Energy and wavelength dispersive x-ray

The electron-optical performance of the EPMA system is indistinguishable from that of a conventional scanning electron microscope (SEM) thus, EPMA combines all of the imaging capabilities of a SEM with quantitative elemental analysis using both energy- and wavelength-dispersive X-ray spectrometry. ... 

A Jeol-35 Scanning Electron Microscope equipped with energy-and wavelength- dispersive X-ray spectrometers was used for elemental analysis. Spot analyses were carried out these covered approximately 0.5 pm for the pyrite and 1 pm for the coal. The standard atomic number, absorption and fluorescence (ZAF) corrections were applied to all analyses, using counting times of 200 seconds, an accelerating voltage of 15 kV and a pyrite crystal as standard. 

Elemental analysis can also be performed on SEM samples using x-ray spectrometer attachments [55], The techniques are known as energy dispersive x-ray (EDX) analysis and wavelength dispersive x-ray (WDX) analysis and require installation of a detector in the sample chamber. 

Materials are made up of chemical compounds that in turn are formed by atoms. Atoms have essentially a dense nucleus around which a cloud of electrons balances the electrical charge of the nucleus. If high-energy electrons are shot at matter, some will bounce off the surface, some will penetrate into it producing X-rays, while others will interact with the higher energy electrons (inner shell electrons) of the atoms. These are the principles used for SEM, EDS and wavelength dispersive X-ray spectroscopy (WDS). 

From what has been described above it is obvious that the unfiltered, thick anode, x-ray tube offers considerable flexibility in achieving broadband excitation. Once the appropriate anode material has been selected, the question of the optimum tube voltage and current settings arises. Fundamental differences in the characteristics of the energy-dispersive and wavelength-dispersive x-ray spectrometers lead to different criteria for choosing the optimum tube voltage and current. 

Microscopy techniques can be used to evaluate the size and distribution of particles added to polymer fibers, such as metals that modify the physical, mechanical, or electrical properties. In general, ultrathin sections are examined in either STEM or TEM modes to reveal the particles within the polymer. Energy (EDS) and wavelength dispersive x-ray spectroscopy (WDS) methods are used to map for various elements in order to establish the relation between the particle morphology and chemical composition. A specimen preparation method for x-ray analysis in the SEM is to use a trimmed block face, which remains after cutting thin sections, or to study a thick section. An example of such a study is described below. 

An energy-dispersive X-ray spectrometer and at least one wavelength-dispersive X-ray spectrometer... 

Examples of using reference samples for calibration can be found in several chapters of the uses Methods for Geochemical Analysis (Baedecker 1987). Solid reference sample powders are used in cahbrating the dc arc emission, energy-dispersive X-ray and instrumental neutron activation analyses described, while acid-dissolved rock reference samples are used for IGP emission analyses and fused reference samples are used for wavelength-dispersive X-ray analyses. 

This non-destructive technique is a very suitable tool for rapid in-line analysis of inorganic additives in food products (Price and Major, 1990 Anon, 1995). It can be readily used by non-skilled operators, and dry materials can be pressed into a pellet or simply poured into a sample cup. The principles of this technique related to food analysis are described by Pomeranz and Meloan (1994). A useful Internet site is http //www.xraysite.com, which includes information about different XRF instruments from various companies. Wavelength dispersive X-ray fluorescence (WD-XRF) or bench-top energy dispersive (ED-XRF) instruments are available. XRF is a comparative technique, thus a calibration curve needs to be established using food products of the same type as those to be... 

Recent studies on iron sulfide minerals in coals, minerals in coals, and in situ investigation of minerals in coal all used the scanning electron microscope (SEM) as the primary analytical tool. The ion microprobe mass analyzer (IMMA) is more sensitive than either the energy-dispersive x-ray spectrometer or the wavelength-dispersive x-ray spectrometer, both of which are used as accessories to an electron microscope. 

Within this technique, we include EDX (energy dispersive x-ray analysis), WDX (wavelength dispersive x-ray analysis), and XRF (x-ray fluorescence analysis). In all of these, x-rays emitted from a sample are analyzed. In one case, they are created by bombarding the sample with x-rays (XRF), and in the others, they are created by high energy electron beam as in an SEM (EDX, WDX). 

Microprobe techniques, and their detection limits (given in mgkg ), that have been applied to Al localization include energy dispersive (electron probe) X-ray microanalysis (20), wavelength-dispersive X-ray microanalysis, electron energy loss spectrometry (500), proton probe nuclear microscopy (10), resonance ionization mass spectrometry (3), secondary ion mass spectrometry (1), laser microprobe mass spectrometry (1) and micropartide-induced X-ray emission (Yokel 2000). 

ABSTRACT X-ray spectroinetty (XRF) is a versatile instrumental method for elemental analysis in a wide variety of materials. The performance of three different XRF systems will be con sared a high power wavelength dispersive x-ray spectrometer (WDXRF), a low-power WDXRF, and a bench-top energy dispersive instrument (EDXRF). 

In order to individually analyze the fluorescent X-rays from each element, the spectral separation of the X-rays is required. There are two types of spectrographic methods for XRF. They are wavelength dispersive X-ray spectrometry (WDS, WDX) and energy dispersive X-ray spectrometry (EDS, EDX). The characteristics of WDS and EDS are shown in Table 1. Please refer to the following reference for more detailed explanations of XRF [1]. 

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