Nitrogen Isoelectronic Sequence Research Articles

Energy levels and magnetic dipole transition parameters for the nitrogen isoelectronic sequence

Theoretical calculations of the energy levels and magnetic dipole transition parameters for the 1s22s22p3 and 1s22p5 configurations of nitrogen isoelectronic sequence with Z = 21–30 are performed using multi-congfiguration Dirac–Fock (MCDF) method. Based on the relativistic computational code GRASP2k compiled within the framework of MCDF method, the electron correlations, Breit interaction and QED effects are well treated in detail. The energy levels, line strengths and transition rates of magnetic dipole transition are obtained and compared with the experimental data available. For most cases, good agreements are achieved and the relative differences of them are less than 0.114%, 8.43% and 9.80%, respectively. The scaling laws of the fine structure splitting and transition rate are obtained on the isoelectronic sequence and the corresponding physical mechanisms are discussed. The data sets for tables are openly available at https://www.doi.org/10.57760/sciencedb.j00113.00022.

Extended calculations of level and transition properties in the nitrogen isoelectronic sequence: Cr XVIII, Fe XX, Ni XXII, and Zn XXIV

Extensive multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations are performed for 272 states of the 2s 2 2p 3 ,2 s2p 4 ,2 p 5 ,2 s 2 2p 2 3l ,2 s2p 3 3l, and 2p 4 3l (l = 0, 1, 2) configurations in the nitrogen-like ions Cr XVIII, Fe XX, Ni XXII, and Zn XXIV. Valence, core-valence, and core-core electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with data from other calculations and with experimental data from the NIST database. Lande gJ-factors; hyperfine structures; isotope shifts; and radiative electric dipole (E1), electric quadrupole (E2), and magnetic dipole (M1) transition rates are given for all ions. The accuracy of the calculated energy levels �

Effect of Electron Correlations and Breit Interactions on Ground-State Fine-Structures along the Nitrogen-Like Isoelectronic Sequence

The accurate atomic data of nitrogen and nitrogen-like ions have an importance role in fusion plasma studies and astrophysics studies. The precise calculation of fine-structures is required to obtain such atomic data. Along the whole nitrogen isoelectronic sequence, the contributions of the electron correlations, the Breit interactions and the quantum electrodynamics corrections on the ground-state fine-structures are elucidated. When Z is low, the electron correlations are important, and the Breit interactions, which cannot be neglected cause interesting anomalous fine-structure splittings. When Z is high, the electron correlations are less important, and the Breit interactions are important in addition to spin-orbit interactions for precise calculations.

Fine-Structure Splittings of Nitrogen Isoelectronic Sequence: Competitions among Spin–Orbit Interactions, Breit Interactions and Electron Correlations

Using the multi-configuration Dirac–Fock self-consistent field method and the relativistic configuration interaction method with quantum-electrodynamics corrections performed by the GRASP code, we calculate the fine-structure energy levels of the ground-state configuration (1s22s22p3) of the nitrogen isoelectronic sequence, according to the L-S coupling scheme with atomic number Z up to 22. Based on the calculated results, we elucidate the mechanism of the orderings of fine-structure energy levels of2D3/2,5/2 and 2P1/2,3/2 respectively, i.e. for 2D3/2,5/2 orderings, the competition between the spin-orbit interactions and the Breit interactions; for2P1/2,3/2 orderings, the electron correlations, especially the electron correlations owing to the 2p5 configuration interactions.

Photoionization of ions of the nitrogen isoelectronic sequence: experiment and theory for F2+ and Ne3+

Absolute photoionization measurements are reported for admixtures of the ground and metastable states of F2+ from 56.3 eV to 75.6 eV, and of Ne3+ from 89.3 eV to 113.8 eV. The 4So ground-state and the 2Do and 2Po metastable-state fractions present in the primary ion beams were estimated from photoion yield measurements near their respective threshold energies. Most of the observed resonance structure has been spectroscopically assigned. The measurements are compared with new R-matrix theoretical calculations and with those in the TOPbase astrophysical database. The systematic behaviour of the quantum-defect parameter is analysed as a function of the nuclear charge for four Rydberg series observed in both species, and compared to published data for O+ and N.

Ab initio Calculation of Electric Quadrupoleand Magnetic Dipole Transitions in Ions of the N I IsoelectronicSequence

The electric quadrupole (E2) and magnetic dipole (M1) transitionsin the nitrogen isoelectronic sequence (Z = 10–30)between the levels of the 1s22s22p3,1s22s2p4 and 1s22p5configurations are investigated. The results include wavelengths andradiative E2 and M1 transition probabilities. The stationarysecond-order many-body perturbation theory (MBPT) was used to accountfor the electron correlations. A non-local potential was used tocalculate the radial part of the effective Hamiltonian. Relativisticcorrections were included in the Breit–Pauli approximation. Thelowest-order correlation corrections to the one-body part of thespin–orbit interaction operator were alsoincluded.

Electric dipole transitions in ions of the N I isoelectronic sequence

The electric dipole transitions in the nitrogen isoelectronic sequence (Z = 10-30) between the levels of the 1s22s22p3, 1s22s2p4 and 1s22p5 configurations are considered. The stationary second-order many-body perturbation theory (MBPT) is used to account for the electron correlations. Non-local potential is used to calculate the radial part of the effective Hamiltonian. Relativistic corrections were included in the Breit-Pauli approximation. The results include energies, wavelengths, and oscillator strengths for all N-like ions in the interval Z = 10-30.

Oscillator strengths for transitions among low-lying quartet terms in the nitrogen isoelectronic sequence

We have calculated energies and transition rates for the 2s22p3 4S° ground state and a number of excited states in the isoelectronic sequence of atomic nitrogen using the multiconfiguration optimized potential model (MCOPM). The excited states include the 2s22p23s 4P, 2s2p4 4P, 2s22p23p 4D°, 2s22p23p 4P°, 2s22p23p 4S°, 2s22p23d 4F, 2s22p23d 4D and 2s22p23d 4P terms. The oscillator strengths for transitions among these terms have been calculated in both length and velocity gauge. Particular emphasis has been put on an accurate description near level crossings. Comparison with other theoretical and experimental results are made. However, the experimental data are rather sparse, and verification of many of the calculated trends against experiment is therefore not yet possible.

E2 and M1 Transition Probabilities in Ions of the Nitrogen Isoelectronic Sequence Calculated using MBPT

Forbidden electric quadrupole (E2) and magnetic dipole (M1) transitions are of extreme importance in astrophysics. Up to now the most extensive calculations for the nitrogen isoelectronic sequence have been done using the method proposed by C.J. Zeippen [1] or in MCHF approximation [2]. To account for electron correlations both these methods use a large list of configurations. We have chosen the stationary many-body perturbation theory (MBPT) [3] for the inclusion of the electron correlations. The calculations have been perfomed in the second order in the complete model space 1s22s2p3+ 1s22p5. Relativistic corrections have been accounted for in the Breit-Pauli approximation. In the Table we present probabilities for electric quadrupole W(E2) and magnetic dipole W(M1) transitions (in s−1), wavelengths λ (in A). The comparision of the results shows that our second order calculation data in the most cases are closer to term-energy corrected ones from [1].

Laser gain on 3p-3d and 3s-3p transitions and x-ray line ratios for the nitrogen isoelectronic sequence

The populations of the 72 levels belonging to the 2s22p3, 2s2p4, 2p5, 2s22p23s, 2s22p23p, and 2s22p23d configurations of the N i isoelectronic sequence have been calculated for the ions Ar xii, Ti xvi, Fe xx, Zn xxiv, and Kr xxx and for electron densities up to 1024 cm−3. Electron collisional monopole excitation from the 2s22p3 ground configuration to the 2s22p23p configuration contributes significantly to the populations of the excited levels and results in relatively large 2s22p23p populations. The population inversions and laser gain for transitions between the 2s22p23s and 2s22p23p configurations are calculated. It is also found that large population inversions and gain occur between levels in the 2s22p23p configuration and levels in the 2s22p23d configuration that cannot decay to the ground configuration by an electric dipole transition. For these potential laser transitions of the type 2s22p23p-2s22p23d, the reabsorption of the radiation from the lower laser level is less of a problem than for the 2s22p23s-2s22p23p laser transitions. The 2s22p23p 4P5/2-2s22p23d 4D7/2 and 2s22p23p 2F7/2-2s22p23d 2G9/2 transitions represent promising transitions for overcoming some of the problems of opacity in dense plasmas. At high electron densities where the excited levels become collisionally mixed, the intensities of the x-ray transitions from the 2s22p23p levels to the 2s2p4 levels decrease relative to the x-ray transitions from the 2s22p23s and 2s22p23d levels. The density dependence of these x-ray line ratios is presented.

Comparison of Theoretical and Experimental Level Values of the n = 2 Configurations in the Nitrogen Isoelectronic Sequence

Observed level intervals within and between the configurations 2s2 2p3, 2s2p4 and 2p5 of the nitrogen sequence are compared with the corresponding theoretical values derived from the tables of Cheng, Kim and Desclaux. The differences are expressed by suitable functions of Z which give the systematic correction to the theoretical values and reveal the accidental errors in the experimental values. The technique is the same as was used in previous examinations of the Li, Be, B, O and F sequences. The results are summarized in tables of recommended level values (Z = 10-36) and recalculated wavelengths.

Theoretical atomic structure and electron scattering data for ions in the nitrogen isoelectronic sequence: MG VI, Si VIII, S x, A XII and Ca XIV

Theoretical atomic structure and electron scattering data for ions in the nitrogen isoelectronic sequence: MG VI, Si VIII, S x, A XII and Ca XIV

Transitions 2s'2pk -2s2p"I of the N i and C i Isoelectronic Sequences

view Abstract Citations (29) References (9) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Transitions 2s'2pk -2s2p"I of the N i and C i Isoelectronic Sequences Feldman, U. ; Doschek, G. A. ; Cowan, R. D. ; Cohen, Leonard Abstract Transitions of the type +1 have been identified for the elements from titanium through iron for ions of the nitrogen isoelectronic sequence and for the elements titanium through nickel for ions of the carbon isoelectronic sequence. Wavelengths, intensity estimates and energies are given. The lines were identified from EUV spectra obtained from laser-produced plasmas. The energy differences of levels of the ground configuration for the C I isoelectronic sequence are compared with extrapolations based on semiempirical equations derived by Edlen. Wavelengths of forbidden Fe XXI lines that can be seen in low-density plasmas such as solar flare plasmas are predicted. The laser plasma spectrum is briefly compared with available solar flare spectra. Subject headings: flares, solar - line identifications - spectra, laboratory - spectra, ultraviolet Publication: The Astrophysical Journal Pub Date: March 1975 DOI: 10.1086/153445 Bibcode: 1975ApJ...196..613F full text sources ADS |