Electric-dipole allowed and intercombination transitions among the 3d, 3d4s and 3d4p levels of Fe IV

Oscillator strengths and transition rates for the electric-dipole (E1) allowed and intercombination transitions among 3d⁵, 3d⁴4s and 3d⁴4p levels of Fe IV are calculated using the CIV3 code of Hibbert and coworkers. Using the Hartree-Fock functions up to 3d orbitals we have also optimized 4s, 4p, 4d, 4f, 5s, 5p and 5d orbitals of which 4s and 4p are taken to be spectroscopic and the remaining orbitals represent corrections to the spectroscopic orbitals or the correlation effects. The J-dependent levels of 108 LS states are included in the calculation and the relativistic effects are accounted for via the Breit-Pauli operator. Configurations are chosen in two steps: (a) two promotions were allowed from the 3p, 3d, 4s and 4p subshells, using all the orbitals; and (b) selective promotions from the 3s subshell are included, but only to the 3s and 4s orbitals. The ab initio fine-structure levels are then fine tuned to reproduce observed energy levels as closely as possible, and the resulting wavefunctions are used to calculate oscillator strengths and transition rates for all possible E1 transitions. For many of these transitions, the present results show good agreement between the length and velocity forms while for some transitions, some large disagreements are found with other available results. The complete list of weighted oscillator strengths, transition rates, and line strengths for transitions among the fine structure levels of the three lowest configurations are presented in ascending order of wavelength.     

Electron collisions with Fe-peak elements: Forbidden transitions between the low lying valence states 3d, 3d4s, and 3d4p of Fe III

Effective collision strengths are presented for the Fe-peak element Fe III at electron temperatures (T_e in degrees Kelvin) in the range 2 × 10³ to 1 × 10⁶. Forbidden transitions results are given between the 3d⁶, 3d⁵4s, and the 3d⁵4p manifolds applicable to the modeling of laboratory and astrophysical plasmas.     

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.     

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.     

Energies and E1, M1, E2, M2 transition rates for states of the 2s22p, 2s2p2, and 2p3 configurations in boron-like ions between N III and Zn XXVI

Energies, E1, M1, E2, M2 transition rates, line strengths, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the (1s²)2s²2p, 2s2p², and 2p³ configurations in all boron-like ions between N III and Zn XXVI. Valence, core–valence, and core–core correlation effects were accounted for through single–double multireference (SD-MR) expansions to increasing sets of active orbitals.     

Beam-foil study of 2p43s, 3p and 3d configurations in S VIII

The spectrum of seven times ionised sulphur, S VIII, has been observed from 450 to 1150 Å. About 30 lines have been identified as combinations between levels of the 2s²2p⁴3s, 3p and 3d configurations. The identifications are supported by isoelectronic comparisons along the FI isoelectronic sequence.     

Theoretical energy level spectra and transition data for 4p4d, 4p4d4f,and 4p4d configurations of W

The ab initio   quasirelativistic Hartree–Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions is used to derive transition data for a multicharged tungsten ion. The configuration interaction method is applied to include electron correlation effects. The relativistic effects are taken into account in the Breit–Pauli approximation for quasirelativistic Hartree–Fock radial orbitals. The energy level spectra, radiative lifetimes and Lande g$g$-factors are calculated for the 4p⁶4d², 4p⁶4d4f, and 4p⁵4d³ configurations of the ion W³⁶⁺. The transition wavelengths, spontaneous transition probabilities, oscillator strengths, and line strengths for the electric dipole, electric quadrupole, electric octupole, and magnetic dipole transitions among the levels of these configurations are tabulated.     

collision strengths for innershell excitation of Li-like ions from the 1s23l levels to the 1s2l′3l″ levels

Results are given for collision strengths, collision rates, transition energies, and electric-dipole line strengths for innershell excitation from the 1s²3l levels to all levels of the 1s2l′3l″ configurations in Li-like ions with nuclear charge number Z in the range 6 ? Z ? 74. The results include the effects of configuration mixing, parentage mixing, and intermediate coupling. A Coulomb-Bornexchange method is used in calculating the collision strengths. The results for collision strengths and line strengths are expressed conveniently in terms of the Z-scaled hydrogenic ion collision strengths and line strength, respectively, together with coefficients that are functions of the target ion mixing coefficients.     

The energy levels and radiative transition probabilities for electric quadrupole and magnetic dipole transitions among the levels of the ground configuration, [Kr]4d4f, of W

Large-scale multiconfiguration Hartree-Fock and Dirac-Fock calculations have been performed for the ground configuration, [Kr]4d¹⁰4f⁴, energy levels of the W²⁴⁺ ion. The relativistic corrections were taken into account in the quasirelativistic Breit-Pauli and fully relativistic Breit (taking into account QED effects) approximations. The role of correlation, relativistic, and QED corrections is discussed. Line strengths, oscillator strengths, and transition probabilities in the Coulomb and Babushkin gauges are presented for the electric quadrupole (E2) transitions among these levels. The magnetic dipole transitions are also investigated. Dependence of the E2 transition probabilities on the gauge condition of the electromagnetic field potential is studied as well.     

Experimental values of transition probabilities for 2s22p3-2s2p4 transitions along the N I like sequence

Transition probabilities for the 2s²2p³²D/²P-2s2p⁴²P and 2s²2p³²D/²P-2s2p⁴²D transitions in O II, F III, Ne IV and Si VIII ions have been determined. The results are compared with atomic structure calculations. A good overall agreement with data based on the NCMET method is observed which underlines the importance of electron correlations for the investigated decay processes     

Energies and E1, M1, E2, and M2 transition rates for states of the 2s2p, 2s2p,and 2p configurations in nitrogen-like ions between F III and Kr XXX

Based on relativistic wavefunctions from multiconfiguration Dirac–Hartree–Fock and configuration interaction calculations, E1, M1, E2, and M2 transition rates, weighted oscillator strengths, and lifetimes are evaluated for the states of the (1s²)2s²2p³,2s2p⁴, and 2p⁵ configurations in all nitrogen-like ions between F  III and Kr  XXX. The wavefunction expansions include valence, core–valence, and core–core correlation effects through single–double multireference expansions to increasing sets of active orbitals. The computed energies agree very well with experimental values, with differences of only 300–600 cm⁻¹ for the majority of the levels and ions in the sequence. Computed transitions rates are in close agreement with available data from MCHF-BP calculations by Tachiev and Froese Fischer [G.I. Tachiev, C. Froese Fischer, A&A 385 (2002) 716].     

Theoretical energy level spectra and transition data for 4p4d, 4p4f and 4p4d configurations of W ion

The ab initio quasirelativistic Hartree-Fock method developed specifically for the calculation of spectral parameters of heavy atoms and highly charged ions was applied to determine atomic data for tungsten ions. The correlation effects were included by adopting the configuration interaction method. The Breit-Pauli approximation for quasirelativistic Hartree-Fock radial orbitals was employed to take into account relativistic effects. The energy level spectra, radiative lifetimes, Lande factors g were calculated for the 4p⁶4d, 4p⁶4f and 4p⁵4d² configurations of W³⁷⁺ ion. The atomic data, namely, the transition wavelengths, spontaneous emission rates and oscillator strengths for the electric dipole, electric quadrupole and magnetic dipole transitions among and within the levels of these configurations are tabulated.     

Studies of 1s2s 3S-1s2p 3P transitions in helium-like Ne8+ recoil ions using photographic spectroscopy

This work describes the application of the technique of photographic VUV spectroscopy to accurate measurement of the wavelength of the theoretically interesting 1s2s ³S₁-1s2p ³P₂ transition in helium-like Ne⁸⁺ in a recoil ion source. Good resolution is obtained, and a preliminary value of 124.815±0.002 nm is found for the wavelength.     

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.     

Collision strengths and line strengths for fine-structure transitions between the 2la2lb configurations and the 2l′a3l′b configurations in Be-like ions

Collision strengths have been calculated for all fine-structure transitions between the levels of the 2l_a2l_b configurations and those of the 2l′_a3l′_b configurations in 17 Be-like ions with nuclear charge number Z in the range 10 ? Z ? 74 for nine impact-electron energies ? in threshold units in the range 1 ? ? ? 15. Fits of all the collision strengths to simple functions of ? that are readily integrated over a Maxwellian distribution to obtain collision rates are given. Also given are the results for transitions between energy terms. In addition, the electric-dipole radiative line strengths and the transition energies are listed. The method used is a Coulomb-Born-exchange method that is well suited for handling many members of an isoelectronic sequence simultaneously. The calculations include both configuration mixing and intermediate coupling effects.     

Analysis of the Ne- like 2p~53s,3p and3d configurations of Br XXVI

FollowingthefirstdemonstrationofsoftX-rayinNe-likeSe24 manyexperimentalandtheoreticalstudiesofthestructureofNe-likeionshavebeenreported.In1994NilsenandScofieldprovidedacriticalevaluationofthewavelengthsofallobserved3s-3plineswithlaserpropertiesforionsbetw…     

Calculated wavelengths,oscillator strengths,and energy levels for n = 2−2 and 2–3 transitions in F-like ions Mg IV to Ni XX and for 3−3 and other transitions in Mg IV,Al V,and Si VI

Weighted oscillator strengths, energy levels, and wavelengths are calculated for the 2s²2p⁵-2s2p⁶, 2s²2p⁵-2²2p⁴3s, and 2s²2p⁵-2s²2p⁴3d transition arrays for F-like ions in the isoelectronic sequence from Mg IV to Ni XX and in addition for n = 3?3 and other transitions in Mg IV, Al V, and Si VI. The calculation involves the computation of ab initio values of Slater radial energy integrals using a Hartree-Fock-Relativistic computer program package, which includes configuration-interaction and applies the Blume-Watson method for spin-orbit integrals. Some of the parameters are subsequently optimized on the basis of empirical data. Adopted values are tabulated along with atomic energy level compositions.     

Calculated wavelengths and oscillator strengths for Be I, B II, C III, and N IV for n = 2−2, 2−3, 3−3, and other transitions

Calculated wavelengths and weighted oscillator strengths are listed for allowed n = 2−2, 2−3, and 3−3 transitions in ions belonging to the Be-like isoelectronic sequence between Be I and N IV. Additionally, selected transitions involving levels up to n = 5 are given. This extends previous tabulations for n = 2−3 transitions in ions (O V to Ni XXV) in the same sequence. Both projects used the same Hartree-Fock-Relativistic computer program package. The methods employed are similar in that ab initio values of Slater radial energy integrals are adjusted on the basis of empirical data but are different in that interacting configurations from complexes of principal quantum number n > 3 are included in the computations for Be I to N IV.     

Energy levels,wavelengths, and transition rates of multipole transitions (E1, E2, M1, M2) in Au and Au ions

The fully relativistic configuration interaction method of the FAC code is used to calculate atomic data for multipole transitions in Mg-like Au (Au⁶⁷⁺) and Al-like Au (Au⁶⁶⁺) ions. Generated atomic data are important in the modeling of M-shell spectra for heavy Au ions and Au plasma diagnostics. Energy levels, oscillator strengths and transition rates are calculated for electric-dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) for transitions between excited and ground states 3l−nl^′$3l-n{l}^{\prime }$, such that n=4,5,6,7$n=4,5,6,7$. The local central potential is derived using the Dirac–Fock–Slater method. Correlation effects to all orders are considered by the configuration interaction expansion. All relativistic effects are included in the calculations. Calculated energy levels are compared against published values that were calculated using the multi-reference many body perturbation theory, which includes higher order QED effects. Favorable agreement was observed, with less than 0.15% difference.     

Resolution enhancement of the 3He(d,p)4He resonance for profiling helium in solids

The use of nuclear resonances techniques for characterizing the distribution and lattice location of implanted atoms in metals is a direct and, in principle, simple method for studying helium and hydrogen gas in CTR first wall materials. However, the reaction ³He(d,p)⁴He, has a broad (350 keV) half-width in the resonance yield curve. When using a deuteron beam, under normal probing conditions, to measure helium distributions in metals, a rather low stopping power results in limited resolution of about 3 μm. In many cases resolution of a few thousand angstroms or better is necessary. We have experimentally examined two resolution enhancement methods and reported the results in a previous article. The present paper will review those results and examine limitations of resolution enhancement that are obtainable through geometrical and mathematical techniques.