Coster-Kronig Transition Probabilities Research Articles

MEASUREMENT OF L-SUBSHELL X-RAY FLUORESCENCE CROSS SECTIONS AND L-SUBSHELL FLUORESCENCE YIELDS FOR THE ELEMENTS IN THE ATOMIC RANGE 73≤Z≤92 AT 60 KeV

Li (i=1,2, and 3) X-ray fluorescence cross sections have been measured for seven elements in the atomic range 55≤Z≤ 62 at 15.73 keV. The values of Li subshell fluorescence yields (ω1,ω2, and ω3) have been measured for the same elements using the presently measured cross section values and the theoretical Li subshell photoionization cross sections, Coster-Kronig transition probabilities, and emission rates. The measured X-ray fluorescence (XRF) cross section values are in general agreement with the theoretical values evaluated using L subshell fluorescence yields, Coster-Kronig transition probabilities, emission rates, and subshell photoionization cross sections. Furthermore, the L subshell fluorescence yield values are good agreement with the theoretical values.

Method to evaluate empirical photoionisation cross-sections for L3 magnetic sub-states

A method to evaluate empirical values of L3 magnetic sub-state photoionisation cross-sections has been reported. Preliminarily, the method requires scanning of the existing experimental data on L X-ray fluorescence (XRF) cross-sections for energy dependence of Lα/ Lℓ cross-section ratio. After assuring the energy dependence of Lα/ Lℓ cross-section ratio, the ratio is used for the determination of the alignment parameter A2. Thus, the determined A2 value, along with the available data on the sub-shell photoionisation cross-sections σ Li and the Coster–Kronig transition probabilities f ij , is used to evaluate magnetic sub-state photoionisation cross-sections σ Li ( m) for m= 3 2 and 1 2 . The method has been used to evaluate L3 magnetic sub-state photoionisation cross-sections for four elements with Z⩾82, from the measured L XRF cross-sections. To the best of our knowledge, until this date neither theoretical nor semi-empirical data on magnetic sub-state photoionisation cross-sections for these elements has been available, for comparison with such cross-section values and to establish the superiority of one data set over the others.

Measurement of Kα to Lα and Kβ to Lβ intensity ratios of seven elements in the atomic number range 56≤ Z≤66 using photoionization at 59.54 keV

Kα to Lα and Kβ to Lβ intensity ratios for elements Ba, La, Ce, Nd, Sm, Tb, and Dy have been measured at the excitation energy of 59.54 keV γ-rays from 241Am radioactive source of strength 100 mCi. Intensity ratios were determined by measuring K and L X-rays emitted from standard target of a given element. Theoretical values of the Kα to Lα and Kβ to Lβ intensity ratios were calculated using theoretically tabulated values of shell/subshell photoionization cross-sections, fluorescence yields, Coster–Kronig transition probabilities and radiative decay rates for η KL i ≠0 and η KL i =0. Experimental results were compared with the theoretical values.

Measurement of Lα/ Lℓ, Lα/ Lβ and Lα/ Lγ X-ray intensity ratios for elements in the atomic range 57⩽ Z⩽92 using radioisotope X-ray fluorescence

Lα/ Lℓ, Lα/ Lβ and Lα/ Lγ intensity ratios have been measured for some elements with atomic range 57⩽ Z⩽92 by using characteristic L X-rays from targets excited by 59.54 keV photons from a filtered radioisotope 241Am point source. Theoretical values of the Lα/ Lℓ, Lα/ Lβ and Lα/ Lγ intensity ratios were calculated using theoretically tabulated values of subshell photoionization cross-sections, fluorescence yields, fractional X-ray emission rates, Coster–Kronig transition probabilities. Experimental results have been compared with the theoretical values and other available experimental results. Good agreement was observed between experimental results, other available experimental results and theoretically calculated values.

AUGER RATES FOR Ni-, Cu-, AND Zn-LIKE IONS

Relativistic calculations of nonradiative transition rates to K-, L-, and M-shell vacancy states in Ni-, Cu-, and Zn-like ions with Z=32, 36, 42, 47, 56, 60, 66, 74, 83, and 92 are performed. Auger and Coster–Kronig transition probabilities are calculated using both Dirac–Hartree–Fock and model-potential wave functions. Tabulated data are presented for K- and L-shell Auger rates in Ni-, Cu-, and Zn-like ions, for M-shell Auger rates in Zn-like ions, and for L- and M-shell Coster–Kronig rates in Cu-like ions. Results obtained by averaging over angular momentum substates are also presented and semiempirical formulas are given for the average rates.

L x-ray production cross sections in Th and U at 17.8,25.8 and 46.9 keV photon energies

The L x-ray production (XRP) differential cross sections in Thand U have been measured at the 17.8 keV incident photon energy(E_L3<Einc<E_L2, ELi is the Lisubshell ionization threshold) in an angular range90°-160°, and at the 25.8 and 46.9 keV incident photonenergies (E_L1<Einc<EK) at an angle of130°. The measurements were performed using the energydispersive x-ray fluorescence set-up in secondary excitationmode. In contrast to the findings of an earlier experiment (Sharmaand Allawadhi 1999 J. Phys. B: At. Mol. Opt. Phys. 32 2343), the present measurementsrule out the possibility of a strong angular dependence ofdifferential cross sections for various L3 subshell x-raysfollowing selective photoionization of the L3 subshell.Integral L XRP cross sections at the 17.8, 25.8 and 46.9 keVphoton energies, deduced assuming isotropic emission of the Lx-rays, are found to be in good agreement with those evaluatedusing the most reliable theoretical values of Li(i = 1,2,3) subshell photoionization cross sections,fluorescence yields, x-ray emission rates and Coster-Kronigtransition probabilities.

Measurements of L l, L α, L η, L β and L γ X-ray fluorescence cross-sections in 70⩽ Z⩽92 elements excited by 59.543 keV photons

L l , L α , L η , L β and L γ X-ray fluorescence cross-sections have been measured for the elements Yb, Lu, W, Hg, Tl, Pb, Bi and U using excitation energy of 59.543 keV. Measurements have been performed using an 241Am annular source and a Si(Li) detector. The experimental values of the cross-sections were determined by measuring the absolute yield of L subshell X-rays emitted from a standard target of a given element irradiated with photons of given energy. The theoretical values of the cross-sections were calculated using theoretically tabulated values of subshell photoionization cross-sections, fluorescence yields, Coster–Kronig transition probabilities and radiative decay rates. Experimental results have been compared with the theoretically calculated values of L X-ray cross-sections. A fairly good agreement is obtained between the experimental and the calculated values.

Experimental determination of L-subshell fluorescence yields for heavy elements at 59.54 keV

L-shell X-ray production cross-sections have been measured for selected heavy elements with 70 ≤ Z ≤ 92 at 59.54 keV using a Si(Li) detector. The L-subshell X-ray fluorescence yields ω1, ω2 and ω3 have been derived using the experimental L X-ray production cross-sections, theoretical L-subshell photoionization cross-sections, Coster–Kronig transition probabilities and fractional X-ray emission rates. The data obtained are compared with the literature experimental data, theoretical predictions based on Dirac–Hartree–Slater wave functions and semi-empirical compilations.

L-subshell ionization of Bi, Au, and Yb induced by F ions at intermediate velocities

We have measured the absolute cross sections for the L-subshell ionization for Yb, Au, and Bi induced by intermediate and low-energy F ions. A comparative study of the different methods of extracting the vacancy production cross sections from the L x-ray line intensities is presented. The measured cross sections are compared with the available theoretical calculations based on the perturbed stationary state (PSS) approximation including the effects due to the increased binding energy, Coulomb (C) deflection, energy (E) loss, and the relativistic (R) wave function (ECPSSR). In the case of Yb and Au targets, the ratio of the subshell ionization cross section for ${L}_{1}$ to that for ${L}_{2}$ is found to be larger than 1.0 contrary to theoretical predictions, whereas the ratio is less than 1.0 for Bi, as expected. Similar ratios for the ${L}_{2}$ to ${L}_{3}$ subshells are, however, in agreement with the theoretical predictions for all three targets. These observations can be understood in terms of the multiple vacancies in the outer shells and their effect on the fluorescence yields and Coster-Kronig transitions. In the case of ${L}_{1}$ ionization, the ECPSSR calculations are found to fall much below the experimental data for Yb and Au, and a part of the deviation is understood to be due to the existence of multiple vacancies in the outer shells and the interplay between the Coster-Kronig and radiative transition probability. Quantitative estimates on the enhancement in the effective fluorescence yields of the ${L}_{1}$ subshell are also provided for all three targets.

L[formula omitted], Lα, Lβ and Lγ X-ray production cross-sections and yields of some selected elements between caesium and erbium following ionization by 59.54 keV γ rays

L l , Lα, Lβ and Lγ X-ray production cross-sections were measured in elements from Cs to Er following ionization for 59.54 keV γ-rays from an 241Am point source. The measured values are compared with theoretical predictions estimated using subshell photoionization cross-sections, fluorescence yields, Coster–Kronig transition probabilities, K to L i subshell vacancy transfer probabilities and radiative decay rates. Average L-shell fluorescence yields were deduced from present measured total L X-ray production cross-sections, theoretical K and L photoionization cross-sections and K to L vacancy transfer probabilities. The obtained results for L X-ray production cross-sections and average L-shell fluorescence yields are compared with recent experimental values, theoretical predictions, and semiempirical fits.

L-subshell fluorescence cross sections and L-subshell fluorescence yields in elements 68 ⩽ Z ⩽ 92 by 59.5 keV photons

L-subshell (σ1,σ2 and σ3) x-ray fluorescence cross sections were measured for Er, Ta, W, Au, Hg, Tl, Pb, Bi, Th and U at an excitation energy of 59.5 keV using a Si(Li) detector coupled to a model 4096 computerized multi-channel analyser. The values of Li-subshell fluorescence yields (ω1, ω2 and ω3) have been measured for the same elements using the previously measured cross section values and the theoretical Li-subshell photoionization cross section Coster-Kronig transition probabilities and emission rates. It is observed that the measured Li (i = 1, 2 and 3) subshell x-ray fluorescence cross section and Li-subshell fluorescence yield (ω1, ω2 and ω3) values for the elements are in general agreement with the theoretical ones evaluated using L-subshell fluorescence yields and the L-subshell photoionization cross section.

Photon-induced L X-ray production differential cross sections in thorium at 22.6 keV

The Ll, Lα, Lβ 2,4, Lβ 1,3 and Lγ 1,5 X-ray production differential cross sections in 90Th have been measured at 22.6 keV incident photon energy in an angular range 50–130°. The measurements were performed using a 109Cd annular-source and a Si(Li) detector. The measured differential cross sections for various L X-rays are found to be angle-independent within experimental error. This is contrary to the strong angular-dependence of photon-induced Ll and Lα X-ray production cross sections as reported by Kahlon et al. (K.S. Kahlon, H.S. Aulakh, N. Singh, R. Mittal, K.L. Allawadhi, B.S. Sood, Phys. Rev. A 43 (1991) 1455) and Ertugrul (M. Ertugrul, Nucl. Instr. and Meth. B 119 (1996) 345). Integral cross sections for production of Ll, Lα, Lη, Lβ 6, Lβ 2,4, Lβ 1,3, Lβ 9,10, Lγ 1,5 and total Lγ X-rays are also deduced and are found to be in good agreement with those calculated using reliable theoretical values of the L i ( i=1, 2, 3) subshell photoionisation cross sections, fluorescence yields, X-ray emission rates and Coster–Kronig transition probabilities.

L X-ray fluorescence cross-sections of heavy elements excited by 16.04, 16.90 and 17.78 keV photons

Abstract L l , L α , L β , L γ X-ray fluorescence cross sections have been measured for the elements Au, Pt, W, Lu, Yb, Tm, Ho, Dy and Tb using photon energies of 16.04, 16.90 and 17.78 keV. Measurements have been performed using an X-ray tube with a secondary-exciter system as an excitation source. The secondary exciters used are Zr, Nb and Mo of pure metal sheets (99.99%). A Mo X-ray tube with a secondary-target arrangement was used to obtain high intensity with a high degree of monochromaticity. Using an X-ray tube made it possible to measure X-ray fluorescence cross-sections and intensity ratios even for low intensity X-ray lines. The experimental values of the cross-sections were determined by measuring the absolute yield of L subshell X-rays emitted from a standard target of a given element irradiated with photons of given energy. The theoretical values of the cross-sections were calculated using theoretically tabulated values of subshell photoionization cross-sections, fluorescence yields, Coster–Kronig transition probabilities and radiative decay rates. Experimental results have been compared with the theoretically calculated values of L X-ray cross-sections. A fairly good agreement is observed between the experimental and the calculated values. The intensity ratios I Lβ / I Lα and I Lγ / I Lα were measured and found to be in good agreement with the calculated values.

Measurement of L subshell X-ray fluorescence cross sections and L subshell fluorescence yields for elements in the atomic range 73≤Z≤92 at 60 keV

L i (i=1, 2 and 3) X-ray fluorescence cross sections have been measured for ten elements in the atomic range 73≤Z≤92 at 60 keV. The values of L i subshell fluorescence yields (ω1, ω2 and ω3) have been measured for the same elements using the presently measured cross section values and the theoretical L i subhell photoionisation cross sections, Coster-Kronig transition probabilities and emission rates. The measured X-ray fluorescence (XRF) cross section values are in general agreement with the theoretical values evaluated using L subshell fluorescence yields, Coster-Kronig transition probabilities, emission rates and subshell photoionisation cross sections. Furthermore, the values of L subshell fluorescence yields are in good agreement with the theoretical values.

L X-ray intensity ratios in heavy elements at 59.5 and 122 keV photons

The L shell X-ray intensity ratios ILα/ILβ, ILα/IL1 and ILα/ILγ for Ta, W, Re, Au, Hg, Tl, Pb, Bi, Th and U have been measured at excitation energies of 59.5 and 122 keV with a Si(Li) detector. Measurements have been performed using Am-241 and Co-57 radioisotope sources. A comparison is made of the experimental results with calculated values obtained using theoretical X-ray emission rates, subshell ionization cross-sections, subshell fluorescence yields and Coster-Kronig transition probabilities. A fairly good agreement is observed between experimental and theoretical values.

Measurement of LI, Lα, Lβ and Lγ x-ray fluorescence cross-sections in heavy elements excited by 59.5 and 123.6 keV photons

L1, Lα, Lβ and Lγ XRF cross-sections were measured in heavy elements 73 ⩽ Z ⩽ 92 at excitation energies of 59.5 and 123.6 keV photons. Measurements were made using two excitation sources. The experimental values of the cross-sections were determined by measuring the absolute yield of L-subshell x-rays emitted from a target of a given element and thickness when it was bombarded with a known flux of photons of given energy. It is observed that the measured L XRF cross-section values for the elements are in general agreement with the theoretical ones evaluated using L-subshell fluorescent yields (ωi) and Coster-Kronig transition probabilities (fij) based on the relativistic Dirac-Hartree-Slater theory. The present and previous measured and calculated values of the cross-sections are tabulated to bring out the existing status of L x-rays production cross-sections.

Measurement of cross-sections and Coster-Kronig transition effect on L subshell X-rays of some heavy elements in the atomic range 79≤ Z≤92 at 59.5 keV

L l , L α, L β and L γ X-ray production cross sections have been measured in the atomic range 79≤ Z≤92 at 59.5 keV by measuring differential cross-sections. The experimental values of the cross-sections were determined by measuring the absolute yield of L subshell X-rays emitted from a target of a given element and thickness when it was bombarded with a known flux of photons of given energy. The theoretical values of the cross-sections were calculated from the theoretical values of subshell photoionization cross-sections, fluorescence yields, Coster-Kronig transition probabilities and radiative decay rates. The enhancement effect of Coster-Kronig transition have been calculated of these elements at same energy. Coster-Kronig processes are radionless transitions in which an inner-shell vacancy is transferred from one subshell of an atom to another that is less tightly bound, both belonging to the same principal shell. Experimental measurements were carried out on a few elemental samples to examine the effect to Coster-Kronig transitions on fluorescence cross-sections for the L subshell X-ray lines using 59.5 keV for excitation. Absolute values of the L subshell X-ray cross-sections were also calculated with incorporation of the enhancement due to the Coster-Kronig effect for the elements in the range 79≤ Z≤92 at the same excitation energy. The present results are compared with the other experimental and theoretical values.

Measurement of M X-ray production cross sections in gold by proton, oxygen and nickel ion impact

Measurements of M-shell X-ray production cross sections in Au with proton, O 5+- and Ni 5+-ion impact have been performed. The energy of the incident protons range from 1 to 5 MeV, oxygen ions from 66 to 72 MeV and nickel ions from 58 to 87 MeV. The experimental results have been compared with the predictions of the plane wave Born approximation (PWBA) and the perturbed stationary state theory with energy loss, Coulomb deflection and relativistic corrections (ECPSSR). For proton impact the measured cross sections have been found to be in good agreement with both these theories. With O-ion impact the ECPSSR theory underpredicts the experimental data while the PWBA agrees fairly well. Both the theories, however, strongly underestimate the X-ray cross sections measured with Ni-ion impact. The discrepancy between the experimentally measured and theoretically calculated cross sections in case of heavy ion impact could be due to multiple ionization which changes the values of atomic parameters like sub-shell fluorescence yields, Coster-Kronig transition probabilities and emission rates.

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 Li subshell fluorescence yields ωi, Coster-Kronig transition probabilities ƒij based on the Relativistic-Hartree-Slater theory, K to Li subshell vacancy transfer probabilities nKLi, fractions of the ratiative width of the subshell Fny and Li subshell photoionisation cross section σPi. The average L shell fluorescence yields ωL 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.

The vacancy transfer probability dependence on relative L X-ray intensities in the atomic range 57 ≤ Z ≤ 92 at 59.5 keV

The Lα Lβ , Lα Lγ , Ll Lβ , Ll Lγ and Lβ Lγ intensity ratios were measured by measuring the characteristic X-ray intensities in 24 elements over the range 57 ≤ Z ≤ 92 using a 100 mCi 241Am filtered source for excitation. A comparison is made of the experimental results with the calculated values obtained by using theoretical X-ray emission rates, subshell photoionisation cross sections, subshell fluorescence yields and Coster-Kronig transition probabilities. A fairly good agreement is observed between experimental and theoretical values. The experimental and theoretical values of these ratios versus Z were fitted. The enhancement effect of K to Li subshell vacancy transfer on relative L X-ray intensities are shown in these curves.