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/.     

Electron impact collision strengths in Sn XXIII

The energy levels, multipole (E1, M1, E2, and M2) transition rates, and electron-impact collision strengths are calculated for Sn XXIII. The data refer to 107 fine-structure levels belonging to the configurations (1s²2s²2p⁶)3s²3p⁶3d¹⁰, 3s²3p⁶3d⁹4?, 3s²3p⁵3d¹⁰4?, and 3s3p⁶3d¹⁰4?(? = s, p, d, and f). The collision strengths are calculated with a 20-collision-energy grid in terms of the energy of the scattered electron between 37.5 and 8436 eV by using the distorted-wave approximation. Effective collision strengths are obtained at five electron temperatures, T_e (eV) = 193.89, 387.78, 581.67, 775.57, and 969.46, by integrating the collision strengths over a Maxwellian electron distribution.     

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.     

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 excitations for La XXX

The energy levels, spontaneous radiative decay rates, and electron impact collision strengths are calculated for La XXX. 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 20-collision-energy grid in terms of the energy of the scattered electron between 10 and 10,000 eV by using the distorted-wave approximation. Effective collision strengths are obtained at seven electron temperatures: T_e (eV) = 10, 100, 300, 500, 800, 1000, 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 La X-ray laser at 8.8 nm.     

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.     

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.     

Atomic data for dielectronic satellite lines and dielectronic recombination into Ne

Energy levels, radiative transition probabilities, and autoionization rates for B-like neon (Ne⁵⁺) including 1s²2s²nl, 1s²2s2pnl, and 1s²2p²nl (n = 2-11 and l = 0-7) states were calculated using a multiconfigurational Hartree-Fock method (Cowan code) and a relativistic many-body perturbation theory method (RMPT) code. Autoionizing levels above three thresholds (1s²2s²¹S, 1s²2s2p ³P, 1s²2s2p ¹P) were considered. We find that configuration mixing (2s²nl + 2p²nl) plays an important role for all atomic characteristics. Branching ratios relative to the first threshold and the intensity factor were calculated for satellite lines and dielectronic recombination rate coefficients for the 190 odd-parity and 198 even-parity excited states. The dielectronic recombination rate coefficients including 1s²2s²nl, 1s²2s2pnl, and 1s²2p²nl (n = 2-11 and l = 0-7) states were calculated. The contributions from the excited states higher than n = 11 were estimated by extrapolation of all atomic characteristics to derive the total dielectronic recombination rate coefficient. It is found that the distribution of the rate coefficients as a function of the orbital angular momentum quantum number shows a peak at l = 5. The total dielectronic recombination rate coefficient was derived as a function of electron temperature. The dielectronic satellite lines were also obtained. The state selective dielectronic recombination rate coefficients to excited states of B-like neon were obtained, which are useful for modeling Ne VI spectral lines in a recombining plasma.     

Weighted oscillator strengths for the Xe IV spectrum

The weighted oscillator strengths, gf, of 769 previously reported classified spectral lines, and 49 new observed and also classified lines belonging to the 5s²5p³, 5s5p⁴, 5s²5p²(6p + 4f), and 5s²5p²(5d + 6s) transitions array in Xe IV, were determined through a multiconfigurational Hartree-Fock relativistic approach. In this calculation, the electrostatic parameters were optimized by a least-square procedure in order to improve the adjustment to experimental energy levels.     

Energies, wavelengths, and transition probabilities for Ge-like Kr, Mo, Sn, and Xe ions

Energy levels, wavelengths, transition probabilities, and oscillator strengths have been calculated for Ge-like Kr, Mo, Sn, and Xe ions among the fine-structure levels of terms belonging to the ([Ar] 3d¹⁰)4s²4p², ([Ar] 3d¹⁰)4s 4p³, ([Ar] 3d¹⁰)4s²4p 4d, and ([Ar] 3d¹⁰)4p⁴ configurations. The fully relativistic multiconfiguration Dirac-Fock method, taking both correlations within the n=4 complex and the quantum electrodynamic effects into account, have been used in the calculations. The results are compared with the available experimental and other theoretical results.     

New atomic data for Ti X

A large-scale configuration interaction (CI) calculation using CIV3 is performed for the 303 fine-structure levels of the aluminum-like titanium ion. We have calculated the energy levels, oscillator strengths, and transition probabilities for the electric dipole allowed and intercombination transitions among the levels of ground state 3s²3p (²p^o) and higher energy levels of states 3s3p², 3p³, 3s3p3d, 3p²3d, 3s²4s, 3s3d², 3s²4p, 3s3p4s, 3s3p4p, 3p3d², 3s3p4d, 3s3p4f, 3s²5p, 3p²4p, 3s3d4s, 3s3p5s, 3s3d4p, 3s3p5p, 3s²(4d, 4f, 5s, 5d, 5f, 6s, 6p, 6d, 6f) of Ti X in the LSJ coupling scheme. The calculations include all the major correlation effects. We attempt to correct the inaccuracies in the CI coefficients in the wavefunctions, which would lead to inaccuracies in transition probabilities by applying a “fine-tuning” technique. The relativistic effects are incorporated by adding the mass correction, Darwin, and spin-orbit interaction terms into the non-relativistic Hamiltonian in the Breit-Pauli approximation. The present results are in good agreement with other available calculations and experiments. Several new lines corresponding to 3s3pnl (n = 4, 5 and l = 0, 1), 3s²5p, 3s²(6s, 6p) and other configurations are predicted where no other theoretical or experimental results are available. We expect that our extensive calculations will be useful to experimentalists in identifying the fine-structure levels in their future work.     

Collision strengths and line strengths for all transitions among the levels of the 1s22s22p, 1s22s2p2, and 1s22p3 configurations of boron-like ions

Collision strengths and electric-dipole line strengths have been calculated for all fine-structure transitions among the levels of the 1s²2s²2p, 1s²2s2p², and 1s²2p³ configurations in 17 boron-like ions with nuclear charge number Z in the range 10 ⩽ Z ⩽ 74. From these results the collision strengths and line strengths for transitions between energy terms and their analogs in jj coupling can also be obtained. The collision strength data cover impact-electron energies ⩽ 3.25Z²Ry or 44.2Z²eV. The effects of configuration mixing, parentage mixing, and intermediate coupling have been included in the calculations. The method used in calculating the collision strengths is a Coulomb-Born-Exchange method well suited for treating many members of an isoelectronic sequence simultaneously. The complete results have been given in terms of fits to simple functions of the impact-electron energy that are readily integrated over a Maxwellian distribution to obtain collision rates. Some discussion is given of important differences between the present method and the more usual Coulomb-Born-Exchange method, where it is assumed that the free electron sees the screened nuclear charge (Z - N).     

Fine-structure calculations of energy levels, oscillator strengths, and transition probabilities for sodium-like ions (Co XVII-Kr XXVI)

We have calculated fine-structure energy levels, oscillator strengths and transition probabilities for transitions among the terms belonging to the 1s²2s²2p⁶ns (²S), 1s²2s²2p⁶np (²P), 1s²2s²2p⁶nd (²D) (n = 3, 4, 5), and 1s²2s²2p⁶nf (²F) (n = 4, 5) configurations. The calculations are based upon the general configuration-interaction code CIV3 of Hibbert which uses orthonormal orbitals of radial functions expressed as superpositions of normalized Slater-type orbitals. Our calculated values are compared with experimental and other theoretical results where a satisfactory agreement is found. We also report on some unpublished energy values and oscillator strengths.     

Atomic data and spectral line intensities for Mg VI

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Mg VI. The configurations used are 2s²2p³, 2s2p⁴, 2p⁵, 2s²2p²3s, 2s²2p²3p, and 2s²2p²3d, giving rise to 72 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies, 12, 24, 36, 48, and 60 Ry. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10⁸-10¹⁴ cm⁻³ at an electron temperature of log T_e (K) = 5.6, corresponding to maximum abundance of Mg VI. Relative and absolute spectral line intensities are calculated and compared with observations of a solar active region.     

Electron-impact excitation of Fe II: Effective collision strengths for optically allowed fine-structure transitions

In this paper, we present collision strengths and Maxwellian averaged effective collision strengths for the electron-impact excitation of Fe II. We consider specifically the optically allowed lines for transitions from the 3d⁶4s and 3d⁷ even parity configuration states to the 3d⁶4p odd parity configuration levels. The parallel suite of Breit-Pauli codes are utilized to compute the collision cross-sections where relativistic effects are included explicitly in both the target and the scattering approximation. A total of 100 LS or 262-jj levels formed from the basis configurations 3d⁶4s, 3d⁷ and 3d⁶4p were included in the wavefunction representation of the target, including all doublet, quartet and sextet terms. The Maxwellian averaged effective collision strengths are computed across a wide range of electron temperatures from 100 to 100,000 K, temperatures of importance in astrophysical and plasma applications. A detailed comparison is made with previous works and significant differences were found to occur for some of the transitions considered. We conclude that in order to obtain converged collision strengths and effective collision strengths for these allowed transitions it is necessary to include contributions from partial waves up to L = 50 explicitly in the calculation, and in addition, account for contributions from even higher partial waves through a “top up” procedure.     

Atomic data and spectral line intensities for Mg V

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Mg V. The configurations used are 2s²2p⁴, 2s2p⁵, 2p⁶, 2s²2p³3s, 2s²2p³3p, and 2s²2p³3d, giving rise to 86 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies, 10, 20, 30, 40, and 50 Ry, in the distorted wave approximation. Excitation rate coefficients (not tabulated here) are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. To calculate excitation rate coefficients, collision strengths at low and high energy limits are calculated by a method described by Burgess and Tully. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10⁸-10¹⁴ cm⁻³ at an electron temperature of log T_e = 5.4, corresponding to the maximum abundance of Mg V. Fractional level populations and relative spectral line intensities are also calculated. Our calculated intensities are compared with the active region observations from the solar EUV rocket telescope and spectrograph (SERTS) and the diagnostic properties of Mg V are discussed. This dataset will be made available in the next version of the CHIANTI database.     

Atomic data and spectral line intensities for Ar XI

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ar XI. The configurations used are 2s²2p⁴, 2s2p⁵, 2p⁶, 2s²2p³3s, 2s²2p³3p, and 2s²2p³3d giving rise to 86 fine-structure levels in intermediate coupling. Collision strengths are calculated at five incident energies (30, 60, 90, 120, and 150 Ry) in the distorted wave approximation. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10⁸-10¹⁴ cm⁻³ at an electron temperature of log T_e (K) = 6.3, corresponding to the maximum abundance of Ar XI. Relative and absolute spectral line intensities are calculated, and their diagnostic relevance is discussed. This dataset will be made available in the next version of the CHIANTI database.     

Electron-impact-excitation collision strengths for Be-like ions: II. Intermediate-energy region and collision rates

Intermediate-energy collision strengths calculated using the R-matrix method are presented for four Be-sequence ions, C III (2.6–8.0 Ry), O V (4.4–12.0 Ry), Ne VII (8.4–20.0 Ry), and Si XI (11.0–34.0 Ry). The six ionic states (2s²) ¹S, (2s2p)³P⁰, ¹P⁰ and (2p²)³P^e, ¹D^e, ¹S^e, corresponding to ten fine-structure levels, are included, leading to 29 independent transitions per ion. High-energy analytical expressions have also been calculated for the collision strengths. These results have been combined with previously published low-energy collision strengths to deduce effective collision strengths (that is, collision rates) for ranges of electron temperature appropriate to the four ions.     

Atomic data and spectral line intensities for Ni XIV

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ni XIV. We include in the calculations all the configurations belonging to the n=3 complex, and provide data for the lowest 143 fine-structure levels, belonging to the configurations 3s²3p³, 3s3p⁴, 3s²3p²3d, 3p⁵, 3s3p³3d, and 3s²3p3d². Collision strengths are calculated at six incident energies for all transitions: 0.112, 8.07, 21.3, 43.4, 80.3, and 141.8 Ry above the threshold of each transition. Calculations have been carried out using the Flexible Atomic Code. Excitation rate coefficients are calculated as a function of electron temperature by assuming a Maxwellian electron velocity distribution. Using the excitation rate coefficients and the radiative transition rates of the present work, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10⁸-10¹⁴ cm⁻³ and at an electron temperature of , corresponding to the maximum abundance of Ni XIV. Spectral line intensities are calculated, and their diagnostic relevance is discussed. This data set is available in version 6.0 of the CHIANTI database.