X-ray EDAX

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]. 

International Model 707 energy dispersive analysis of X-rays (EDAX) accessory. 

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... 

Characterization. CHNS analysis was carried using the Thermo Finnigan FLASH EA 1112 CHNS analyzer. Energy dispersive analysis of X-rays (EDAX) was carried using the OXFORD ED AX system. Infrared spectroscopic studies of KBr pellets were recorded in the mid-IRregion (Bruker IFS-66v). Thermogravimetric analysis was carried out (Metler-Toledo) in nitrogen atmosphere (flow rate... 

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. 

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. 

The alternative approach to detection and analysis incorporates a solid state detector and a multichannel pulse height analysis system. The crystals used are of silicon (of the highly pure intrinsic type), or the lithium drift principle (p. 461) is utilized. All emitted radiations are presented to the detector simultaneously and a spectrum is generated from an electronic analysis of the mixture of voltage pulses produced. Chapter 10 contains a more detailed account of pulse height analysis and solid state detectors. Production of an X-rsy spectrum in this way is sometimes known as energy dispersive analysis of X-rays (EDAX) and where an electron microscope is employed as SEM-EDAX. 

Ion Imaging. A SIMS 1on Image represents the x-y distribution of a species over the surface of the sample. The usefulness of elemental Images has been Illustrated for Auger and electron microprobe energy dispersive X-ray (EDAX) maps SIMS... 

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. 

The catalytic materials were studied with Fourier transform infrared spectroscopy (FTIR), electron scanning microscopy (SEM), energy-dispersive analysis of x-rays (EDAX), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), the differential scanning calorimetry (DSC), elemental analysis (EA) and surface area determination (BET). 

Energy Dispersive Analysis of X-Rays (EDAX). Analysis for the presence of LiBr in slices of the dry extracted hydrogel was performed using a Cambridge scanning electron microscope (SEM) equipped with an EDAX attachment. Each sample was counted for over 200 s at a 200 x magnification. 

Energy Dispersive Analysis of X-Rays (EDAX) was performed to ascertain the composition of the layer-like formation on the SiG grains (point 2) and the needles (point I)... 

Guerrero-Ruiz et al used XRD, TEM, and energy-dispersion analysis with X-rays (EDAX) and MOS to characterize chemical state of FeMe (Me=Co, Ni, Ru, Rh, Pt, Pd and Ir) clusters supported on AC. The FeMe clusters on AC were prepared by reduction in H2 at 723 K. The results showed that small metal crystallites were constituted by alloys, whereas larger metal aggregates appearing as segregation phases consisted of only one metal. The latter accounted for a small portion of the total surface area. In fact, the HYD and HDS activities were dominated by the surface covered with bimetallic clusters. 

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