Oscillator strengths and transition probabilities for allowed and forbidden transitions in Fe XIX

An extensive set of oscillator strengths, line strengths, and radiative decay rates for the allowed and forbidden transitions in Fe XIX is presented. They correspond to 1626 fine structure levels of total angular momenta 0≤J≤8 of even and odd parities with 2≤n≤10, 0≤l≤9, 0≤L≤10, and (2S+1)=1, 3, 5. In contrast, the compiled table of the National Institute for Standards and Technology (NIST) lists only 63 observed levels. A total of 289,291 electric dipole allowed transitions are presented. They were obtained in the close coupling approximation using the relativistic Breit-Pauli R-matrix method. The wavefunction expansion included 15 levels of the configurations 2s²2p³, 2s2p⁴, and 2p⁵ of the Fe XX core. The calculated fine structure levels are assigned with spectroscopic identifications using quantum defect analysis. Comparison with the observed energies shows very good agreement, the largest difference being less than 4%. The transitions also compare well with the compiled data by NIST and recent calculations. The forbidden transitions of the electric quadrupole and octupole, and magnetic dipole and quadrupole, type are presented for the 379 levels of the configurations 2s²2p⁴, 2s2p⁵, 2p⁶, 2s²2p³3s, 2s²2p³3p, 2s²2p³3d, 2s²2p³4s, 2s²2p³4p, 2s²2p³4d, 2s²2p³4f, 2s2p⁴3s, 2s2p⁴3p, 2s2p⁴3d, 2s2p⁴4s, 2s2p⁴4p, and 2s²2p²3s² of Fe XIX. They correspond to a total of 66,619 transitions. These results have been obtained from relativistic Breit-Pauli atomic structure calculations using the program SUPERSTRUCTURE. The forbidden transition probabilities show very good agreement with those compiled by NIST.     

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.     

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.     

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.     

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.     

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.     

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.     

Energy levels,lifetimes, wavelengths,and transition probabilities of Fe XIV

Energy levels and lifetimes are reported for all the states of the n = 3 odd and even complexes of Fe XIV, as well as the 2s²4l²L states. Data for selected allowed (E1) and forbidden (E2, M1, and M2) transitions between these states are also reported. The results have been calculated using the multiconfiguration Hartree-Fock method with a Breit-Pauli relativistic correction.     

Wavelengths,transition probabilities,and oscillator strengths for M-shell transitions in Co-, Ni-, Cu-, Zn-, Ga-, Ge-, and Se-like Au ions

Wavelengths, transition probabilities, and oscillator strengths have been calculated for M-shell electric dipole transitions in Co-, Ni-, Cu-, Zn-, Ga-, Ge-, and Se-like Au ions. The fully relativistic multiconfiguration Dirac–Fock method, taking quantum electrodynamical effects and the Breit correction into account, was used in the calculations. Calculated energy levels of M-shell excited states for Cu-, Zn-, Ga-, Ge-, and Se-like Au ions from the method were compared with available theoretical and experimental results, and good agreement with them was achieved.     

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.     

Transition probabilities and branching ratios for electric-dipole transitions between arbitrary levels of hydrogen-like atoms

Transition probabilities and branching ratios in hydrogen-like atoms due to electric-dipole transitions are tabulated for the initial principal and angular-momentum quantum numbers n′l′, and final principal and angular-momentum quantum numbers nl. The electric-dipole matrices are evaluated in parabolic coordinates, and by a transformation their values in spherical coordinates are found. In Table I transition probabilities for transitions n′l′ → n and n′ → n given.Branching ratios are tabulated in Table II for transitions n′l′ → n and n′ → n, while in Table III these ratios are tabulated for transitions n′l′ → nl and n′ → nl.The lifetime of an excited state nl can be expressed as (μZ⁴)^?1c_nln³l², where μ and Z are the reduced mass and nuclear charge of the hydrogen-like atom, and c_l is a slowly varying coefficient of n and l, approaching a constant as n,l → ∞. Values of c_nl are given in Table IV.     

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.     

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.     

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.     

Electric quadrupole transition probabilities and line strengths of Ti

Electric quadrupole transition probabilities and line strengths have been calculated using the weakest bound electron potential model for sodium-like titanium, considering many transition arrays. We employed numerical Coulomb approximation and non-relativistic Hartree–Fock wavefunctions for the expectation values of radii in determination of parameters of the model. The necessary energy values have been taken from experimental data in the literature. The calculated electric quadrupole line strengths have been compared with available data in the literature and good agreement has been obtained. Moreover, some electric quadrupole transition probability and line strength values not existing in the literature for some highly excited levels have been obtained using this method.     

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.     

Transition strengths B(E2) in the yrast bands of doubly even nuclei

Experimental data on absolute E2 transition strengths in the yrast bands of even-even nuclei are summarized in a table. In diagrams, the moments of inertia $\text{J}$(I → I ? 2) and the E2 transition moments Q₀(I → I ? 2) derived for each nucleus are presented versus (khω)² (ω is the rotational frequency). Data available up to May 1980 have been included.     

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.     

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.