Theoretical transition probabilities, oscillator strengths, and radiative lifetimes of levels in Pb IV

Transition probabilities and oscillator strengths of 176 spectral lines with astrophysical interest arising from 5d¹⁰ns (n = 7,8), 5d¹⁰np (n = 6,7), 5d¹⁰nd (n = 6,7), 5d¹⁰5f, 5d¹⁰5g, 5d¹⁰nh (n =  6,7,8), 5d⁹6s², and 5d⁹6s6p configurations, and radiative lifetimes for 43 levels of Pb IV, have been calculated. These values were obtained in intermediate coupling (IC) and using relativistic Hartree-Fock calculations including core-polarization effects. For the IC calculations, we use the standard method of least-square fitting from experimental energy levels by means of the Cowan computer code. The inclusion in these calculations of the 5d¹⁰7p and 5d¹⁰5f configurations has facilitated a complete assignment of the energy levels in the Pb IV. Transition probabilities, oscillator strengths, and radiative lifetimes obtained are generally in good agreement with the experimental data.     

Relativistic oscillator strengths in the boron isoelectronic sequence

Oscillator strengths for electric dipole transitions, between states of the ground complex of the boron isoelectronic sequence up to Z = 93, are studied by means of relativistic wave functions obtained from a central field model. A graphical representation for 45 transitions is presented and the results are analyzed by means of the relativistic Z-dependent theory of Layzer and Bahcall. In the intermediate Z-region anticrossing effects appear which cause some irregularities in the behavior of the oscillator strengths.     

Electron impact collision strengths and transition rates for extreme ultraviolet emission from Xe

The energy levels, oscillator strengths, and electron impact collision strengths are calculated for the Xe¹⁰⁺ ion using the configuration interaction scheme implemented by the Flexible Atomic Code. These data pertain to the 3917 levels belonging to the following configurations: 4s²4p⁶4d⁸, 4s²4p⁶4d⁷4f, 4s²4p⁶4d⁷5l (l = s, p, d, or f), 4s²4p⁵4d⁹, 4s²4p⁵4d⁸4f, 4s²4p⁵4d⁸5l, 4s²4p⁶4d⁶5s5p, 4s²4p⁶4d⁶5p5d. Configuration interactions among these configurations are included in the calculation. Collision strengths are obtained at 10 scattered electron energies (1-1000 eV) and are tabulated here at five representative energies of 10, 50, 100, 500, and 1000 eV. Effective collision strengths are obtained by assuming a Maxwellian electron velocity distribution at 10 temperatures ranging from 10 to 100 eV, and are tabulated at five representative temperatures of 10, 30, 50, 70 and 100 eV in this work. The whole data set should be useful for research involving extreme ultraviolet emission from Xe¹⁰⁺.     

Energy levels, transition probabilities, and electron impact excitation collision strengths for Xe XXVII

The energy levels, spontaneous radiative decay rates, and electron impact collision strengths are calculated for Xe XXVII. The data refer to 107 fine-structure levels belonging to the configurations (1s²2s²2p⁶)3s²3p⁶3d¹⁰, 3s²3p⁶3d⁹4l, 3s²3p⁵3d¹⁰4l and 3s3p⁶3d¹⁰4l (l = s, p, d, f). The collision strengths are calculated with a grid of 20 collision energies between 10 and 1500 eV in terms of the energy of the scattered electron, by using the distorted-wave approximation. Effective collision strengths are obtained at six temperatures, T_e (eV) = 10, 100, 300, 500, 800 and 1500, by integrating the collision strengths over a Maxwellian electron distribution. Coupled with these atomic data, a hydrodynamic code MED103 can be used to simulate the Ni-like Xe X-ray laser.     

Level energies, oscillator strengths, and lifetimes for transitions in Ti VI

We present an extensive, ab initio configuration interaction calculation of oscillator strengths, transition probabilities, and lifetimes of the upper levels of all transitions in Ti VI between the levels of 3s²3p⁵, 3s3p⁶, 3p⁴3d, 3p⁴4s, 3p⁴4p and 3p⁴4d states in the LSJ coupling scheme. Relativistic effects are incorporated by adding the mass correction, Darwin, and spin-orbit interaction terms to the non-relativistic Hamiltonian in the Breit-Pauli approximation. The calculations incorporate the major correlation effects. The calculated energy levels are in close agreement with most of the NIST tabulation. However, some discrepancies in the energy positions with experimental energies occur in levels with 3p⁴3d ¹D and ³P cores, particularly belonging to ²P and ²D symmetries. We predict new data for several levels where no other theoretical and/or experimental results are available. Our extensive calculations will be useful to experimentalists in identifying the fine-structure levels in their future work.     

Energy levels, oscillator strengths and transition probabilities for Si-like P II, S III, Cl IV, Ar V and K VI

Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for transitions among the terms belonging to 3s²3p², 3s3p³, 3s²3p3d, 3s²3p4s, 3s²3p4p, 3s²3p4d, 3s²3p5s and 3s²3p5p configurations of silicon-like ions P II, S III, Cl IV, Ar V and K VI have been calculated using configuration-interaction version 3 (CIV3). We compared our data with the available experimental data and other theoretical calculations. Most of our calculations of energy levels and oscillator strengths (in length form) show good agreement with both experimental and theoretical data. Lifetimes of the excited levels are also given.     

Energy levels,oscillator strengths,radiative decay rates,and fine-structure collision strengths for the Zn-like ions Nb XII and Mo XIII

Energy levels, line strengths, oscillator strengths, radiative decay rates, and fine-structure collision strengths are presented for the Zn-like ions Nb XII and Mo XIII. The atomic data are calculated with the AUTOSTRUCTURE code, where relativistic corrections are introduced according to the Breit–Pauli distorted wave approach. We present the calculations of atomic data for 110 fine-structure levels generated from fifteen configurations (1s²2s²2p⁶3s²3p⁶3d¹⁰)4s², 4s4p, 4p², 4s4d, 4s4f, 4s5s, 4p4d, 4s5p, 4s5d, 4p4f, 4p5s, 4d², 4d4f, 4f², and 3d⁹4s²4p. Fine-structure collision strengths for transitions from the ground and the first four excited levels are presented at six electron energies (20, 50, 80, 110, 150, and 180 Ryd). Our atomic structure data are compared with the available experimental and theoretical results.     

Electron impact collision strengths and oscillator strengths for Ge-, Ga-, Zn-, Cu-, Ni-, and Co-like Au ions

Energy levels, oscillator strengths, and electron impact collision strengths have been calculated for Ge-, Ga-, Zn-, Cu-, Ni-, and Co-like Au ions. For Ni-like Au, these atomic data are obtained among the levels belonging to the configurations of ([Ne])3s²3p⁶3d¹⁰, 3s²3p⁶3d⁹nl, 3s²3p⁵3d¹⁰nl, and 3s 3p⁶3d¹⁰nl (n = 4, 5; l = 0, 1, … , n − 1). For other Au ions, more levels have been obtained with special attention to atomic data up to transitions of 5f → 3d for emission or 3d → 5f for absorption. Configuration interactions are taken into account for all levels included. Collision strengths have been obtained at 20 scattered electron energies (5-40,000 eV) and they are listed at six representative energies of 100, 500, 1000, 5000, 10,000, and 20,000 eV in this work. Effective collision strengths have been obtained by assuming a Maxwellian electron velocity distribution at 10 representative temperatures ranging from 500 to 5000 eV. The present dataset should be adequate for most applications. The energy levels are expected to be accurate to within 0.5%, while oscillator strengths and collision strengths for strong transitions are probably accurate to better than 20%. The complete dataset is available electronically from http://www.astronomy.csdb.cn/EIE/.     

Electron impact collision strengths and oscillator strengths for Ni-like Nd, Sm, Eu, Gd, Ta, and W ions

Energy levels, oscillator strengths, and electron impact collision strengths have been calculated for Ni-like ions of Nd (Z = 60), Sm (Z = 62), Eu (Z = 63), Gd (Z = 64), Ta (Z = 73), and W (Z = 74) among the 249 levels belonging to the ([Ne])3s²3p⁶3d¹⁰, 3s²3p⁶3d⁹nl, 3s²3p⁵3d¹⁰nl, 3s3p⁶3d¹⁰nl (n = 4, 5; l = 0, 1, … , n − 1) configurations. Configuration interactions among these configurations have been included in the calculations. Collision strengths have been obtained at 20 scattered electron energies (5–20,000 eV) and they have been listed at six representative energies of 100, 400, 1000, 2500, 5000, and 10,000 eV in this work. Effective collision strengths have been obtained by assuming a Maxwellian electron velocity distribution at 24 temperatures ranging from 100 to 3000 eV. Our results are compared with those available in the literature. The relative difference is within 0.3% between our calculated energy levels and the corresponding experimental values wherever available. The energy levels are expected to be be accurate within 0.6%, while oscillator strengths and collision strengths for strong transitions are probably accurate to better than 20%. The complete dataset is available electronically from http://www.astronomy.csdb.cn/EIE/.     

K-shell excitation dielectronic recombination resonance strengths of highly charged He-like to O-like Xe ions

Dielectronic recombination is an important process in high temperature plasmas.In the present work,the KLn (n =L,M,N and O) DR resonance strengths of He-like to O-like xenon ions are measured at the Shanghai electron beam ion trap using a fast electron beam energy scanning method.The experiment uncertainty reaches about 6％ with significant improvement of statistics.A relativistic configuration interaction calculation is also made.Theoretical results agree with the experiment results within 15％ in most cases.     

Energies and oscillator strengths for allowed transitions in S V,Cl VI and Fe XV

We present calculations using configuration interaction wave functions of energies and oscillator strengths for allowed transitions between states of the form 3l3l′ or 3l4l′ in S V, Cl VI and Fe XV. For the first two ions, LS coupling has been used throughout, but corrections incorporating experimental energies are made to the wave functions. For Fe XV, mass correction and Darwin terms are added to the Hamiltonian. These substantially improve the agreement between calculated and experimental energies. Some previously undetermined energy levels in Fe XV are predicted.     

Optical oscillator strengths, mean excitation energy, shell corrections and experimental values for stopping power

In a recent paper, Smith, Inokuti, Karstens and Shiles discussed optical oscillator strengths (OOS) of graphite, Al and Si and compared the mean excitation energy I obtained by integration to that from stopping power measurements. They found agreement for graphite and Al, but disagreement for Si. In this paper, we discuss the OOS of Al, Si, Cu and Au and compare the stopping powers calculated from these OOS (or from a single I-value), using program CasP40, directly to experimental stopping power values for protons between 10 and 80 MeV. We find that the choice of proper shell corrections is essential: since the shell correction built into CasP is too small, we take the correction for Al, Si and Cu from the BEST program of Berger and Bichsel. For Au, better results are obtained using Bonderup’s shell correction. With these choices, we find fair agreement between experimental and calculated stopping data, both with the I-values from ICRU Report 49 and with OOS. Even in the case of Si, the stopping curve based on OOS is not in conflict with experimental data. In all cases, the curves calculated using SRIM are in good agreement with the data.     

Excitation energies and oscillator strengths in Al-, Si-, and P-like ions

Theoretical energy levels and transition probabilities are calculated for low-lying levels of aluminum-, silicon-, and phosphorus-like ions from Z = 13 to Z = 106. The multiconfiguration Dirac-Fock technique is used to obtain energy levels and wave functions. Electron correlation effects are accounted for by including many electronic configurations in the self-consistent-field procedure. Contributions from the Breit interaction and the Lamb shift are treated as a first-order perturbation. The electric-dipole, electric-quadrupole, and magnetic-dipole transitions between levels are also calculated.     

Ab initio oscillator strengths and transition probabilities in oxygen-like Cr XVII

Ab initio energy spectra of the ground configuration 2s²2p⁴, the excited configurations 2s2p⁵, 2p⁶, 2s²2p³3s, 2s²2p³3p, 2s²2p³3d, 2s2p⁴3s, 2s2p⁴3p, and 2s2p⁴3d of oxygen-like chromium Cr XVII have been calculated using the configuration interaction method. The wavelengths, oscillator strengths and the emission transition probabilities from configurations 2s²2p³3l and 2s2p⁴3l are obtained. The radiative lifetimes of excited levels are also presented.     

Fine-structure calculations of energy levels,oscillator strengths,and transition probabilities for sulfur-like iron,Fe XI

Energy levels, oscillator strengths, and transition probabilities for transitions among the 14 LS states belonging to configurations of sulfur-like iron, Fe XI, have been calculated. These states are represented by configuration interaction wavefunctions and have configurations 3s²3p⁴, 3s3p⁵, 3s²3p³3d, 3s²3p³4s, 3s²3p³4p, and 3s²3p³4d, which give rise to 123 fine-structure energy levels. Extensive configuration interaction calculations using the CIV3 code have been performed. To assess the importance of relativistic effects, the intermediate coupling scheme by means of the Breit–Pauli Hamiltonian terms, such as the one-body mass correction and Darwin term, and spin–orbit, spin–other-orbit, and spin–spin corrections, are incorporated within the code. These incorporations adjusted the energy levels, therefore the calculated values are close to the available experimental data. Comparisons between the present calculated energy levels as well as oscillator strengths and both experimental and theoretical data have been performed. Our results show good agreement with earlier works, and they might be useful in thermonuclear fusion research and astrophysical applications.     

Transition probabilities and oscillator strengths of E1 transitions in Fe XII and Fe XIV

Non-orthogonal orbitals in the multiconfiguration Hartree-Fock approach are used to calculate line strengths, oscillator strengths and transition probabilities for E1 transitions among the fine-structure levels of the 3s²3p³, 3s3p⁴, 3s²3p²3d, 3s3p³3d, 3p⁵ and 3s²3p3d² configurations in Fe XII and 3s²3p, 3s3p², 3s²3d, 3p³, 3s3p3d, 3p²3d, 3s3d², 3p3d², 3s²4s, 3s²4p, 3s3p4s and 3s²4d configurations in Fe XIV. The lifetimes of excited levels belonging to these configurations of Fe XII and Fe XIV are also presented. An accurate representation of the levels has been obtained using spectroscopic and correlation radial functions. The wavefunctions exhibit large correlations and significant dependence of one-electron valence orbitals due to both the total and intermediate terms. The relativistic corrections are included through the one-body and two-body operators in the Breit-Pauli Hamiltonian. Progressively larger calculations are performed to check for important electron correlation contributions and for convergence of results. The atomic wavefunctions give excitation energies which are in close agreement with experiment. The present oscillator strengths and transition probabilities compare very well with previous large scale calculations.     

Ab initio oscillator strengths and transition probabilities in aluminum-like calcium, Ca VIII

An ab initio study of aluminum-like calcium is presented. The calculations are performed within the configuration interaction method in the basis of transformed radial orbitals with a variable parameter. Relativistic effects are accounted for within the Breit-Pauli approximation. Energy spectra, transition characteristics and lifetimes of excited levels of configurations 3s²3p, 3s3p², 3s²3d, 3p³, 3s3p3d, 3p²3d, 3s²4s, 3s²4p, 3s²4d, 3s²4f, 3s3p4s, and 3s3p4p are obtained. The results are compared with available experimental and theoretical data.     

Calculated oscillator strengths and wavelengths for allowed transitions within the third shell for ions in the Al-like isoelectronic sequence between Cl V and Ni XVI

Theoretical wavelengths and weighted oscillator strengths are tabulated for spectral emission lines of the ions Cl V, Ar VI, Ca VIII, Ti X, Cr XII, Fe XIV, and Ni XVI, together with available measured wavelengths. The computations are made in a theoretical framework which includes all configuration-interactions within the complex of principal quantum number n = 3 and involves the scaling of ab initio values of Slater radial energy integrals based on empirical data. The empirical scale factors and the adopted Slater parameters are listed along with derived energy levels and wave functions. Racah reduced radial dipole matrix elements are also given.     

Calculated oscillator strengths and wavelengths for allowed transitions within the third shell for ions in the Mg-like isoelectronic sequence between S V and Ni XVII

Weighted oscillator strengths, energy levels, and wavelengths are calculated for the 3s²-3s3p, 3s3p-3p², 3s3p-3s3d, 3p²-3p3d, and 3s3d-3p3d transition arrays for Mg-like ions in the sequence from S V to Ni XVII. Their values are tabulated along with Slater radial integrals, Racah reduced radial dipole matrix elements, and level compositions. The theoretical procedure involves the computation of ab initio values for the Slater radial energy integrals and their subsequent optimization in accordance with dependent measured wavelengths. Published energy levels are improved on the basis of new calculations of wavelengths of the 3s²¹S₀-3s3p³P₁ intercombination lines. Observational wavelength and energy-level data are tabulated.