Relativistic effects on the energy levels and radiative properties of He-like ions immersed in Debye plasmas

The transition parameters such as the wavelengths, weighted oscillator strengths, and transition probabilities (or rates) for the nd (n=5−9)−nf (n=4−8), nd (n=5−9)−np (n=6−9), np (n=6−9)−ns (n=6−10), and ng (n=5−8)−nf (n=4−8) electric dipole (E1) transitions of doubly ionized lanthanum (La III, Z=57) have been calculated using the relativistic Hartree-Fock (HFR) method. In this method, configuration interaction and relativistic effects have been included in the computations combined with a least squares fitting of the Hamiltonian eigenvalues to the observed energy levels. We have compared the results obtained from this work with the previously available calculations and experiments in literature. We have also reported new transitions with the weighted transition probabilities greater than or equal to 105.

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Chromospheric and Coronal Spectra

Highlights of Astronomy ◽

10.1017/s1539299600012132 ◽

1995 ◽

Vol 10 ◽

pp. 580-582

Author(s):

Carole Jordan

Keyword(s):

Transition Probabilities ◽

Energy Levels ◽

Relativistic Effects ◽

Uv Spectra ◽

Oscillator Strengths ◽

Atomic Data ◽

Recombination Rates ◽

Electron Collisions ◽

Close Coupling ◽

Radiative Processes

The interpretation of chromospheric and coronal spectra requires accurate ionization and recombination rates, collision strengths and transition probabilities. Recent projects to improve calculations of opacities in stellar interiors have led to a large amount of new atomic data. Some current and potential applications of atomic data to chromospheric and coronal spectra are mentioned below.Strong chromospheric lines are optically thick, and the solution of the radiative transfer equations can depend on atomic data for other species contributing to the background opacity. Many lines in the spectra of stars with hot coronae are excited by electron collisions, but in the cooler non-coronal giants radiative processes involving the H Lyman α and β lines become more important (see Jordan 1988a). Photo-ionization rates from ground configuration excited terms and oscillator strengths to high levels are still needed.Fe II is an important ion producing emission lines in stellar chromospheres. Several excitation mechanisms contribute to the observed spectra (Jordan 1988b). Permitted lines to the ground term and low lying metastable terms have high optical depths and transfer photons to spin forbidden lines sharing a common upper level (e.g. mults. uv 1 and uv 3 transfer photons to mults. uv 32 and 61). Line intensity ratios yield the optical depth in the optically thick lines. The strong H Ly α line in cool giants and supergiants excites high levels in Fe II, resulting in strong decays in multiplets such as uv 391 and 399. A large number of f-values are required to interpret the lines formed by these radiative processes. Nahar & Pradhan (1994) have published some results from the Opacity Project, calculated by using the close coupling method and observed energy levels (which introduce some allowance for relativistic effects). In most cases these f-values agree with experimental results and the calculations by Kurucz (1988) to within 10%. The latter are still needed for the interpretation of stellar uv spectra because of the treatment of spin-forbidden lines.

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The influence of relativistic effects on electronic energy levels in metal tetraiodides MI4 (M=Ti, Zr, Hf, Th)

Polyhedron ◽

10.1016/j.poly.2015.03.014 ◽

2015 ◽

Vol 93 ◽

pp. 1-7

Author(s):

Jennifer C. Green ◽

Russell G. Egdell

Keyword(s):

Energy Levels ◽

Relativistic Effects ◽

Electronic Energy ◽

Electronic Energy Levels

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Precise theory of the Stark effect on hydrogen- and helium-like atoms

Canadian Journal of Physics ◽

10.1139/p02-090 ◽

2002 ◽

Vol 80 (11) ◽

pp. 1401-1412 ◽

Cited By ~ 3

Author(s):

V D Ovsiannikov ◽

V G Pal'chikov

Keyword(s):

Green’S Function ◽

Green's Function ◽

Ground State ◽

Stark Effect ◽

Energy Levels ◽

Relativistic Effects ◽

Model Potential ◽

Matrix Elements ◽

Angular Momenta ◽

Relativistic Coulomb

The relativistic effects on the dipole polarizabilities and hyperpolarizabilities are considered for different kinds of energy levels in hydrogen- and helium-like atoms. The relativistic Coulomb Green's function is used for calculating the susceptibilities of the ground-state hydrogen up to terms of order (α Z)10. Both relativistic and interelectronic corrections are determined for the ground state of helium. The formulas are given for polarizability and hyperpolarizability in the relativistic "screened-charge" approximation. The anticrossing of the triplet 3PJ states with zero magnetic quantum number is studied on the basis of perturbation theory for degenerate states. General expressions are given for the dipole matrix elements, up to the fourth order in field strength, within the basis of close fine-structure substates with equal angular momenta L and different total momenta J. The calculation of the higher order matrix elements is carried out with the use of the Green's function in the model potential approximation. PACS Nos.: 31.10Dk, 31.15Ar, 31.30Jv, 32.10-f, 31.25Eb

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