made in EMAs and SEMs, even though there is often a need to analyze much finer structures. When high resolution chemical analysis is required, it is generally necessary to prepare thin sections and examine them in an analytical electron microscope where the maximum diameter of the excited volume may be as small as a few nanometers. Since it is not always possible or practical, it is important to determine just what is the best spatial resolution attainable for the examination of polished or “as received” samples with an EMA or SEM and how to achieve it experimentally.

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