[B._Beckhoff,_et_al.]_Handbook_of_Practical_X-Ray_(b-ok.org).pdf

Long wavelength x rays emitted from an analyzed

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Long wavelength X-rays emitted from an analyzed sample are reflected totally from the surface of an SML analyzer and as a result, an increase in background radiation can be seen occasionally.
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1 Introduction 13 When higher order reflections of short wavelength X-rays emitted from a sample interfere with the analyzing radiation, an SML analyzer modified by an appropriate choice of the thickness ratio of reflecting to spacing layers is used to suppress the higher order X-ray reflections. 1.3.4 Total Reflection Mirrors In order to obtain a higher intensity of measuring X-rays, electron bombard- ment excitation was adopted. For soft X-ray measurement, Franks and Bray- brook used X-ray optics consisting of the combination of a collimator, a total reflection mirror, and a windowless photomultiplier, as shown in Fig. 1.3 [58]. Herglotz improved the measuring system for soft X-ray measurement, shown in Fig. 1.3 [59]. Using electron bombardment excitation, the measur- ing system was made up of a curved surface paraffin mirror, receiving slit, and a windowless photomultiplier. Later on, an X-ray excitation method was developed for routine applications [60]. Arai sought for practical solutions to measure ultrasoft X-rays and demon- strated that the combination of a rhodium target end window tube with a thin beryllium window and a total reflection mirror along with a selected filter could be applied for the detection of B-K α , C-K α , N-K α and O-K α lines using a standard X-ray fluorescence spectrometer. The quantitative determination of boron oxide in boron glasses, carbon in steel, nitrogen in various chemical compound substances, and oxygen in coal were carried out [60]. Boron oxide in glasses in the range of 1 to 20 wt% could be analyzed with a precision of 0.2 wt% at lower concentration and 0.42 wt% at 19 wt%; the analytical ac- curacy was 0.65 wt% corrected with K 2 O and PbO. Carbon in carbon steel, cast iron, and stainless steel were measured. The analytical error composed of X-ray intensity precision and grinding effect error on the sample surface was about 0.01% in carbon and stainless steel and 0.01 wt% at the concentration of 3.82 wt% in cast iron. The accuracy was 0.01–0.02 wt% in carbon and stainless steel and 0.05 wt% in the range of 2–4 wt% in cast iron. Overlapping influ- ences of molybdenum, niobium, tungsten, and tantalum and an absorption influence of matrix effect of silicon were found [60]. Oxygen measurement in coal or iron ores and nitrogen measurement in various materials were carried out and matrix effects were studied for the improvement of accuracy. For industrial application, Sugimoto, Akiyoshi, and Kondou studied the determination of carbon in pig iron and obtained analytical results for carbon in the range of 3.5–4.7 wt% with a reproducibility of 0.05 wt% and an accuracy of 0.083 wt% using a Rigaku multi-fixed channel spectrometer provided with a total reflection mirror for the detection of C-K α X-rays [61].
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  • Spring '14
  • MichaelDudley

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