Energy dispersive analysis by x-rays

Figure 11.1 SEM images of Pd/6H-aSiC (a) and Pd atom identified by energy dispersion analysis by X-ray spectroscopy (b)...

No impurities were encountered in the single crystals at the minimal detection level of the EDAX (energy-dispersive analysis by X rays) technique. 

As indicated in Fig. 7.2, X-rays are among the by-products in an electron microscope. Already at the beginning of this century, people knew that matter emits X-rays when it is bombarded with electrons. The explanation of the phenomenon came with the development of quantum mechanics. Nowadays, it is the basis for determining composition on the submicron scale and, with still increasing spatial resolution, is used in the technique referred to as Electron Microprobe Analysis (EMA), Electron Probe Microanalysis (EPMA) or Energy Dispersive Analysis of X-rays (EDAX, EDX) [21]. 

In nature this common set is typically further restricted over wide geographic areas because of the influence or otherwise of soil-forming factors, the most important of which are parent material and degree of weathering. Thus, a typical sample of soil will contain a suite of around six to ten different major minerals. A major mineral may be defined as one that is present at a concentration of a few percent or more, at which it will be readily detectable by routine techniques such as x-ray provider diffraction (XRPD). It is also known as energy-dispersive x-ray analysis (EDXA) or energy-dispersive analysis of x-ray (EDAX) or microscopic examination, either optical or electron. It is also not uncommon for several other minerals to be present in any given soil but usually in amounts that put them below the routine detection limits of many techniques. Nonetheless, these accessory, or trace, minerals can often be concentrated by some means that separates the soil sample into different physical or chemical fractions. Such procedures effectively lower... 

I was characterized by powder X-ray diffraction (PXRD), energy dispersive analysis of X-rays (EDAX), chemical analysis, thermogravimetric analysis (TGA) and IR spectroscopy. EDAX analysis indicated the ratio of Mn S to be 3 2. The presence of fluorine was confirmed by analysis and the percentage of fluorine estimated by EDAX in a field emission scanning electron microscope was also satisfactory. Thermogravimetric analysis also confirms the stoichiometry of the compound. Bond valence sum calculations6 and the absence of electron density near fluorine in the difference Fourier map also provide evidence for the presence of fluorine. The sulfate content was found to be 30.8% compared to the expected 32% on the basis of the formula. 

BN nanotubes were prepared by a standard literature procedure.7 BN nanotubes were prepared by the reaction of B2C>3 with multi-walled carbon nanotubes (MWNTs) in the presence of ammonia at 1250 °C for 3 h. A grey spongy product was obtained after the reaction indicating the presence of unreacted MWNTs along with BN nanotubes. The product was washed with hot water to remove excess B2O3. The excess carbon present in the product was removed by oxidation at 800 C in low-pressure air (20 mPa). Scanning electron microscope (SEM) and energy dispersive analysis of X-rays (ED AX) were performed with... 

The composites as well as the nanowires were characterized by several techniques. Scanning electron microscopy (SEM) images and energy dispersive analysis of x-rays (EDAX) were obtained with a Leica S-440I microscope fitted with a Link ISIS spectrometer. Infrared (IR) spectra were recorded on small pieces of the samples embedded in KBr pellets using a Broker FT-IR spectrometer. DSC was carried out on the samples ( 7 mg) with a scanning rate of 20 K min-1 between 120 and 260 °C using a Mettler-Toledo DSC. 

As illustrated by Fig. 10.4, an electron microscope offers additional possibilities for analyzing the sample. Diffraction patterns (spots from a single-crystal particle and rings from a collection of randomly oriented particles) enable one to identify crystallographic phases as in XRD. Emitted X-rays are characteristic for an element and allow for a determination of the chemical composition of a selected part of the sample (typical dimension 10 nm). This technique is called electron microprobe analysis (EMA, EPMA) or, referring to the usual mode of detection, energy dispersive analysis of X-rays (EDAX or EDX). Also the Auger electrons carry information on sample composition, as do the loss electrons. The latter are potentially informative on the low Z elements, which have a low efficiency for X-ray fluorescence. 

Saka S, Thomas RJ, Gratzl JS (1978) Lignin distribution Determination by energy-dispersive analysis of X-rays Tappi 61(1) 73-76... 

A paper on new developments in the characterisation of polymers in the solid state must include a discussion of the possibilities offered by scanning electron transmission and the ancillary detection devices EDX (energy dispersive analysis of X-rays) and EELS (electron energy loss spectroscopy). 

Finally, the surfaces of the cores are examined both optically and by secondary electron microscopy to determine the extent of microstructural changes that are occuring due to atmospheric exposure. Energy dispersive analysis of x-rays (EDAX) also serves to detect atmospheric particles which have deposited onto the core surface. All this information can then be used to at least qualitatively identify deterioration processes that may be occuring. 

S Saka, RJ Thomas, IS Gratzl. Lignin Distribution Determination by Energy-Dispersive Analysis of X-rays. Tappi 61(l) 73-76, 1978. 

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