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

Another coaxial shaft e 2 drives a gear a 2 meshing

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Another coaxial shaft E 2 drives a gear A 2 meshing with a stationary gear B 2. The shaft is directly connected to a gear A 3 and the wheel G . The gear A 2 has an arm, which carries a shaft J that follows the same track as the second crystal. A planetary gear K , which meshes with the gear A 3, generates the 4 θ motion needed to receive the X-rays diffracted by the second crystal. A Soller slit S is inserted between the sample and the first crystal to avoid vertical divergence of the X-rays. Figure 4.80 is an example of the comparison of the energy resolution of the double crystal spectrometer to the single crystal spectrometer. The high wavelength resolution of the double crystal spectrometer is useful for chemical state analyses. There are studies using double crystal spectrometers, such as
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298 N. Kawahara and T. Shoji D : Second crystal E1 P : Proportional counter K J C A1 A2 A3 M G B2 B1 S : Soller slit F : First crystal Fig. 4.79. A double crystal spectrometer of (+ +) configuration [103] 101.5 102.0 102.5 103.0 103.5 104.0 104.5 Sample: Al metal Crystal: ADP Spectrum: Al-K a Single crystal spectrometer FWHM:0.2550 degree (2.616eV) Double crystal spectrometer FWHM:0.0799 degree (0.820eV) 2 q (degree) Fig. 4.80. Al-K α spectrum taken with a single crystal spectrometer (dotted line) and with a double crystal spectrometer (solid line) valence analysis of metal compounds [104] and, as a recent study, electronic state analysis of cobalt in lithium ion battery [105]. Double crystal spectrometers have the following advantages compared to X-ray photoelectron spectrometry (XPS or ESCA): Ultra high vacuum is not required. Insulators are analyzable as well as conductors. It is not a surface analysis but a bulk measurement.
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X-Ray Detectors and XRF Detection Channels 299 4.4.5 Selected Applications Suitable for WDXRF Boron in BPSG (Boro-Phospho-Silicate Glass) BPSG has been a widely used material as interlayer insulation films in the semiconductor industry. As controlling the composition of the material is crit- ical for the property, the analysis of the content of boron and phosphorus in BPSG layers takes a key roll in the process. Equipping a gas-flow proportional counter with an ultrathin (sub- µ m) polymer window for detecting and using a synthetic multilayer for dispersing, WDXRF spectrometer realizes sufficient analyzing efficiency [106]. Phosphorus in Silicon The measurement of dopant content such as phosphorus in silicon is another important application in the semiconductor field. However, to detect P-K α (2.013 keV) in the huge silicon peaks (Si-K α : 1.74 keV, Si-K β : 1.836 keV) is not practical with an EDXRF spectrometer. On the other hand, when using a WDXRF spectrometer equipped with germanium (111) (2 d = 0 . 65327 nm) or graphite (0002) (2 d = 0 . 6705 nm), there is no interference of the silicon fluorescence with the phosphorus fluorescence. This fact is explained by the Bragg’s equation (4.62). The equation shows that when the X-ray wavelength is longer than the 2 d value of the crystal, no Bragg diffraction occurs. This is the case for Si-K α (0.7126 nm) or Si-K β (0.6753 nm) with the crystals given above but not for P-K α (0.6159 nm).
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