Atomic data and spectral line intensities for Ni XXV

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ni XXV. The configurations used are 2s²,2s2p,2p²,2l3l^′,2l4l^′, and 2s5l^′, with l=s,p and giving rise to 92 fine-structure levels in intermediate coupling. Collision strengths are calculated at seven incident energies (50, 100, 150, 225, 300, 375, and 450 Ry) for the transitions within the three lowest configurations corresponding to the 10 lowest energy levels, and at five incident energies (150, 225, 300, 375, and 450 Ry) for transitions between the lowest five levels and the configurations. The calculations are carried out using 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 of the present work, statistical equilibrium equations for level populations are solved at electron densities covering the range at an electron temperature of , corresponding to the maximum abundance of Ni XXV. 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.     

Atomic data and spectral line intensities for Ar XV

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ar XV. The configurations used are 2s², 2s2p, 2p², 2l3l^′, , with giving rise to 92 fine-structure levels in intermediate coupling. Collision strengths are calculated at eight incident energies (10, 20, 30, 60, 120, 180, 240, and 300 Ry) for transitions within the three lowest configurations, and five incident energies (60, 120, 180, 240, and 300 Ry) for transitions between the lowest five levels and the n = 3, 4, 5 configurations, using 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 of the present work, and R-matrix results for the 2s², 2s2p, 2p² configurations available in the literature, statistical equilibrium equations for level populations are solved at electron densities covering the range of 10⁸-10¹⁴ cm⁻³ at an electron temperature of , corresponding to the maximum abundance of Ar XV. Spectral line intensities are calculated, and their diagnostic relevance is discussed. Observed line ratios indicate electron temperatures of the relevant emitting plasma close to . This dataset will be made available in the next version of the CHIANTI database.     

Atomic data and spectral line intensities for Ca XVII

Electron impact collision strengths, energy levels, oscillator strengths, and spontaneous radiative decay rates are calculated for Ca XVII. The configurations used are 2s², 2s2p, 2p², 2l3l^′, 2l4l^′ and 2s5l^′, with l=s,p, and l^′=s,p,d giving rise to 92 fine-structure levels in intermediate coupling. Collision strengths are calculated at seven incident energies (15, 30, 75, 112.5, 150, 187.5 and 225 Ry) for the transitions within the three lowest configurations corresponding to the 10 lowest energy levels, and at five incident energies (75, 112.5, 150, 187.5 and 225 Ry) for transitions between the lowest five levels and the n=3,4,5 configurations. Calculations have been carried out using 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 of the present work, and R-Matrix results for the 2s², 2s2p, 2p² configurations available in the literature, statistical equilibrium equations for level populations are solved at electron densities covering the range of at an electron temperature of logT_e(K)=6.7, corresponding to the maximum abundance of Ca XVII. 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.     

Oscillator strengths and radiative rates for transitions in neutral sulfur

We present accurate oscillator strengths and radiative rates for 2173 E1 transitions among the 120 levels belonging to 3s²3p⁴, 3s3p⁵, and 3s²3p³(⁴S^o,²D^o,²P^o)n? configurations where . A configuration interaction approach is employed through the standard CIV3 program. The 114 LS states included in the present calculation generate 250 fine-structure levels belonging to the above configurations below 100,000 cm⁻¹. However, results of only 120 fine-structure levels are presented due to the absence of experimental energy values for the remaining levels. Tabulations of oscillator strengths and radiative rates, and their comparison with other calculations, are presented in the first two tables. In a separate table the oscillator strengths and transition probabilities, in length and velocity gauges, are presented for 2173 E1 transitions, and are arranged in ascending order of wavelength.     

Atomic data and spectral line intensities for the boron isoelectronic sequence (Ar XIV through Kr XXXII)

We have calculated the oscillator strengths, radiative decay rates, and the electron collision strenghts for the B-like ions Ar XIV, Ti XVIII, Fe XXII, Ge XXVIII, and Kr XXXII. The corresponding atomic data for the ions Ca XVI, Cr XX, Ni XXIV, Zn XXVI, and Se XXX are determined by interpolation. The configurations included in the calculation are 2s²2p, 2s2p², 2p³, 2s²3s, 2s²3p, and 2s²3d. Using both the computed and the interpolated atomic data, we calculated the populations of the 20 levels belonging to these configurations. The intensities of the transitions are presented for electron densities of interest for the diagnosis of tokamak plasmas (10¹³, 10¹⁴, and 10¹⁵ cm⁻³).     

Atomic data and spectral line intensities for the carbon isoelectronic sequence (Ar XIII through Kr XXXI)

Oscillator strengths, radiative decay rates, and electron collision strengths have been calculated for the C-like ions Ar XIII, Ti XVII, Fe XXI, Zn XXV, Se XXIX, and Kr XXXI. The corresponding atomic data for the ions Ca XV, Cr XIX, Ni XXIII, and Ge XXVII are determined by interpolation. The configurations included in the calculation are 2s²2p², 2s2p³, 2p⁴, 2s²2p3s, 2s²2p3p, and 2s²2p3d. The populations of the 46 levels belonging to these configurations are calculated for electron densities equal to 10¹³, 10¹⁴, and 10¹⁵ cm⁻³, and the spectral line intensities of the transitions from these levels are also presented.     

Atomic data and spectral line intensities for the beryllium isoelectronic sequence (Ar XV through Kr XXXIII)

Oscillator strengths, radiative decay rates, and electron collision strengths are calculated for the ions Ar XV, Ti XIX, Ni XXV, Ge XXIX, and Kr XXXIII in the Be I isoelectronic sequence. The corresponding atomic data for the ions Ca XVII, Cr XXI, Fe XXIII, Zn XXVII, and Se XXXI are determined by interpolation. The configurations included in the calculation of the atomic data are 2s², 2s2p, 2p², 2s3s, 2s3p, 2s3d, 2p3s, 2p3p, and 2p3d. The intensities for transitions between the lowest 20 levels of these configurations are calculated for an electron temperature equal to half the ionization potential and for electron densities equal to 10¹³, 10¹⁴, and 10¹⁵ cm⁻³.     

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.     

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.     

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.     

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 Kr XXXII

Collision strengths (Ω) have been calculated for all 7750 transitions among the lowest 125 levels belonging to the , and 2p²3? configurations of boron-like krypton, Kr XXXII, for which the Dirac Atomic R-matrix Code has been adopted. All partial waves with angular momentum J?40 have been included, sufficient for the convergence of Ω for forbidden transitions. For allowed transitions, a top-up has been included in order to obtain converged values of Ω up to an energy of 500 Ryd. Resonances in the thresholds region have been resolved in a narrow energy mesh, and results for effective collision strengths (?) have been obtained after averaging the values of Ω over a Maxwellian distribution of electron velocities. Values of ? are reported over a wide temperature range below , and the accuracy of the results is assessed. Values of ? are also listed in the temperature range , obtained from the nonresonant collision strengths from the Flexible Atomic Code.     

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.     

Breit-Pauli energy levels belonging to 2p, 2s2p, 2p, 2p3? configurations and all E1 transitions among these levels in Mg V

We present accurate oscillator strengths, line strengths and radiative rates for 1073 E1 transitions among the 86 levels belonging to 2s²2p⁴, 2s2p⁵, 2p⁶, and 2s²2p³(⁴S^o, ²D^o, ²P^o)3? configurations in Mg V. We have used 1s and 2s Hartree-Fock orbitals, re-optimized 2p on 2p³(²D^o)3s ³D^o and optimized 3s,3p,3d orbitals on real states. Sixteen additional orbitals up to 8d are optimized either as a correction to n = 3 physical orbitals or as a correlation orbital. A very large set of configurations including up to three electron promotions are used to account for all important correlation effects. All of the main five terms in the Breit-Pauli operator (except the orbit-orbit interaction) are included in order to account for the relativistic effects. Small adjustments to the diagonal elements of the Hamiltonian matrix are made to bring the calculated energies within a few cm⁻¹ of the corresponding NIST recommended data wherever available. The calculated oscillator strengths, line strengths, and radiative rates for almost all of the E1 transitions show excellent agreement with the corresponding MCDF results of Fischer. The recent results of Bhatia et al. are found to be consistently higher by 20-45%. The accuracy of the present calculation is considered to be better than the NIST accuracy ratings for various transitions.     

Oscillator strengths and transition probabilities of O II

The abundance of singly ionized oxygen, O II, in planetary nebulae provides crucial diagnostic tests for the physical conditions present in these astrophysical environments. The abundance can be determined from the absorption lines formed by the radiative processes, such as the photo-excitations reported here. Radiative transitions are obtained from a total of 708 fine structure levels of O II with , and 1/2?J?17/2. For spectral analysis oscillator strengths, line strengths, and transition probabilities (A) are presented for 51,733 electric dipole fine structure radiative transitions. The calculations were carried out in the relativistic Breit-Pauli R-matrix approximation. The transitions have been identified spectroscopically using quantum defect analysis and other criteria. The calculated energies agree with the observed energies within 5% for most of the levels. However, some relatively large differences are noted, the largest difference being 13% for the level 2s²2p²(¹D)4p(²F^o)_7/2. Most of the A values and lifetimes agree with the existing measured and calculated values. The transitions should be applicable for diagnostics as well as spectral modeling in the ultraviolet and optical regions of astrophysical and laboratory plasmas.