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Typical spectra of the K–M resonant Raman, Rayleigh and Compton scattered 59.536 keV c-rays by (a) Yb, (b) Lu and (c) Hf targets taken with the Si(Li) detector.
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The K-L and K-M resonant Raman scattering (RRS) cross-sections have been measured for the first time at the 59.536 keV photon energy in the 70Yb (BK=61.332 keV), 71Lu (BK=63.316 keV) and 72Hf (BK=65.345 keV) elements; BK being the K-shell binding energy. The K-L and K-M RRS measurements have been performed at the 59° and 133° angles, respectively,...
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The X-ray and gamma-ray radiation was registered in the moments of the maximum speed of current change (10 kA/ns) in the gas discharge tube. The collision of relativistic electrons with Krypton (Kr) and Xenon (Xe) as with metal vapor in the plasma discharge can intensify the X-ray emission due to their bigger atomic charge. Due to the freezing of h...
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... Various research groups used different excitation sources and techniques to evaluate the RRS cross-sections (Nakai et al., 2000;Karydas et al., 2002;Singh et al., 2004;Hunt et al., 2005;Kumar et al., 2007Kumar et al., , 2010Szlachetko et al., 2007) in various elements and their compounds. Nakai et al. (2000) examined the resonant Raman emission spectra of several Y compounds across the L 3 absorption edge of the element Y and found that only a resonant Raman peak was present in the spectra when the incident energy was slightly less than the absorption edge of Y while two peaks i.e. normal Lα emission peak along with RRS peak was observed for energies greater than the absorption threshold of Y. From their findings, they concluded that the electronic structure of the conduction band has a significant impact on the onset energy of the Lα emission line. ...
... They reported that the RRS was the reason behind these high values of cross-sections. Singh et al. (2004) used 59.54 keV photons for the measurements of K-L and K-M RRS cross sections for three elements with atomic numbers 70 ≤ Z ≤ 72 at a scattering angle of 59 • and 133 • on a reflection mode geometrical setup. It was observed that the K-L and K-M cross-section ratios for these elements were less than the fluorescent K-L and K-M X-ray transition probabilities up to ~45% and ~54%. ...
The present measurement illustrates the study of near-edge processes and the intensity ratios [ILl/ILα, ILβ1/ILα and ILl/ILβ1] for Mn Kα1,2 X-rays across the L2 edge of lanthanum in its various chemical forms viz., lanthanum oxide (La2O3), lanthanum oxalate (C6La2O12) and lanthanum acetate (C6H9LaO6) at four different scattering angles i.e. 90°, 105°, 115° and 125° with a lab-scale X-ray fluorescence (XRF) spectrometer. The current observation reveals that the Lβ1 X-ray emission lines exhibit a variance of ∼ (21–40) % between measured and calculated fluorescence cross-sections. Apart from this, the measured values of intensity ratios have been compared with the three data sets of calculated values using L shell emission rates based on the Dirac-Fock (DF) model, total X-ray emission rates and photoionization cross-section values based on the relativistic Hartree-Slater (RHS) model and three sets of Coster-Kronig (CK) and fluorescence yields. The correlation between crystal structure, bond distance and intensity ratio are also discussed in this work.
... At 4.140 keV (2 eV below the L 3 edge energy) the µ ( / ) expt value is found to be higher by about a factor of 2 than both the theoretical sets of values, whereas, at 4.700 keV (7 eV below the L 1 edge energy) was found to be higher by 36% and 41%, respectively, than both the µ ( / ) XCOM and the µ ( / ) Chant values. It is noteworthy that at photon energies just below an absorption edge (up to 25 eV-30 eV) the resonant Raman scattering (RRS) dominates (Sanchez et al., 2006;Karydas et al., 2002;Singh et al., 2004) and is expected to enhance the attenuation of X-rays. The structure just above the L 3 edge and in particular the presence of the white line due to allowed transition to unoccupied states below the continuum, as well as the broadening of the edge due to the core level lifetime is expected to produce major influence on the mass attenuation coefficients. ...
In the present work, the X-ray mass attenuation coefficients have been measured for 51Sb (a medium-Z element) at forty energies across its Li (i = 1–3) sub-shell absorption edges covering an extended energy region within 4.0 keV–14.0 keV. The aim of this study is to experimentally determine the key X-ray fundamental parameters for 51Sb with improved accuracy by using tunable energy synchrotron radiation. From the present measured mass attenuation coefficients, the Li (i = 1–3) sub-shell photoionization cross sections (σLiP) have been deduced at twenty four energies across the Li (i = 1–3) edge-energies of 51Sb covering the region 4.150 keV–5.0 keV by using experimentally deduced Li (i = 1–3) edge jump ratios. Two theoretical datasets of X-ray mass attenuation coefficients and total photoionization cross sections were served to evaluate their consistency with the present experimental values and reveal possible discrepancies, in particular, across the Li (i = 1–3) edge-energies of 51Sb.
... It is worth mentioning that at incident photon energies in vicinity of the K-shell / Li / Mi sub-shell absorption edge energies for a given element, near-edge processes such as X-ray Absorption Fine Structure (XAFS) and the Resonant Raman Scattering (RRS) can contribute significantly to the mass attenuation coefficients. The XAFS occurs up to about 100-200 eV above the edge (Bianconi, 1988;Rehr, 2006), whereas the RRS at incident energies up to few tens of eV below the edge ( Sanchez, 2006;Karydas, 2002;Singh, 2004). It may be noted that the contribution of these near-edge processes have not been included in the existing theoretical tabulations (McMaster et al., 1970;Storm et al., 1970;Veigele, 1973;Berger et al., 2010;Chantler, 1995Chantler, , 2000Creagh et al., 1992) of the mass attenuation coefficients. ...
... At photon energies, E L1 < E≤14.0 keV, the measured values are higher than the two sets of theoretical values (Berger et al., 2010;Chantler, 1995) by 5-10%. It is worth noting that at photon energies just below an absorption edge (up to 25-30 eV) the resonant Raman scattering (RRS) dominates (Sanchez, 2006;Karydas, 2002;Singh, 2004) and is expected to enhance the attenuation of X-rays, whereas, at energies few eV above the edges the X-ray absorption fine structure (XAFS) creates strong modulations in the photoelectric absorption process. The near-edge structures (from around 20 eV below to 20 eV above the absorption edge) such as the white line emerged due to allowed transition to unoccupied states below the continuum, as well as the broadening of the edge due to the core level lifetime have the highest influence on the mass attenuation coefficient (more than a factor of two in case of white line), which is also evident from the L 3 edge jump ratio. ...
The absolute values of the mass attenuation coefficients have been measured at sixty two photon energies across the Li (i=1–3) sub-shell absorption edges of 66Dy covering the region 7.6–14.0 keV in order to investigate the influence of near-edge processes on the attenuation coefficients. The present measured attenuation coefficients are found to be higher by up to 10% than the theoretical values evaluated from the computer code XCOM (Berger et al., 2010) and the self-consistent Dirac-Hartree-Slater (DHS) model based values tabulated by Chantler (1995) over the energy region 7.6–14.0 keV, except at energies in vicinity (few eV) of the Li (i=1–3) sub-shell absorption edge energies where the measured values are significantly higher (up to 37%) than both the sets of theoretical values. Further, the Li (i=1–3) sub-shell photoionization cross sections, , deduced from the present measured mass attenuation coefficients are compared with the non-relativistic Hartree-Fock-Slater (HFS) model based values tabulated by Scofield (1973) and those evaluated from the theoretical total photoionization attenuation coefficients tabulated by Chantler (1995). The deduced (i=1–3) values are found to be in better agreement with those evaluated from the tabulations given by Chantler (1995) than the values given by Scofield (1973) over the energy region 7.8 – 14.0 keV included in this study. However, at photon energies up to few eV above the Li edges, the deduced (i=1–3) values are found to be significantly higher (up to 32%) than both the sets of theoretical values.
... More information about the fine structure of radiative RRS (Nakai et al., 2000) can be obtained from high resolution Auger electron resonant Raman technique (Ichikawa et al., 1992;Baba et al., 1994). Recently, modest resolution energy dispersive X-ray fluorescence (EDXRF) setups involving radioisotope (Singh et al., 2004;Kumar et al., 2007;Sharma et al., 2008) and particle-induced X-ray emission (Karydas et al., 2002b) based photon sources have also been used for radiative RRS measurements. The RRS process becomes more predominant near ionization threshold and leads to significant contribution to the attenuation coefficients. ...
The KL2,3 and L3M4,5 radiative resonant Raman scattering (RRS) cross sections have been measured for the quasimonochromatic Mn Kα1,2 X-rays (5.895 keV) in 24Cr (K-shell level width (ΓK) = 1.08 eV) and 59 Pr (L3-subshell level width (ΓL3) = 3.60 eV), respectively, using targets in metallic and various chemical forms. The incident Mn Kα1,2 X-ray energy is lower than the K-shell binding energy of 24Cr and L3-subshell binding energy of 59Pr by ~94 ΓK (Cr) and ~94 ΓL3 (Pr), respectively. The experimental measurements were performed with a low energy Ge detector (LEGe) and a radioactive ⁵⁵Fe annular source in conjunction with 24Cr absorber. The measured cross section values for the 24Cr and 59 Pr elements in their various oxidation states are found to be same within experimental errors. The measurements were further extended to investigate alignment of the intermediate L3-subshell (J = 3/2) virtual vacancy states in 59Pr through angular distribution measurements for RRS photon emission, which is found to be isotropic within experimental errors.
In this work we present theoretical calculations of the resonant Raman scattering contributions to the background of X-ray fluorescence spectra. The main goal of the paper is to obtain a simple and reliable procedure to calculate the influence of RRS in spectrochemical analysis by X-ray fluorescence including second order enhancement processes. In order to perform the calculations, the Shiraiwa and Fujino model was used to calculate the characteristic intensities of the different atomic processes involved. In the case of polychromatic excitation over a multi-element sample of proximate atomic numbers, the calculations show that the contribution of RRS is higher than Compton scattering but lower than coherent scattering, this last process being the most important source of background in the range of the fluorescent lines. The calculated effects of enhancements are rather low and have influence only on the lightest elements of the spectra. On the other hand, the resonant Raman scattering line interferes with fluorescent peaks in the case of monochromatic excitation when elements of proximate atomic numbers are analyzed (for example Al–Si). The model proposed here allows the analysis of the different sources of background, which contribute to a better understanding of the physical processes involved in the different techniques of XRF analysis. In addition, the calculations presented here can contribute significantly to a more precise quantification of traces and minor components.
X-ray fluorescence spectra present singular characteristics produced by the different scattering processes. When atoms are irradiated with incident energy lower and close to an absorption edge, scattering peaks appear due to an inelastic process known as resonant Raman scattering. It constitutes an important contribution to the background of the fluorescent line. The resonant Raman scattering must be taken into account in the determination of low concentration contaminants, especially when the elements have proximate atomic numbers. The values of the mass attenuation coefficients experimentally obtained when materials are analysed with monochromatic x-ray beams under resonant conditions differ from the theoretical values (between 5% and 10%). This difference is due, in part, to the resonant Raman scattering. Monochromatic synchrotron radiation was used to study the Raman effect on pure samples of Mn, Fe, Cu and Zn. Energy scans were carried out in different ranges of energy near the absorption edge of the target element. As the Raman peak has a non-symmetric shape, theoretical models for the differential cross section, convoluted with the instrument function, were used to determine the RRS cross section as a function of the incident energy.
The atomic inner-shell vacancy decay processes comprising of radiative and non-radiative transitions are characterized by the physical parameters, namely, the photoionization cross-sections; X-ray, Auger and Coster–Kronig (CK) transition rates; fluorescence and CK yields; and the vacancy transfer probabilities. These parameters are required to calculate the K-shell and Li (i = 1–3)/Mi (i = 1–5) sub-shell X-ray production cross-sections and relative intensities which, in turn, are needed for different analytical applications. This report intended to provide a detailed account of the currently available data sets of different physical parameters for use in various analytical applications. Copyright © 2011 John Wiley & Sons, Ltd.
Monochromatic synchrotron radiation was used to study the Raman effect on pure samples of Mn, Fe, and Cu and on oxides such as Mn2O3, Fe2O3, CuO and Cu2O. Energy scannings were carried out for different ranges of energies near the absorption edge of the target element. Theoretical models for the energy distribution of the Raman scattered photons, convoluted with the instrument function, were used to determine the resonant Raman scattering (RRS) cross sections as a function of the incident energy. The results indicate that RRS cross sections for pure samples are similar to those for oxides for the same energy difference from the respective edge, showing that the Raman scattering takes place in the same way in both kinds of samples. Copyright © 2008 John Wiley & Sons, Ltd.
We present a review of our recent measurements of large angle elastic and inelastic scattering differential cross-sections in the photon energy range 14–88 keV (momentum transfer ranging 1.135 to 6.310 Å−1 covering large number of elements in the atomic region Z=1–92, with special emphasis on the elements having K/Li shell/subshell binding energy in the vicinity of the incident photon energy. These measurements were performed using energy dispersive X-ray fluorescence (EDXRF) setup involving radioisotope as a photon source and a solid-state photon detector arranged in an annular geometry. The measured scattering differential cross-sections were compared with the theoretical values based on the state-of-art relativistic second order S-matrix calculations and those based on the form factor approximations in order to check their reliability. The KL and KM resonant Raman scattering (RRS) at 59.54 keV incident photon energy was also investigated for some heavy elements.
The Rayleigh, Compton and K-shell radiative resonant Raman scattering cross-sections for the 88.034 keV γ-rays have been measured in the 83Bi (K-shell binding energy = 90.526 keV) element. The measurements have been performed at 130° scattering angle using reflection-mode geometrical arrangement involving the 109Cd radioisotope as photon source and an LEGe detector. Computer simulations were exercised to determine distributions of the incident and emission angles, which were further used in evaluation of the absorption corrections for the incident and emitted photons in the target. The measured cross-sections for the Rayleigh scattering are compared with the modified form-factors (MFs) corrected for the anomalous-scattering factors (ASFs) and the S-matrix calculations; and those for the Compton scattering are compared with the Klein-Nishina cross-sections corrected for the non-relativistic Hartree-Fock incoherent scattering function S(x, Z). The ratios of the measured KL2, KL3, KM and KN2,3 radiative resonant Raman scattering cross-sections are found to be in general agreement with those of the corresponding measured fluorescence transition probabilities.
