Titlebook: Worked Examples in X-ray Analysis; R. Jenkins,J. L. Vries Textbook 1978Latest edition Macmillan Publishers Limited 1978 analytical chemist

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,Dispersion as a function of ‘d’ spacing,LiF is commonly used as an analysing crystal. The (200) reflection planes are commonly used, having a “.” value of 4.028 Å. It is, however, possible to use reflecting planes with other Miller indices (hkl) for example the (220), the (420) and the (422) planes.

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,Pulse height selection — crystal fluorescence,It is necessary to set up an X-ray spectrometer for the measurement of sodium in a series of rock specimens. An argon/methane flow count­er is being employed and a KAP (potassium hydrogen phthalate) analysing crystal. The rock samples contain quite a lot of calcium and this leads to strong crystal fluorescence.

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Count rate differences with Geiger and proportional counters,A silicon specimen is being examined using nickel filtered Cu K. radiation. The intensities of two reflections are measured with a Geiger-Müller counter and the following counting rates obtained:

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Dispersion of the diffractometer,The dispersion of the diffractometer (dθ/dλ) can be expressed in the given form obtained by differentiating the Bragg law . = 2.sin. .where the angular separation (dθ) of two wavelengths separated by (dλ) is expressed in terms of the diffraction angle θ for a certain spacing ..

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,Counting statistics — variation of standard deviation with counting time,A certain analysis line gave 800 c/s under certain instrumental conditions. Given that the standard deviation (σ) of a given number of counts (.) is equal to √ ., calculate the standard deviation expected in a counting time of 20 seconds.

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