Spectral line list of potential cosmochronological interest deduced from new calculations of radiative transition rates in singly ionized thorium (Th ii)

2020 ◽  
Vol 496 (4) ◽  
pp. 4507-4516 ◽  
Author(s):  
S Gamrath ◽  
M R Godefroid ◽  
P Palmeri ◽  
P Quinet ◽  
K Wang
Keyword(s):  
Spectral Line ◽  
Radiative Decay ◽  
Energy Levels ◽  
Radioactive Decay ◽  
Wavelength Region ◽  
Radiative Transition ◽  
Spectral Lines ◽  
Oscillator Strengths ◽  
Hartree Fock ◽  
Stellar Ages

ABSTRACT In this work, we report a list of 91 strong Th ii spectral lines in the visible wavelength region that could be used as cosmochronometers in future investigations to determine stellar ages from thorium radioactive decay. This list was established on the basis of a pseudo-relativistic Hartree–Fock model including core-polarization corrections (HFR+CPOL) allowing us to compute the corresponding radiative decay parameters, the latter being found to be in good overall agreement with the most accurate experimental data when available. Besides this semi-empirical approach, the fully relativistic ab initio multiconfiguration Dirac–Hartree–Fock (MCDHF) method was attempted, showing large discrepancies with both the present HFR+CPOL and the most recent experimental oscillator strengths, although the calculated wavelengths from theoretical energy levels agreed with observed spectral line wavelengths within 2.4  per cent.

scholarly journals Semiclassical perturbation Stark shifts of singly charged argon spectral lines

2019 ◽  
Vol 488 (2) ◽  
pp. 2473-2479
Author(s):  
Rafik Hamdi ◽  
Nabil Ben Nessib ◽  
Sylvie Sahal-Bréchot ◽  
Milan S Dimitrijević
Keyword(s):  
Energy Levels ◽  
Relativistic Correction ◽  
Spectral Lines ◽  
Oscillator Strengths ◽  
Perturbation Approach ◽  
Hartree Fock ◽  
Calculated Energy ◽  
Impact Approximation ◽  
Singly Charged ◽  
Experimental Values

AbstractUsing semiclassical perturbation approach in impact approximation, Stark shifts for singly charged argon (Ar ii) spectral lines have been calculated. Energy levels and oscillator strengths needed for this calculation were determined using Hartree–Fock method with relativistic correction (HFR). We compare our results with experimental values for 100 spectral lines. We also present results as a function of temperature for 161 spectral lines for collisions with electrons, protons, singly charged helium and singly charged argon. This work extends our previous one.

Energy levels and spectral lines for Ge-like Zr, Nb and Tc ions

2020 ◽  
Author(s):  
Miao Wu ◽  
Zhen-Cen He
Keyword(s):  
Quantum Electrodynamics ◽  
Transition Probabilities ◽  
Theoretical Calculations ◽  
Energy Levels ◽  
Spectral Lines ◽  
Oscillator Strengths ◽  
Hartree Fock ◽  
Experimental Values ◽  
Theoretical Results ◽  
Line Strengths

The energy levels, transition probabilities, oscillator strengths, line strengths and wavelengths of Ge-like Zr, Nb and Tc ions have been calculated using the multiconfiguration Dirac-Hartree-Fock method. The Breit interactions and quantum electrodynamics correction were taken into account. The calculated values of energy levels and wavelengths have been compared with other theoretical calculations and available experimental values, good agreements are achieved for most of the energy levels and wavelengths calculated. The number of energy levels and wavelengths considered is larger than that of any other theoretical calculations. And the transition probabilities, line strengths are also given where no other theoretical results and experimental values are available.

Revised analysis of singly ionized tellurium: Te II

2009 ◽  
Vol 87 (12) ◽  
pp. 1255-1268 ◽  
Author(s):  
A. Tauheed ◽  
Y. N. Joshi ◽  
M. Steinitz
Keyword(s):  
Energy Levels ◽  
Wavelength Region ◽  
Normal Incidence ◽  
Spectral Lines ◽  
Tellurium Atom ◽  
Hartree Fock ◽  
New Energy ◽  
Final Interpretation ◽  
Configuration Interaction Calculations ◽  
State Configuration

Tellurium spectra were recorded on a 3 m normal incidence vacuum spectrograph in the spectroscopy laboratory of St. Francis Xavier University using a triggered spark light source. The spectrum of the singly ionized tellurium atom was investigated in the wavelength region 746–1838 Å using Hartree–Fock configuration interaction calculations involving 5s25p3, 5s5p4, 5s25p2 (5d + 6d + 7d + 8d + 6s + 7s + 8s + 9s) configurations. Earlier analysis by Handrup and Mack has been revised, and 27 new energy levels have been added, to complete the 5s25p3, 5s25p2 (5d + 6d + 6s + 7s) configurations. Now five levels of the ground-state configuration and 78 of the excited configurations are known. Two hundred and nineteen spectral lines have been classified in this spectrum. Least squares fitted parametric calculations were used for the final interpretation and LS percentage compositions. The wavelength accuracy of our measurement for unblended and sharp lines is ±0.005 Å.

scholarly journals Extended theoretical transition data in C i–iv

2021 ◽  
Vol 502 (3) ◽  
pp. 3780-3799
Author(s):  
W Li ◽  
A M Amarsi ◽  
A Papoulia ◽  
J Ekman ◽  
P Jönsson
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Internal Validation ◽  
Hartree Fock ◽  
Relativistic Configuration ◽  
The Difference ◽  
The One ◽  
Relative Differences

ABSTRACT Accurate atomic data are essential for opacity calculations and for abundance analyses of the Sun and other stars. The aim of this work is to provide accurate and extensive results of energy levels and transition data for C i–iv. The Multiconfiguration Dirac–Hartree–Fock and relativistic configuration interaction methods were used in this work. To improve the quality of the wavefunctions and reduce the relative differences between length and velocity forms for transition data involving high Rydberg states, alternative computational strategies were employed by imposing restrictions on the electron substitutions when constructing the orbital basis for each atom and ion. Transition data, for example, weighted oscillator strengths and transition probabilities, are given for radiative electric dipole (E1) transitions involving levels up to 1s22s22p6s for C i, up to 1s22s27f for C ii, up to 1s22s7f for C iii, and up to 1s28g for C iv. Using the difference between the transition rates in length and velocity gauges as an internal validation, the average uncertainties of all presented E1 transitions are estimated to be 8.05 per cent, 7.20 per cent, 1.77 per cent, and 0.28 per cent, respectively, for C i–iv. Extensive comparisons with available experimental and theoretical results are performed and good agreement is observed for most of the transitions. In addition, the C i data were employed in a re-analysis of the solar carbon abundance. The new transition data give a line-by-line dispersion similar to the one obtained when using transition data that are typically used in stellar spectroscopic applications today.

scholarly journals Study of opacity broadening in spectral lines for helium like ions in aluminum plasma which produced by laser

2011 ◽  
Vol 8 (1) ◽  
pp. 54-58
Author(s):  
Baghdad Science Journal
Keyword(s):  
Theoretical Analysis ◽  
Spectral Line ◽  
Quantum Number ◽  
Plasma Density ◽  
Energy Levels ◽  
Spectral Lines ◽  
Aluminum Plasma

A theoretical analysis studied was performed to study the opacity broadening of spectral lines emitted from aluminum plasma produced by Nd-YLF laser. The plasma density was in the range 1028-1026 )) m-3 with length of plasma about ?300) m) , the opacity was studied as function of plasma density & principle quantum number. The results show that the opacity broadening increases as plasma density increases & decreases with the spacing between energy levels of emission spectral line.

Ab initio predictions of the zero field splittings and the singlet–triplet transition strengths for the n → π* transition of selenoformaldehyde

1993 ◽  
Vol 71 (10) ◽  
pp. 1706-1712 ◽  
Author(s):  
D.C. Moule ◽  
L. Chantranupong ◽  
R.H. Judge ◽  
D.J. Clouthier
Keyword(s):  
Energy Levels ◽  
Random Phase ◽  
Open Shell ◽  
Oscillator Strengths ◽  
Basis Set ◽  
Zero Field ◽  
Zero Field Splitting ◽  
Hartree Fock ◽  
Lower Valence ◽  
Polarization Functions

The energy levels of the lower valence and Rydberg states of selenoformaldehyde, CH2Se, have been calculated by the SCF/CI method. Wavefunctions for the ROHF (restricted open shell Hartree–Fock) states were obtained with the Binnings–Curtis double-ζ basis set, augmented with Rydberg and polarization functions. Configuration interaction was applied to the parent configurations, PCMO (parent configuration molecular orbital). Oscillator strengths were evaluated for the allowed electric dipole transitions by the RPA (random phase approximation), and SOPPA (second-order polarization propagator approximation) methods. The spin-orbit contribution to the zero field splitting of the first triplet state, 3A2(n,π*) as well as the oscillator strengths to the three spin components were calculated by perturbation theory. These calculations predict that the Sx, Sy, and Sz components are shifted by −96.091,−96.707, and + 29.167 cm−1, respectively, from their unperturbed position. The oscillator strengths for the three components fx, fy, and fz of the 3A2(n,π*) ← 1A1(g.s.) transition were calculated to be 3.45 × 10−7, 1.15 × 10−7, and 173.0 × 10−7.

scholarly journals Current Status and Developments of the Atomic Database on Rare-Earths at Mons University (DREAM)

Atoms ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 18 ◽  
Author(s):  
Pascal Quinet ◽  
Patrick Palmeri
Keyword(s):  
Rare Earths ◽  
Spectral Lines ◽  
Oscillator Strengths ◽  
Current Status ◽  
Time Resolved ◽  
Hartree Fock ◽  
Lanthanide Atoms ◽  
Experimental Values ◽  
Theoretical Results ◽  
Good Agreement

The main purpose of the Database on Rare Earths At Mons University (DREAM) is to provide the scientific community with updated spectroscopic parameters related to lanthanide atoms (Z = 57–71) in their lowest ionization stages. The radiative parameters (oscillator strengths and transitions probabilities) listed in the database have been obtained over the past 20 years by the Atomic Physics and Astrophysics group of Mons University, Belgium, thanks to a systematic and extensive use of the pseudo-relativistic Hartree-Fock (HFR) method modified for taking core-polarization and core-penetration effects into account. Most of these theoretical results have been validated by the good agreement obtained when comparing computed radiative lifetimes and accurate experimental values measured by the time-resolved laser-induced fluorescence technique. In the present paper, we report on the current status and developments of the database that gathers radiative parameters for more than 72,000 spectral lines in neutral, singly-, doubly-, and triply-ionized lanthanides.

scholarly journals Transition Parameters for Doubly Ionized Lanthanum

2012 ◽  
Vol 2012 ◽  
pp. 1-15 ◽  
Author(s):  
Betül Karaçoban ◽  
Leyla Özdemir
Keyword(s):  
Least Squares ◽  
Configuration Interaction ◽  
Electric Dipole ◽  
Transition Probabilities ◽  
Energy Levels ◽  
Relativistic Effects ◽  
Oscillator Strengths ◽  
Least Squares Fitting ◽  
Hartree Fock

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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