洞态Ar原子K_α和K_β伴线和超伴线的理论计算

基于全相对论多组态Dirac-Fock方法,对L壳层旁观空穴下Ar原子退激衰变辐射K-X射线K_(α1,2)(K→L_(3,2))和K_(β1,3)(K→M_(3,2))的6908条伴线和超伴线跃迁能、跃迁概率进行了系统计算,计算结果与文献已有数据比较具有很好的一致性.通过对(K~(-1)L~(-1),l=0-8)伴线和(K~(-2)L~(-l),l=0-8)超伴线跃迁谱线卷积得了其合成谱,给出了L壳层不同空穴数下K-X射线伴线和超伴线的平均能量和平均跃迁强度.结果表明,退激辐射X射线能量以及能移与L壳层空穴个数呈现明显的线性关系.基于结论,进一步给出了跃迁能移与L壳层空穴个数之间的关系表达式.研究结果可以为解释离子、原子碰撞过程中产生的X射线谱提供重要的理论支持.     

A study of KαL1 X‐ray satellite spectrum of the elements 27 ≤ Z ≤ 31 by photon excitation

K _α X‐ray satellite spectra of Co, Ni, Cu, Zn, and Ga generated by photon excitation are analyzed using a wavelength dispersion spectrometer. Spectra of Ni, Cu, Zn, and Ga are studied for the first time using a LiF420 crystal. Spectrum of Co was studied with LiF200 crystal in second order. K_αL¹ X‐ray satellite energies and relative intensities are measured. The energy shifts relative to diagram line are computed and are compared with theoretical and semi‐empirical values. Dependence of energy shifts and relative intensities on Z and mode of excitation is analyzed.     

Chemical effects on beryllium K X-ray spectra produced by heavy ion bombardment

Beryllium X-ray spectra from Be and BeO targets by proton, helium, nitrogen and argon ion bombardment have been measured. In the oxide, chemical shifts of K_α and K²_α X-ray lines are similar magnitude and the intense satellite KL and hypersatellite K²L lines are observed by heavy ion bombardment.     

Energies and relative intensities of Kα3 and Kα4 x‐ray satellites of sulfur and sulfides by photon excitation

Energies and relative intensities of the K x‐ray satellites K_α4 and K_α3 of sulfur and two sulfides K₂S and FeS are measured by a wavelength dispersive spectrometer. The energy shifts of these satellites relative to the diagram line are compared with Dirac–Fock theoretical values. The energy shifts and relative intensities are examined for chemical effects. Supplementing the present data to the available data, Z dependence of K_α4/K_α3 intensity ratio is studied in the low Z region. Copyright © 2007 John Wiley & Sons, Ltd.     

Shifts of X-ray characteristic L lines of free atoms of rare-earth metals

Results of the study of X-ray characteristic spectra of free atoms of a number of rare-earth metals from Ce to Ho are reported. L _α1 and L _β1 lines were studied, and the shifts of the peaks of emission lines of free atoms relative to their positions in the case of emission by the solid aggregate state were measured. The data obtained enable one to use the corresponding X-ray characteristic lines as references with the accuracy Δλ/λ≈10^?5. The Z-dependences of shifts are plotted.     

Total attenuation cross-sections of fluorescent X-rays of Zr,Sn, Ba,Au, Pb,Th and U in elements 6⩽Z⩽82

The total attenuation cross-sections in elements 6?Z?82 forK _α andK _β groups of lines of elements Zr, Sn and Ba andL _l ,L _α,L _β andL _γ groups of lines of the elements Au, Pb, Th and U have been measured. The experimentally measured attenuation cross-sections have been found in good agreement with the theoretical estimates.     

Kα X-ray satellite spectra of Ti, V, Cr and Mn induced by photons

K X-ray emission spectra of Ti, V, Cr and Mn generated by photon excitation have been studied with a crystal spectrometer. The measured energy shifts of K_α satellite relative to the diagram line are compared with values obtained by electron excitation and with different theoretical estimates. The present experimental values of K_αL¹/K_αL⁰ relative intensities are compared with values obtained by electron excitation.      

2p3/2−13x−1–3x−13d3/2−1 x‐ray satellites in the Lα2 region

The energies and intensities of the various transitions corresponding to the transition scheme 2p_3/2^?13x^?1–3x^?13d_3/2^?1 (i.e. L₃M_x–M_xM₄) were used to compute theoretical Lα₂ satellite spectra in 13 elements in the atomic number range of 62 ≤ Z ≤ 90. The energies were calculated using available HFS data on K–LM and L–MM transition energies. The intensities of all the possible transitions were estimated by considering cross‐sections for the Auger transitions simultaneous to a hole creation and then distributing statistically the total cross‐sections for initial two‐hole states 2p_3/2^?13x^?1 (L₃M_x) amongst various allowed transitions from these initial states to 3x^?13d_3/2^?1 (M_xM₄) final states. Each transition was assumed to give rise to a Gaussian line and the overall spectrum was computed as the sum of these Gaussian curves. The calculated spectra were compared with the available measured Lα satellite spectra. The peaks in the theoretical satellite spectra were identified as the experimentally reported satellites Lα_s, La₁₃, La₁₄ and La₁₇, which lie on the high‐energy side of the Lα₂ dipole line. Copyright © 2005 John Wiley & Sons, Ltd.     

Chemical shift of the Ga and As Kα1,2 and Kβ1,3 X-ray emission lines

By means of a double crystal spectrometer and a computer the chemical shifts of the Ga Kα_1,2, As Kα_1,2 and Kβ_1,3 lines were determined with high accuracy. An interpretation of the results obtained with a free ion model and a calculation according to the Hartree method shows agreement of the values calculated for the effective atomic charges with those based on chemical experience, and also the presence of a charge transfer from the A atom to the B atom in A^IIIB^V compounds. The existence of binding charges is one of the reasons for the fact that |q_A| ≠ |q_B|. The interpretation of the Kβ_1,3 and Lα shifts shows the limitations of the free ion model.     

Kβ X-ray emission from He-like ions

Relativistic calculations on the energies and electric dipole rates of K_β X-rays from 1s3p(¹P₁,³P₁)-1s² (¹S₀) transitions for He-like ions in the range Z=14–54 are carried out using multi-configuration Dirac–Fock (MCDF) wave functions in the active space interaction approach. The contributions from Breit interaction and quantum electrodynamics have also been included in the calculation. An attempt has been made to find a scaling expression for Breit energy in terms of Zα .The scaled Breit energies are in good agreement with the earlier accurate relativistic results and this ensures the reliability of our scaling procedure. The behavior of MCDF wavefunctions for a given J in the non-relativistic limit has also been studied. The calculated K_β X-ray energies and rates agree well with other available experimental and theoretical values.     

X‐ray fluorescence determination of sulfur chemical state in sulfide ores

This paper describes the X‐ray fluorescence technique for estimation of the ratio between sulfide and total sulfur in sulfide ores using the influence of sulfur chemical state on positions and intensities of lines (SKα_1,2, SKβ_1,3) and satellites (SKβ′, SKα_3,4) of the sulfur X‐ray emission spectra measured by the wavelength‐dispersive X‐ray fluorescence spectrometer. The samples to be analyzed were prepared as pressed powder pellets on boric acid substrate. The SKα_1,2 line chemical shift is the most appropriate parameter for sulfur chemical state estimation because spectral lines in this field are intensive and are almost not affected by spectral overlap of lead spectrum lines. The ratios of line intensities SKβ′/SKβ_1,3, SKα_3,4/SKα_1,2 and SKβ_1,3/SKα_1,2 were also used as analytical parameters. Forty‐one samples of sulfide ores collected in the Russian Far East and Southern Ural deposits have been analyzed. The results of estimation of sulfur chemical state by gravimetric and proposed X‐ray fluorescence techniques agree fairly well. Copyright © 2016 John Wiley & Sons, Ltd.     

K X-ray satellite structures of bromine and molybdenum

The energies and electric dipole rates of Kα X-ray satellites due to 1s-2p transitions in bromine and molybdenum with one to five vacancies in the 2p shell and other shells retaining their normal occupation numbers are computed using Multi-Configuration Dirac Fock wavefunctions with the inclusion of relativistic and quantum electrodynamic corrections. As fully relativistic calculations on all the Kα X-ray fine structure satellites with multiple spectator vacancies in the 2p shell of elements under consideration, to the best of our knowledge, are reported in this work for the first time, the accuracy of the E1 data is analyzed in terms of the agreement between the rates in the length and velocity forms. While the intensities of the strong electric dipole lines in the various groups of 1s - 2p transitions obey the well established Z dependence, many of the weak transitions vary randomly with Z and an attempt is made in this work to understand the behaviour of the spin-forbidden and weak electric dipole lines in the KαL ⁿ X-ray satellite structure of Br, Mo, I, and Au. As the number of closely spaced fine structure transitions range from a few to many depending on the spectator vacancies in the 2p shell, the intensity weighed statistical average satellite energies, line strengths and photo-ionization cross sections are reported to guide in the reliable interpretation of experimental measurements.     

Lβ2 satellites in the X‐ray emission spectra of elements 72Hf, 73Ta, 74W, 81Tl, 83Bi and 92U

The satellite spectra arising due to the L₃M_x–M_xN_4,5 (x = 1–5) transition array in the X‐ray emission spectra of ₇₂Hf, ₇₃Ta, ₇₄W, ₈₁Tl, ₈₃Bi and ₉₂U have been calculated using available HFS data on K–LM and L–MN Auger transition energies. The agreement between the calculated and measured energies, that between calculated and measured separations in energies and the consideration of the relative probabilities of all the L₃M_x–M_xN_4,5 transitions have been used as the basis for deciding the origin of the satellites. It has been established that two satellites observed in the Lβ₂ region of the X‐ray spectra of various elements, named β₂^I and β₂^II in the order of increasing energy, are mainly emitted by the L₃M_4,5–M_4,5N_4,5 transitions. It is observed that satellite β₂^I in the spectra of elements with ₇₂Hf to ₇₄W has been assigned to the superposition of the ³F₄–³G₅ and ³F₄–³D₃ transitions and must be the most intense one among all these satellites. The same transition has been proved to be the main origin of satellite β₂^II, reported in the element with ₈₁Tl, ₈₃Bi and ₉₂U. Further, satellite β₂^I, reported in the spectra of elements with ₈₁Tl and ₉₂U, has been associated with the transitions ³D₃–³F₄ and ¹D₂–¹F₃. Finally, line β₂^II, reported in the spectra of elements with Z = 72–74, has been assigned to the ¹F₃–¹G₄ and ³P₀–³D₁ transitions. The possible contributions of other transitions of the L₃M_x–M_xN_4,5 (x = 1–5) array having intensities comparable with those of the above transitions, as well as the corresponding lines that have not yet been observed, have also been discussed. Copyright © 2011 John Wiley & Sons, Ltd.     

Al satellite transition spectroscopy (SATRAS) of polycrystalline aluminium borate 9Al2O3 · 2B2O3

²⁷Al NMR spectra of polycrystalline aluminium borate 9Al₂O₃ · 2B₂O₃ have been measured at 104, 130 and 156 MHz. The parameters of the quadrupole interaction and the isotropic chemical shifts have been obtained by fitting the CT/MAS pattern and consideration of the inner satellite transitions m = 3/2 ↔ 1/2 and m = −1/2 ↔ −3/2. The gain in spectral resolution concerned with the observation of the MAS lines of the inner satellites leads to complete separation of the signals of AlO₆, AlO₅ and AlO₄ polyhedra. Also signals of structural groups of one and the same coordination number can be distinguished. Experimental and theoretical lineshape calculations are compared.     

Diagram,valence-to-core,and hypersatellite Kβ X-ray transitions in metallic chromium

We report on measurements of the Kβ diagram, valence-to-core (VtC), and hypersatellite X-ray spectra induced in metallic Cr by photon single and double K-shell ionization. The experiment was carried out at the Stanford Synchrotron Radiation Lightsource using the seven-crystal Johann-type hard X-ray spectrometer of the beamline 6-2. For the Kβ diagram and VtC transitions, the present study confirms the line shape features observed in previous works, whereas the K^hβ hypersatellite transition was found to exhibit a complex spectral line shape and a characteristic low-energy shoulder. The energy shift of the hypersatellite relative to the parent diagram line was deduced from the measurements and compared with the result of extensive multiconfiguration Dirac–Fock (MCDF) calculations. A very good agreement between experiment and theory was found. The MCDF calculations were also used to compute the theoretical line shape of the hypersatellite. A satisfactory agreement was obtained between the overall shapes of the experimental and theoretical spectra, but deviations were observed on the low- and high-energy flanks of the hypersatellite line. The discrepancies were explained by chemical effects, which were not considered in the MCDF calculations performed for isolated atoms.     

Direct inner shell ionization accompanying nuclear fusion reactions with heavy ions

Probabilities for K-shell ionization prior to fusion (half-trajectory collisions) are determined for ⁵¹V, ⁵⁹Co, ⁶²Ni target atoms and 4.5 MeV/u ⁴⁰Ar projectiles. Also measured are energy shifts of the K_α and K_β X-ray lines of residue atoms resulting from multiple inner shell ionization.     

Chemical shifts in strontium compounds by X-ray spectroscopy

The positions of the X-ray K-absorption edge of strontium in various compounds and in aqueous solutions have been measured. With the help of modified Moseley diagram the wavelength of the X-ray K-absorption edge of Strontium in metal has been extrapolated. Chemical shifts of the K-absorption edge with respect to this extrapolated value have been presented. The fine structure has been observed on the high energy side of the main absorption edge both in Rubidium and Strontium compounds. Bond lengths for various compounds have been calculated from the maxima-minima separations. The chemical shifts of fluorescence Kα_1,2 lines with respect to their position in Sr²⁺ ion have also been studied. While the edge shift with respect to the edge in free ion is towards the low energy side, the line shift with respect to the line in free ion is towards the high energy side.     

Study of chemical shift in Ll and Lƞ X‐ray emission lines in different chemical forms of 48Cd and 50Sn compounds using WDXRF technique

Chemical shift in Ll and L? X‐ray emission lines of ₄₈Cd and ₅₀Sn elements in various chemical compounds was determined with high resolution wavelength dispersive X‐ray fluorescence (WDXRF) spectrometer. The positive and negative shifts were measured in ₄₈Cd compounds viz, CdS, CdB₄O₇, CdCl₂, Cd₃(PO₄)₂, CdCO₃, CdI₂ and CdO with reference to pure Cd foil and ₅₀Sn compounds viz, Sn(CrO₄)₂, SnO, SnO₂, SnCl₂, SnF₂, SnF₄ with reference to pure Sn foil. The measured energy shifts in Ll X‐ray emission lines range from ?0.47 to 1.82 eV and L? emission lines range from ?2.67 to 1 eV for both compounds. The effective charges (q, q ^/ , q ^// , and q ^/// ) were calculated from four models (Pauling method, Suchet method, Levine method and Batsonav method) and found to be linear dependence with chemical shift. The measured chemical shifts were correlated with effective charge, number of ligands and electronegativity of the central metal atom in the given compounds.     

X-ray emission spectra and electronic structure of VO,VN, VC

The experimental K_β5 and L_α emission spectra for vanadium and K_α spectra for nonmetal are studied for vanadium monoxide, nitride and carbide. Using the spectra unfolding the experimental molecular orbital diagrams have been obtained. By the semiempirical Mulliken-Wolfsberg-Helmholz method with the self-consistency on charges and configurations the calculations of electronic structure of clusters [VO₆]^10?, [VN₆]^15? and [VC₆]^20? have been carried out. The results of calculations are compared with the X-ray data. The effects of chemical bonding and charge densities on metal atoms in VO, VN, VC are discussed.     

Empirical,Semi-Empirical and Experimental Determination of K X-Ray Fluorescence Parameters of Some Elements in the Atomic Range 21 ≤ Z ≤ 30

In this study, the semi-empirical and empirical calculations of K X-ray intensity ratios, K-shell fluorescence yields, and vacancy transfer probabilities have been performed for 3d transition elements. Also, σ_Kα, σ_Kβ production cross-sections, K_β/K_α intensity ratios, ω_K fluorescence yields, and η_KL vacancy transfer probabilities of 3d transition elements have been measured. The samples were excited by 59.5 keV γ-rays from a ²⁴¹Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV.