Measurement of K‐shell flourescence yield and Kα/Kβ intensity ratio for nickel

Abstract

For application of the fundamental parameter approach to quantitative chemical analysis of mixtures by X-ray fluorescence, accurate knowledge is required of fluorescence yields and relative intensities of X-ray lines of the various elements involved. The spread in published data suggests, however, that these parameters are not known with as much accuracy as could be used profitably. In this paper we describe a method by which K-shell fluorescence yield and Ka/KP intensity ratio can both be measured in the same experiment to within approximately 0.5 % for pure elements available as thin polycrystalline foil. Results are given for the particular case of nickel (Z = 28) for which we find WK = 0.452 k 0.002 and Ka/KP = 6.91 k 0.035, but the method is readily applicable to any element whose atomic number falls in the approximate range 20 5 2 5 50 and which can be obtained in suitable physical form. A key factor in the experimental design is use of a non-dispersive (intrinsic germanium) X-ray analyzer; this makes it possible to employ a very simple transmission geometry which can be characterized quite precisely. Experimental conditions, and precautions needed to obtain accurate and consistent results, are described in some detail. Among other corrections applied, allowance is made for scattering of both exciting and fluorescent radiation within the sample. The limiting sources of error appear to be counting statistics and residual uncertainties in calculating corrections for scattering. Among these residual uncertainties are errors in correcting scattering coefficients for anomalous dispersion. Such errors are significant only when evaluating f~, the K-shell excitation efficiency; the important product ~K U K can, however, be determined (~K W K = 0.398 f 0.002) with greater reliability than OK itself.

Radial temperature profiles for a large sample of galaxy clusters observed with XMM-Newton

“…Perhaps, the most important justification for our efforts in this direction is that, for the next 5-10 years, there will be no experiments with comparable or improved capabilities, as far as low surface brightness emission is concerned. (Keith & Loomis 1978). The correlation between broken power-law and Gaussian parameters is very weak.…”

“…The intrinsic width was always fixed to zero, except for Al and Si lines for which it was fixed to 0.0022 keV to allow for minor mismatches in energy calibrations for different observations. Normalizations of Kα, Al, and Si lines were free, while normalizations of Kβ lines were forced to be one seventh of the correspondent Kα line (Keith & Loomis 1978). The correlation between broken power-law and Gaussian parameters is very weak.…”

X-ray spectrometry

“…Fluorescence yields and excitation efficiencies are also required for any fundamental approach to quantitative X-ray fluorescence spectrometry. Careful experimentation is the keynote of fluorescence yield determinations by Keith and Loomis (90).…”

X-ray spectrometric analysis of major and selected minor elements in silicate rocks utilizing an automatic fusion technique

“…Ben-Haim (1980) and Mainardi and others (1981Mainardi and others ( , 1982Mainardi and others ( , 1982 have demonstrated the necessity of developing coefficients derived from binary systems before application to multi-component systems. Keith andLoomis (1978, 1978) stressed the need for accurate measurements of both fluorescence yields and relative intensities and of making scattering corrections in applying the fundamental parameters method. Perhaps the most novel approach is that of Asada and others (1980), who utilized the relationship between the reciprocals of the line intensities of the elements of interest and the element weight fractions to obtain quantitative results for either liquids or fused samples.…”