Resonant Raman scattering of polarized and unpolarized x-ray radiation from Mg, Al, and Si

Abstract

The x-ray resonant Raman scattering (RRS) effect of polarized and unpolarized radiation in the vicinity of the 1s absorption threshold of low-Z elements such as magnesium, aluminum, and silicon is investigated. For the polarized and tunable exciting x-ray radiation the plane grating monochromator (PGM) beam line at the PTB laboratory in the BESSY II synchrotron radiation facility was employed, while unpolarized x-ray beams were induced by 1-MeV proton beam irradiation on various pure thick targets. For the latter case, a novel proton-induced x-ray fluorescence scattering chamber was designed and installed at the Tandem accelerator laboratory of the Institute of Nuclear Physics at N.C.S.R. "Demokritos." The total RRS cross sections deduced from both independent excitation modes were found to be in a good agreement, within the experimental uncertainties. The predictions of the existing theory with respect to the dependence of the RRS to the incident beam polarization state is calculated and discussed with respect to the experimental results.

Nonresonance Compton scattering of an X-ray photon by a Ni-like atomic ion

“…Figure 2 presents the calculated values (in percent) of relative contributions of l harmonics of the n 1 l 1 → εl transition channel to the total cross section of non resonance Compton scattering of a photon by a n 1 l 1 shell of the ions in question: (16) In (16), the quantity is defined by expressions (7) (n 1 l 1 = 3p) and (10) (n 1 l 1 = 3d) for a fixed harmonic l of transition and the value of scattered photon energy is taken at the maximum of the Compton profile. One can see that, for 3p(3d) → εl scattering channels (anal ogous data for the 1s, 2s, 2p, and 3s shells are not pre sented here), the leading harmonics are concentrated in the region close to l = 3 as the nuclear charge of the ion increases.…”

“…It was also found that, on increasing the nuclear charge of a Ni like ion, the integral intensity of nonresonance Compton scat tering is redistributed (a) toward the longer wavelength region of scattering spectrum in terms of the energy of a scattered photon and (b) toward the energy region of resonance Landsberg-Mandelstam-Raman scatter ing before the line of elastic Thomson and Rayleigh scattering, i.e., to the region which is experimentally unattainable with the modern level of spectral resolu tion. We believe that, in future experiments on scatter ing of an X ray photon by an atomic ion, the absolute values and the shape of the double differential cross section of scattering of a photon by a Ni like atomic ion will be measured with a high accuracy (the error of measurement of the scattering cross section is about 10% already in modern experiment [16]) and the lead ing role of the d symmetry of a core in the formation of probability of inelastic Compton scattering in the energy region (which is quite expected) will be confirmed.…”

Proton induced quasi-monochromatic x-ray beams for soft x-ray spectroscopy studies and selective x-ray fluorescence analysis

“…17 Further studies that have been favoured are related to the determination of absolute cross section of the resonant Raman scattering of low Z atoms. 18 The resonant Raman scattering besides the profound atomic physics related interest has also a significant importance for the precision on the quantitative XRF analysis of impurities. For instance, when optimized synchrotron XRF analysis of Z − 1 or Z − 2 impurities into Z-based matrices is required by tuning the incident beam energy below the absorption edge of Z element, the strong Z-dependent RRS signal affects considerably the lower detection limits.…”

“…The advantages for such an x-ray source are mainly related to the high inner shell ionization cross sections of heavy ions, and most important with the very low emission, compared to electrons, of bremsstrahlung radiation as the ions decelerate into matter resulting in an improved peak to background ratio. 1 The concept of the proton-induced monochromatic x-ray beams [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] has been utilized in the past in various spectroscopy and analytical studies related with the determination of impurities or minor elements in pure metal matrices, [8][9][10][11][12] as well as for inelastic x-ray scattering experiments in experimental conditions (exciting x-ray beam energy, atomic number of the target element) that favour the study of x-ray resonant Raman scattering (RRS) [13][14][15][16] and more recently for the production of soft keV micro-focused x-rays for single cell irradiation allowing for a more consistent dose delivery. 19 Here, through the development of an integrated x-ray spectroscopy end station, we describe the dynamic utilization of the advantages of proton-induced x-ray beams when used for soft x-ray spectroscopy applications and especially for XRF analytical purposes.…”

Nonresonance Compton scattering of an X-ray photon by an atom with the core of the d symmetry

“…Moreover, these approximations do not take into account the effect of a substantial multipolarity of each partial scattering channel ( ) , which was previously ascertained in [19,20] and was confirmed in this work and which fundamentally determines the magnitude and direc tionality of the probability redistribution of inelastic scattering of a photon by the atom. We can assume that future experiments on scattering of an X ray photon by the atom will make it possible to measure with a high accuracy (even in modern experiments, the measurement error of the scattering cross section is ~2-5% [23,24]) the absolute values and the shape of the double differential scattering cross section of a photon by the Zn atom and to confirm the (quite expected) fact of the leading role played by the d symmetry of the core in the formation of the prob ability of inelastic scattering in the energy range .…”