Energy-dispersive spectrometry

The analyst has two practical means of measuring the energy distribution of X rays emitted from the specimen energy-dispersive spectrometry and wavelength dispersive spectrometry. These two spectrometers are highly complementary the strengths of each compensate for the weaknesses of the other, and a well-equipped electron probe instrument will have both spectrometers. 

H. Vare, Aluminum polyphosphate in the ectomycorrhizal fungus Siiillus variega-tiis (Fr.) O. Kuntze as revealed by energy dispersive spectrometry. New Phytol. 7/6 663 (1990). 

Energy-dispersive spectrometry (EDS) is a technique of X-ray spectroscopy that is based on the simultaneous collection and energy dispersion of characteristic X-rays. Typical ED detectors are thermoelectrically cooled semiconductors (usually operated at 77 K), PIN diodes,... 

The source of Au was most likely the gold crucible generally used for crystal growing. A comparative analysis of the crystal energy dispersive spectrometry using a SEM (q.v.) identified the primary elements, plus a very weak peak for Au and no indication of Cr and Fe traces. This demonstrates the advantage of PIXE over SEM in terms of sensitivity for trace element detection. 

These authors produced TEM samples of Bi-doped, Sb-doped and Ag-doped copper foils, thinned to electron transparency using conventional preparation procedures. In all cases the presence of impurity segregation was confirmed using conventional X-ray energy-dispersive spectrometry. The EELS measurements were carried out with a STEM operating at 100 keV, with a nominal probe size of 1 nm (full width at half maximum) with a current of about 0.5 nA. The conditions required to optimize detection sensitivity for interface analysis require the highest current density and are not consistent with achieving the smallest probes. 

Robertson, J.L. and J.A. McLean. 1985. Correspondence of the LC 50 for arsenic trioxide in a diet-incorporation experiment with the quantity of arsenic ingested as measured by X-ray, energy-dispersive spectrometry. Jour. Econ. Entomol. 78 1035-1036. 

Table 5.2 Summary of selected analytical methods for molecular environmental geochemistry. AAS Atomic absorption spectroscopy AFM Atomic force microscopy (also known as SFM) CT Computerized tomography EDS Energy dispersive spectrometry. EELS Electron energy loss spectroscopy EM Electron microscopy EPR Electron paramagnetic resonance (also known as ESR) ESR Electron spin resonance (also known as EPR) EXAFS Extended X-ray absorption fine structure FUR Fourier transform infrared FIR-TEM Fligh-resolution transmission electron microscopy ICP-AES Inductively-coupled plasma atomic emission spectrometry ICP-MS Inductively-coupled plasma mass spectrometry. Reproduced by permission of American Geophysical Union. O Day PA (1999) Molecular environmental geochemistry. Rev Geophysics 37 249-274. Copyright 1999 American Geophysical Union...

Because of the instrumental requirements, these are usually not routine monitoring techniques. However, unlike other methods, they give detailed information on particle shapes. In addition, chemical composition information can be obtained using transmission electron microscopy (TEM) or scanning electron microscopy (SEM) combined with energy-dispersive spectrometry (EDS). The electron beam causes the sample to emit fluorescent X-rays that have energies characteristic of the elements in the sample. Thus a map showing the distribution of elements in the sample can be produced as the electron beam scans the sample. 

X-ray fluorescence (XRF). The sample is irradiated with monochromatic X-rays that eject electrons from the inner shells of the elements. When an electron from an outer shell of the ion drops into the vacancy, it emits characteristic X-rays whose wavelength is used to identify the element and whose intensity is related to the amount present. XRF is used primarily for elements heavier than magnesium because of the weak fluorescence of lighter elements and absorption of the X-rays within the particles. The combination of transmission or scanning electron microscopy (TEM/SEM) with X-ray fluorescence, also known as energy-dispersive spectrometry (EDS), was discussed in Section B.2b. 

Enamel and bone, strontium isotope analysis, 102-104 Energy dispersive spectrometry (EDS), scanning electron microscopy, Seip textiles, 35 Energy dispersive X-ray fluorescence (EDXRF), elemental analyses copper-based coins, 231-245 copper coins, Herodian prutah, 246-257... 

Energy-dispersive spectrometry (EDS) composition based on characteristic x-ray emission induced by electron beam Particle recognition by BSE... 

Micromineralogical studies of these coal wastes were performed by electron microscopy coupled with energy dispersive spectrometry. Because this technique observes such a small fraction of the sample at any one time, the results must be interpreted carefully. Nevertheless, one can perform elemental analyses while retaining the spatial resolution of the microscope. This is difficult, if not impossible, with other techniques. These studies confirmed that most of the trace elements are associated with various types of clays. In addition, the trace... 

Summary. The various differences between wavelength-dispersive and energy-dispersive spectrometry have been described in this chapter. All in all, wavelength dispersion by a crystal spectrometer is superior, chiefly because of its better resolution for most elements of interest, for the quantitative determination of several elements in a complex sample with high accuracy. Energy dispersion has a special place in microanalysis, in portable spectrometers, or wherever fast, semi-quantitative analyses are required. 

This second edition includes an account of new developments made possible by the semiconductor detector and pulse-height analysis, namely, energy-dispersive spectrometry and diffractometry. Applications of position-sensitive detectors are also described. 

Xao XEDS XES XMP XPS XRD XRDF XRF Xyl xanthosine X-ray energy-dispersive spectrometry X-ray emission spectroscopy xanthosine 5 -monophosphate, xanthosine 5 -phosphate X-ray photoelectron spectroscopy X-ray diffraction X-ray radial distance function X-ray fluorescence xylose... 

In contrast to XRD methods that may introduce sample preparation artifacts (see Jiang et al. 1997 Li et al. 1998), TEM integrated with selected-area electron diffraction (SAED) and energy dispersive spectrometry (analytical electron microscopy, AEM) measurements, provides direct, in situ observations on rock microtextures, crystallite size distributions, lattice imperfections of crystallites and interstratification (see the extensive reviews by Peacor 1992 and Merriman and Peacor 1999). TEM observations on selected portions of thinned (ion-milled) whole rock samples contradict the fundamental particle theory of Nadeau et al. (1984a,b,c summarized recently by Nadeau 1998). The observations show that phyllosilicate domains with interstratified structures form coherent boundaries, and therefore, MacEwan-type crystallites do exist in quasi-undisturbed rocks (Peacor 1998). In addition, AEM studies may provide reliable mineral-chemical data on the phases devoid of any external or internal impurities. 

ECD electron capture detector Ecogenetics genetic predisposition for an individual reaction to environmental factors edema pathological accumulation of fluid in the tissue spaces (also known as dropsy) EDS energy dispersive spectrometry EDTA ethyl enediamine tetraacetic acid (chelating agent) used in analysis and therapy... 

All the microanalysis work was done in a Jeol-100 CX electron microscope fitted with a STEM unit, a X-ray detector and a Tracor-Northern 5500 console.The compositional microanalysis was carried out by energy dispersive spectrometry on bulky Adams Pt particles modified by Au deposition. Table 5 gives the mean composition of Pt particles. It appears that Au is preferentially deposited on particle rims (edges and corners) than on flat planes. 

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