Calculation of vacancy transfer probabilities from K to L shell using the X-ray fluorescence parameters

The probabilities for vacancy transfer from the K to the L shell (η_KL), have been calculated for eleven high atomic number elements using the measured K and L shells X-ray production cross-sections. The targets were excited by 123.6 keV photon from a ⁵⁷Co annular radioactive source. K and L X-rays emitted by samples were counted with a Si(Li) detector. The measured values of η_KL were compared with the theoretical values and our early papers.     

Chemical effects on K and L shell production cross sections and transfer probabilities in Nb compounds

In this study, the chemical effects on σ_Ki (i = α, β), σ_Lα cross sections, K_β/K_α X-ray intensity ratios and vacancy transfer probabilities from K to L (η _KL) for pure Nb and Nb compounds were investigated. The samples were excited by 59.5 keV γ-rays from ²⁴¹Am and 5.96 keV photon energy from a ⁵⁵Fe annular radioactive sources. K and L X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. While it was observed that the chemical bonding had an effect on the σ_Kβ, σ_Lα cross sections and K_β/K_α X-ray intensity ratios for compounds, it was almost negligible for σ_Kα cross section because K_α transitions (2P_3/2,1/2→1S_1/2) occurred in inner shells. It is well known that interactions between central element atom and ligands come into existence in valence state, so outer energy levels are sensitive to the chemical environment. The experimental values of σ_Kα cross section and η _KL are in good agreement with theoretically calculated and other experimental values of pure niobium, but the experimental values of the σ_Kβ, σ_Lα cross sections and K_β/K_α X-ray intensity ratios have differences for some compounds because valence electrons have different bond distances and binding energies in different compounds.     

L X-ray production cross sections, average L shell fluorescence yield and intensity ratios in heavy elements

L X-ray fluorescence cross sections, and intensity ratios were measured for elements in the 70￡Z￡92 atomic range at the excitation energy 59.5 keV using a Si(Li) detector. Furthermore, L X-ray fluorescence cross sections and intensity ratios were calculated for elements in the same range. The average L shell fluorescence yields were derived using experimental L X-ray fluorescence cross sections and theoretical photoionization cross sections. The obtained results were compared with other experimental and theoretical values. This revised version was published online in August 2006 with corrections to the Cover Date.     

Measurement of L x-ray production cross sections by 60 keV photons and average L shell fluorescence yields of lanthanides

L x-ray production cross sections have been measured for lanthanides with 60 keV. The measured L x-ray production cross section values for the lanthanides are in good agreement with the theoretical ones evaluated using L _i subshell fluorescence yields ω_i, Coster-Kronig transition probabilities ? _ij based on the Relativistic-Hartree-Slater theory, K to L _i subshell vacancy transfer probabilities n _KLi, fractions of the ratiative width of the subshell F _ny and L _i subshell photoionisation cross section σ_Pi. The average L shell fluorescence yields ω_L have also been derived using the presently measured total L x-ray production cross section values and the theoretical K to L shell vacancy transfer probabilities. These results are compared with theoretically predicted values.     

Measurement of vacancy transfer probabilities from K to L shell for high atomic number elements

The probabilities for vacancy transfer from K to L shell, η_KL, were obtained by measuring the K_β/K_α intensity ratios in 25 elements over the range 57 ≤ Z ≤ 92 using a 25 mCi ⁵⁷Co filtered source for excitation. The K X-rays were measured by using a Si(Li) detector. The theoretical values were calculated via the radiative and radiationless transition rates of these elements. The comparison between present experimental results and theoretical predictions showed that both results agreed well. The experimental and theoretical values were fitted against atomic number (Z). The measured values of η_KL for Tm, Yb, Lu, Hf and Ir are being reported here for the first time.     

Alloying effect on K to L shell vacancy transfer probabilities in 3d transition metals

The alloying effects on K to L shell vacancy transfer probabilities (η_KL) in 3d transition metals have been carried out by X-ray fluorescence studies of various alloy compositions. K X-ray intensity ratios of Ti, Cr, Fe, Co, Ni, and Cu elements in the Fe_xNi_1?x, Fe_xCr_1?x, Ni_xCr_1?x, Fe_xCr_yNi_1?(x+y), Ti_xNi_1?x, Ti_xCo_1?x, and Co_xCu_1?x alloys have been measured following excitation by 22.69 keV X-rays from a 10 mCi ¹⁰⁹Cd radioactive point source and η_KL values for alloying elements have been determined from these ratios. The spectrum of characteristic K-X-ray photons from samples were detected with a high resolution Si(Li) detector coupled to a 4 K multichannel analyzer. The present investigation makes it possible to perform reliable interpretation of experimental K to L shell vacancy transfer probabilities for various 3d transition metals in alloys and can also provide quantitative information about the changes of K to L shell vacancy transfer probabilities of these metals with alloy composition.     

Measurement of K shell fluorescence cross sections and K shell fluorescence yields for the atomic region 22≤Z≤64 by 59.5 keV photons

A new method has been developed to determine K shell fluorescence cross section and K shell fluorescence yields. This method is based on simultaneous measurement of fluorescence radiation and scattered radiation, thus avoiding problems with measuring the source strength and source-to-detector solid angle. The K shell fluorescence cross section and K shell fluorescence yield for 21 elements in the atomic range 22£Z£64 have been measured by using a Si(Li) detector. The obtained results are compared with the other experimental, theoretical and fit values.     

Measurements of K X-ray fluorescence cross sections of Fe,Co, and Ni in an external magnetic field

The effects of the external magnetic field has been investigated on the K XRF cross sections of Fe, Co, Ni, and some of their compounds by using an energy dispersive X-ray fluorescence spectrometer. The samples were irradiated by using the γ-rays of 59.537 keV emitted from an ²⁴¹Am radioisotope source of 100 mCi. The samples were prepared from pure foil of Fe, Co, Ni, and some of their compounds. The external magnetic fields have been applied two opposite directions and the magnitude of the external magnetic field has been fixed at 0.400 T and −0.400 T. The measured K XRF cross sections have been compared with the calculated theoretical data and interpolated values of Puri et al. Our experimental results show that the K XRF cross sections have been affected by the external magnetic field.     

Measurement of Cu K and Ag,In and Sn L X-ray production cross sections by low-energy positron impact

Cu K and Ag, In and Sn L X-ray production cross sections by positron impact have been determined experimentally in the energy range below 30 keV using an X-ray detector with thin Si(Li) crystals. These values have been compared with theoretical estimates derived using the binary encounter formalism. The values for Cu K and Ag L X-rays have also been compared with the results of theoretical calculations using the plane-wave Born approximation with Coulomb and relativistic corrections.     

K X-ray production cross sections for 40-180 keV protons

Considering the importance of the X-ray production cross sections for the determination of the element concentrations in a given material, we have measured them experimentally for Al Si, Sc, Ti, V, Fe, Co, Ni and Cu bombarded by protons with energies ranging from 40 to 180 keV. This revised version was published online in July 2006 with corrections to the Cover Date.     

Analytical formulas for calculation of K X-ray production cross sections by alpha ions

In the present study, different procedures are followed to deduce the semi-empirical and the empirical K X-rayX-ray production cross sections induced by alpha ions from the available experimental data and the theoretical results of the ECPSSR model for elements with 20≤Z≤30. The deduced K X-ray production cross sections are compared with predictions from ECPSSR model and with other earlier works. Generally, the deduced K X-ray production cross sections obtained by fitting the available experimental data for each element separately give the most reliable values than those obtained by a global fit.     

Measurement of K shell radiative transition probabilities and K, L2 and L3 shell/subshell fluorescence yields of some elements in the atomic number range 30 ≤ Z ≤ 40

K shell radiative transition probabilities and K, L₂ and L₃ shell/subshell fluorescence yields were measured using the K_β/K_α intensity ratio for seven elements in the atomic number range 30≤Z≤40 (Zn, As, Se, Rb, Sr, Y and Zr). The targets were irradiated with γ photons of energy 59.5 keV from Am-241. The obtained values were compared with the theoretical values. It was observed that the present values agree with previous theoretical results. The L₂ and L₃ subshell fluorescence yields were the first measured for the present elements.     

Chemical effects on L shell fluorescence yields of Ba, La and Ce compounds

Chemical effects on the average L shell fluorescence yields (v_L) for Ba, La and Ce compounds were investigated. Samples were excited by gamma-rays with 59.5 keV energy photons from a ²⁴¹Am radioisotope source. L X-rays emitted by samples were counted by a Si(Li) detector with a resolution 155 eV at 5.9 keV. Chemical effects on the average L shell fluorescence yield (v _L) for Ba, La and Ce compounds were observed. The values are compared with theoretical and experimental ones for the pure elements.     

Laser induced fluorescence in NO2: absolute fluorescence cross sections and quantum yields

Spectrally resolved collision-free absolute fluorescence cross sections have been measured, for NO₂ excited, by the second harmonic of the Nd: YAG laser. The total cross section into the 523.0–650.0 nm range was found to be 2.3 × 10^?20 cm². The measured absorption cross section of 1.46 × 10^?19 cm² implies a quantum yield of 16% over this range.     

Measurement of angular dependencies of M X-ray differential cross sections and production cross sections using 5.96 keV photons

The differential cross sections of the emission of M-shell fluorescence X-rays from Tl and Pb have been measured by 5.96 keV photons at seven angles ranging from 50° to 110°. The differential cross section is found to decrease with the increasing emission angle, showing an anisotropic spatial distribution of M-shell fluorescence X-rays. Furthermore, M-shell fluorescence cross sections and the average fluorescence yields were measured for Pt, Au, Hg, Tl, Pb, Bi, Th, and U at an excitation energy of 5.96 keV using a Si(Li) detector. The experimental results of the total M X-ray fluorescence cross sections and M-shell fluorescence yields were compared with the theoretical values.This revised version was published online in November 2005 with corrections to the Cover Date.     

Measurement of L subshell photoionisation cross sections of Th and U at 22.6, 25.8, 29.2 and 32.9 kev

Bremsstrahlung from an X-ray tube was used to excite secondary targets of Ag, Sn, I and Ba to get nearly monochromatic excitation energies of 22.6, 25.8, 29.2 and 32.9 keV, respectively. Th and U were used as targets. The L X-ray fluorescence cross sections of different lines from the targets have been measured. Of the several methods to obtain L subshell photoionisation cross sections from these fluorescence data, the merits and demerits of four common methods have been explained and the method with least uncertainty was suggested as the best one for such analysis. Following this method, with intensities of the resolved L_γ lines, three L subshell photoionisation cross sections have been obtained using six different sets of atomic parameters. The variation of these cross sections with different atomic parameters has been discussed. For σ₁, all the derived values are within 30% of one other while for σ₂ and σ₃, they are within 12%. Measured cross sections have been compared with the data of others and with the theoretical values of Scofield. Finally, the intensity ratios of different L lines have also been compared with available data and the theoretical values. Within experimental errors, our data are in good agreement with the data of others and with the theoretical predictions.     

Measurements of radiative vacancy transfer probabilities from L3 subshells to M,N and O shells and subshells in the atomic range 72⩽Z⩽92

The probabilities of vacancy transfer, η_L3M, ηL₃M₁, ηL₃M₄, ηL₃M₅, η_L3N, ηL₃N₁, ηL₃N₄, ηL₃N₅, ηL₃O₁ and ηL₃O_4,5 from L₃ subshell to M, N and O shells and subshells for the elements Hf, Ta, W, Re, Pt, Au, HgO, Tl, Pb, Bi, Th, U have been measured using L shell fluorescence yields and X-ray intensity ratios. These experimental values were obtained from samples excited by 59.5-keV γ-rays, which were emitted from an ²⁴¹Am radioisotope source. Also K and L X-rays emitted from samples were measured by means of Si(Li) detector with a resolution of 155 at 5.9 keV. The results obtained from this study are compared with the results of other studies.     

Measurement of L&agr; and Lß X-ray fluorescence cross sections in Er, Ta, W and Au by 16.896–59.543 keV photons

La and Lb X-ray fluorescence cross sections in Er, Ta, W and Au at excitation energies of 16.896, 22.581, 25.770, 32.890, 38.184, 43.949, 50.214 and 59.5 keV were investigated. Measurements were made using a low energy Si(Li) detector coupled to a model 4096 computerized multi-channel analyser. The experimental results were compared with the theoretically calculated values of L X-rays fluorescence cross sections and other experimental results. Good agreement was observed between experimental and theoretical values.     

Photon-induced M-shell X-ray production cross-sections and fluorescence yields in heavy elements at 5.96 keV

Total M-shell X-ray production cross-sections (MXRP) for selected heavy elements between Yb and U at have been measured at 5.96 keV incident photon energy using a Si(Li) detector. The average M-shell fluorescence yields have been derived, using the experimental total M X-ray production cross-sections and theoretical M-shell photoionization cross-sections. Extracted cross-sections and fluorescence yields have been compared with the literature experimental values, theoretical predictions and semiempirical fits.     

The investigations on K and L X-ray fluorescence parameters of gold compounds

The study aimed to determine the chemical effects on the K and L X-ray intensity ratios and the K and L X-ray production cross sections for gold compounds. The K shell fluorescence yields and L shell average yields were also investigated. The samples were excited by 59.5 keV γ-rays from an ²⁴¹Am annular radioactive source and 123.6 keV γ-rays from a ⁵⁷Co annular radioactive source. K and L X-rays emitted from samples were counted by an Ultra-LEGe detector with a resolution of 0.150 keV at 5.9 keV. The experimental values were compared with theoretical, the semi-empirical and other experimental values.