Shape of X-ray Peak in EDS Measurements - Practical Electron Microscopy and Database - - An Online Book - |
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Microanalysis | EM Book http://www.globalsino.com/EM/ | ||||||||
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The EDS measurement with Si (silicon) detectors is highly linear when calibrated over the energy range from 1 keV to 10 keV. In general, for X-ray peaks above 1 keV, it is sufficient to evaluate the X-ray intensities by considering the measured X-ray peaks as a Gaussian distribution for a single photon energy. In this case, the intensity as a function of energy is given by (see Figure 1755),
In fact, most software available on commercial EDS systems uses the Gaussian approximation to describe the observed shape of an X-ray peak. Figure 1755. Gaussian distribution of the shape of X-ray peaks. According to the Hyperment function, the asymmetry of the X-ray peaks measured from the photon-detector interactions can be theoretically obtained by adding two analytical expressions S(E) and D(E) to describe the spectroscopic features. [1] Therefore, the measured X-ray line shape P(E) as a function of the analyzed photon energy E, can be given by, Note that the peak height of characteristic X-rays is inversely proportional to the energy resolution of the detector.
[1] J. L. Campbell, A. Perujo and B. M. Millman, Analytic description of Si(Li) spectral lineshapes due to monoenergetic photons, X-Ray Spectrometry, 16(5), 195–201, 1987.
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