Dependence of the Compton to Rayleigh intensity ratio on the scatterer atomic number in the range of 4(Be) to 31(Ga)

Abstract

Compton to Rayleigh scattering intensity ratios (IC/IR) have been measured using X‐rays with energy 17.44 keV for single‐component materials with atomic number Z from 4 (Be) to 31 (Ga) and binary compounds of stoichiometric composition. The measurements have been performed using two optical schemes: an energy‐dispersive X‐ray fluorescence scheme with a molybdenum secondary target and wavelength‐dispersive X‐ray fluorescence one. The processing of the spectra was carried out by fitting with Pearson VII functions. For single‐component and binary standards, the experimental dependence of the scattering intensity ratio on the atomic number was found to be the same. This confirms the additivity of the contribution of different atoms to the scattering. The dependence has a complex shape but is well described by the theoretical relationship for IC/IR with correction on the difference between Compton and Rayleigh radiation absorption coefficients. Two ranges of atomic number values are defined, in which the effective atomic number Zeff can be determined by the calibration method using this dependence: for Z from 4 to 7 with low error of ΔZeff =±0.15 and for Zeff from 10 to 18 with low error of ΔZeff =±0.69. A change in the shape of the Compton peak and an overestimated value of the of the Compton and Rayleigh peak intensity ratio when passing from a single‐component scatterer (Al or Si) to their oxides Al2O3 or SiO2, respectively, have been revealed.

Determination of binary systems based on light elements by the ratio of the Compton and Rayleigh scattering intensities

“…In experimental measurements, slight deviations from theoretical dependences S ( x , Z i ) and f 2 ( x , Z i ) appear . Therefore, for a more accurate determination of y ( x , Z i ), the regularization solution of the experimental calibration of on Zeff was used (Figure ).…”

“…Recently, the ratio of Compton and Rayleigh scattering intensities has been used in solving both fundamental problems of determining the effective atomic number and mass absorption coefficients and applied problems of adjusting the composition in the XRF analysis, and also for determining the fraction of light elements in the sample bulk and the distribution of light elements along its depth . In our previous work, it was shown that the dependence on the atomic number can be used as a calibration function for identification of single‐component and binary materials in certain ranges of effective atomic numbers Zeff . However, using a single calibration function one can determine the effective atomic number of the single‐component material only.…”

Determination of the screening parameter for 1s electrons in a bound atom by the ratio of the intensities of coherent and incoherent scattering of X‐rays

“…The features of the X‐ray optical scheme of the EDXRF and WDXRF spectrometers are described in Ref. 6. As the primary radiation, fluorescent radiations of secondary targets from germanium (λ Кα = 1.256 Å), selenium (λ Кα = 1.106 Å), yttrium (λ Кα = 0.833 Å), molybdenum (λ Кα = 0.7107 Å), and silver (λ Кα = 0.5609 Å) were used.…”

“…Therefore, the screening parameters S for (1, 0) electrons of each atom can serve as fitting parameters when combining the experimental dependence with the calculated one. The calculated value is also corrected by the relativistic correction 5 and the correction for differences in the absorption of coherent and incoherent scattering 6 …”

“…A similar analytical dependence for the x range from 0.8 to 1.67 Å −1 can be obtained on the basis of experimental data by approximating functions of the form exp( a + bx ). In this case, for comparison with the theoretical dependence, it is necessary to introduce two minor corrections: the relativistic correction Q 5 and the correction M for the difference in the absorption coefficients of Compton μ С and Rayleigh μ R scattering 6 where φ and ψ are the angles of incidence and exit of radiation from the sample surface, respectively. Fitting such a corrected experimental dependence using Equations ) and () will make it possible to obtain the values of the parameters ( Z‐S ) j taking into account the interaction of electrons.…”