A Scanning Transmission Microscopy and Energy-Dispersive X-ray Microanalysis of Idiopathic Ocular Calcification and Oxalosis in AIDS Patients

1999 ◽  
Vol 23 (4) ◽  
pp. 223-231 ◽  
Author(s):  
I. Pecorella, A. Ciardi, A. Scordin
Author(s):  
J.M. Titchmarsh

The advances in recent years in the microanalytical capabilities of conventional TEM's fitted with probe forming lenses allow much more detailed investigations to be made of the microstructures of complex alloys, such as ferritic steels, than have been possible previously. In particular, the identification of individual precipitate particles with dimensions of a few tens of nanometers in alloys containing high densities of several chemically and crystallographically different precipitate types is feasible. The aim of the investigation described in this paper was to establish a method which allowed individual particle identification to be made in a few seconds so that large numbers of particles could be examined in a few hours.A Philips EM400 microscope, fitted with the scanning transmission (STEM) objective lens pole-pieces and an EDAX energy dispersive X-ray analyser, was used at 120 kV with a thermal W hairpin filament. The precipitates examined were extracted using a standard C replica technique from specimens of a 2¼Cr-lMo ferritic steel in a quenched and tempered condition.


Author(s):  
J. Bentley ◽  
E. A. Kenik

Instruments combining a 100 kV transmission electron microscope (TEM) with scanning transmission (STEM), secondary electron (SEM) and x-ray energy dispersive spectrometer (EDS) attachments to give analytical capabilities are becoming increasingly available and useful. Some typical applications in the field of materials science which make use of the small probe size and thin specimen geometry are the chemical analysis of small precipitates contained within a thin foil and the measurement of chemical concentration profiles near microstructural features such as grain boundaries, point defect clusters, dislocations, or precipitates. Quantitative x-ray analysis of bulk samples using EDS on a conventional SEM is reasonably well established, but much less work has been performed on thin metal foils using the higher accelerating voltages available in TEM based instruments.


Author(s):  
S. Wu ◽  
A. Van Daele ◽  
W. Jacob ◽  
R. Gijbels ◽  
A. Verbeeck ◽  
...  

There is a considerable interest for the study of the elemental distribution and composition in silver halide photographic emulsions, particularly for the microanalysis of individual microcrystals. In this work, elemental distributions and contents of tabular and cubic silver halide microcrystals were obtained by backscattered electron imaging (BSEI), scanning transmission electron imaging (STEI), x-ray mapping and x-ray microanalysis in a scanning electron microscope (STEM) combined with energy-dispersive x-ray analysis (EDX).Several kinds of silver halide microcrystals were prepared, After removing the gelatin, repeated centrifugation and washing in distilled water, the grains were resuspended and dispersed onto carbon coated 50 mesh copper grids. All analyses were carried out on a JEOL 1200 EX electron microscope equipped with detectors for backscattered, secondary and transmitted electrons and an energy dispersive x-ray analysis system. An image processing system was used for acquiring and processing BSE images, STE images and x-ray maps. The role of the image processing computer system (IBAS Kontron) is twofold: it allows to optimize the acquisition conditions and to process the images afterwards.


Author(s):  
L. E. Thomas

Continuing evolution of energy-dispersive x-ray spectrometer (EDS) systems has greatly advanced x-ray detector performance in analytical electron microscopes. The latest detectors offer improved energy resolution, count rate performance, geometrical collection efficiency, durability, and efficiency for light and heavy elements. Innovative detector designs for transmission and scanning transmission electron microscopes (TEM/STEMs) include such features as liquid-nitrogen-free operation, in situ de-icing of the detector crystal, user cleanable windows, demountable windows, ultrahigh vacuum compatibility (including adaptations to allow microscope bakeouts without removing the detector), beam damage protection, and microscope interfaces with optimized collection geometries. Divergent design philosophies have produced a variety of systems with specialized features, and users may face hard choices in selecting the best detector for the job. The aim of this paper is to review the current state of EDS detector development and the importance of the performance improvements to TEM/STEM users.


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