X-ray fluorescence signals

The particle size distribution of powders in the range 0.2-0.5 pm can be determined by automated electron probe microanalysis, as developed for particle characterization work at the University of Antwerp (see e.g. Ref. [202]). Here the exciting electron beam of a microprobe scans a deposit of the aerosol particles collected on a Nuclepore filter under computer control, and from the detection of element specific x-ray fluorescence signals, the diameters of a large number of particles are determined automatically. As shown by results for AI2O3, the particle size distributions determined by automated electron probe microanalysis agree to a first approximation with those of stray laser radiation (Fig. 62) [203], Deviations, however,... 

Figure 12.4 Schematic setup of the XTA facility at Beamline IIIDD at the APS. A, accelerator B, undulator insertion device C, monochromator. Detector 0 is for intensity normalization, Detector 1 and 2 are for X-ray fluorescence signals from the jet stream of the sample (red) and hence have the soller slit/z-1 filter/plastic scintilator/combo (dark cylinders) in front of the detector. The outputs of the detectors shown by black arrows are amplified and connected to the inputs of the digitizing board (from Agilent)...

Non-destructive analysis is especially valuable in an on line situation. X-ray fluorescence has above all become of major importance for the analysis of inorganic process streams. Cement production is an example of the successful application of this technique. The X-ray analyser can be used for the simultaneous assay of the various feedstocks (iron ore, clay and limestone) for Fe203, A1203, Si02 and CaO. In turn the signals from the analyser are used to control the feedstock supplies to the blending mill and to maintain an optimum product composition. 

Kovarsky et al have used the SIMS method to determine the mole fraction in InGaN [8], Their technique is based on a comparison of the relative signal intensities of CsM+ (M = In, Ga) and does not require reference samples. The SIMS results were independently confirmed by XRD, energy dispersive X-ray fluorescence spectroscopy, EPMA and SNMS, and the absolute value of the InN mole fraction has a relative accuracy <15%. 

Thanks to the linear relationship between the intensity of the characteristic X-ray radiation generated in the sample by electrons and the concentration of the given element, quantitative elemental analysis is also possible. X-ray microanalysis performed using SEM-EDX is, in principle, point analysis and is suitable for studying very small samples of solid materials that are stable in an electron beam. The X-ray fluorescence method, on the other hand, can be applied to the study of both solids and liquids. The signal reaching the detector always originates from a certain sample volume, and thus it is not point analysis. It is more sensitive than the SEM-EDX method. 

X-ray fluorescence (XRF) Archaeometric method for measuring element abundances in inorganic materials X-rays are used to excite atoms to fluoresce and emit a characteristic signal for each element. 

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