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 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 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.     

Excitation energies, radiative and autoionization rates, dielectronic satellite lines, and dielectronic recombination rates for excited states of Na-like W from Ne-like W

Energy levels, radiative transition probabilities, and autoionization rates for and states in Na-like tungsten (W⁶³⁺) are calculated. Cowan’s relativistic Hartree-Fock method, the relativistic multiconfiguration method implemented in the Hebrew University Lawrence Livermore Atomic Code, and the relativistic many-body perturbation theory method, are used. Autoionizing levels above the threshold 1s²2s²2p⁶ are considered. It is found that configuration mixing plays an important role for all atomic characteristics. Also strong mixing between states with 2s and 2p holes (1s²2s²2p⁵3l₁nl₂+1s²2s2p⁶3l₃nl₄) occurs. Branching ratios relative to the first threshold and intensity factors are calculated for satellite lines, and dielectronic recombination (DR) rate coefficients are determined for the excited states. It is shown that the contribution of the highly excited states is very important for calculation of total DR rates. Contributions from the autoionizing states and to the DR rate coefficients are estimated by extrapolation of all atomic parameters. The orbital angular momentum (l) distribution of the rate coefficients shows a peak at l=2. The total DR rate coefficient is derived as a function of electron temperature. The dielectronic satellite spectra of W⁶³⁺ are important for L-shell diagnostics of very high-temperature laboratory plasmas such as future ITER fusion plasmas.     

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.     

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 in Ag-like (4d4f, 4d5? (? = 0-3)), Pd-like (4d4f [J = 1], 4d5p [J = 1], 4d5f [J = 1]), and Rh-like (4d [J = 5/2, 3/2]) ions with Z ? 86

Relativistic perturbation theory with a model potential is used for the calculation of energy levels of the states 4f_5/2, 4f_7/2, 5s_1/2, 5p_1/2, 5p_3/2, 5d_3/2, 5d_5/2, 5f_5/2, and 5f_7/2 above the 1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶4d¹⁰ core, with one vacancy , in the same core, in the silver and rhodium isoelectronic sequences with the maximum nuclear charge Z = 86. The method of extrapolation of the model potential parameter is applied to calculate one-electron and one-vacancy wavefunctions. The wavefunctions of Ag- and Rh-like ions were used to calculate the energies of resonance transitions to the ground state ¹S₀ in Pd-like ions. Good agreement between the theoretical and the experimental energies of the resonance transitions in Pd-like ions indicates the reliability of the results obtained.     

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.     

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.     

380 keV proton irradiation effects on photoluminescence of Eu-doped GaN

The effect of 380 keV proton irradiation on the photoluminescence (PL) properties has been investigated for undoped and Eu-doped GaN. As the proton irradiation exceeds , a drastic decrease of PL intensity of the near band-edge emission of undoped GaN was observed. On the other hand, for Eu-doped GaN, the PL emission corresponding to the ⁵D₀→⁷F₂ transition in Eu³⁺ kept the initial PL intensity after the proton irradiation up to . Present results, together with our previous report on electron irradiation results, suggest that Eu-doped GaN is a strong candidate for light emitting devices in high irradiation environment.     

Study of the electronic structures of oxygen doped in LiBaF3 crystal

The most likely substituting positions of impurity oxygen ions in LiBaF₃ crystals are studied using the general utility lattice program (GULP). The calculated results indicate that the main defect model is [] in the O:LiBaF₃ crystal. The electronic structures of the LiBaF₃ crystal with the defect [] are calculated using the DV-Xα method. It can be concluded from the electronic structures that the LiBaF₃ crystal with the defect [] will exhibit a 217-280 nm absorption band and the impurity oxygen will decrease core-valence luminescence yield.