scholarly journals Benchmarking Current Capabilities for the Generation of Excitation and Photoionisation Atomic Data

Galaxies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 90 ◽  
Author(s):  
Catherine Ramsbottom ◽  
Connor Ballance ◽  
Ryan Smyth ◽  
Andrew Conroy ◽  
Luis Fernández-Menchero ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Cross Sections ◽  
Transition Probabilities ◽  
Energy Levels ◽  
Radiative Transition ◽  
Atomic Data ◽  
High Quality ◽  
Astronomical Instruments ◽  
First Time ◽  
Line Strengths

The spectra currently emerging from modern ground- and space-based astronomical instruments are of exceptionally high quality and resolution. To meaningfully analyse these spectra, researchers utilise complex modelling codes to replicate the observations. The main inputs to these codes are atomic data such as excitation and photoionisation cross sections, as well as radiative transition probabilities, energy levels, and line strengths. In this publication, the current capabilities of the numerical methods and computer packages used in the generation of these data are discussed. Particular emphasis is given to Fe-peak species and the heavy systems of tungsten and molybdenum. Some of the results presented to highlight certain issues and/or advances have already been published in the literature, while other sections present new recently evaluated atomic data for the first time.

scholarly journals Benchmarking Current Capabilities for the Generation of Excitation and Photoionisation Atomic Data

2018 ◽  
Author(s):  
Catherine Ramsbottom ◽  
Connor Ballance ◽  
Ryan Smyth ◽  
Andrew Conroy ◽  
Luis Fernández-Menchero ◽  
...  
Keyword(s):  
Numerical Methods ◽  
Cross Sections ◽  
Transition Probabilities ◽  
Energy Levels ◽  
Radiative Transition ◽  
Atomic Data ◽  
High Quality ◽  
Astronomical Instruments ◽  
First Time ◽  
Line Strengths

The spectra currently emerging from modern ground- and space-based astronomical instruments are of exceptionally high quality and resolution. To meaningfully analyse these spectra researchers utilise complex modelling codes to replicate the observations. The main inputs to these codes are atomic data such as excitation and photoionisation cross sections as well as radiative transition probabilities, energy levels and line strengths. In this publication the current capabilities of the numerical methods and computer packages used in the generation of these data are discussed. Particular emphasis is given to Fe-peak species and the heavy systems of tungsten and molybdenum. Some of the results presented to highlight certain issues and/or advances have already been published in the literature, while other sections present, for the first time, new recently evaluated atomic data.

scholarly journals New Radiative Atomic Data

2005 ◽  
Vol 13 ◽  
pp. 668-671
Author(s):  
Sultana N. Nahar
Keyword(s):  
Cross Sections ◽  
Transition Probabilities ◽  
Energy Levels ◽  
Radiative Transition ◽  
Dielectronic Recombination ◽  
Oscillator Strengths ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Self Consistent ◽  
Ion Recombination

AbstractLarge amount of new radiative atomic data for I) energy levels, II) oscillator strengths (f), line strengths (S), radiative transition probabilities (A), III) photoioniztion cross sections (σPI) – total and level-specific, and IV) unified total and level-specific electron-ion recombination rate coefficients, αR, including radiative and dielectronic recombination (RR and DR) are reported for various astrophysical applications. Most of the data are with fine structure. These data are not yet available from any databases. Photoionization and recombination data are self-consistent, using the same wave-function for both processes.

New Atomic Data for Astronomy: An Introductory Review

1995 ◽  
Vol 10 ◽  
pp. 570-571
Author(s):  
M.J. Seaton
Keyword(s):  
Line Profile ◽  
Cross Sections ◽  
Transition Probabilities ◽  
Energy Levels ◽  
Experimental Studies ◽  
Theoretical Work ◽  
Radiative Transition ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Collisional Rate Coefficients

Astronomers require the following basic atomic data: energy levels and wavelengths’, radiative transition probabilities; cross sections for photo-ionisation and for collisional processes; and line profile parameters. They also require processed data such as: level populations; opacities; radiation forces; line emissivities; and collisional rate-coefficients.Many of the data used by astronomers come from theoretical work. Experimental work is of importance in determining accurate wavelengths, in providing essential checks on theory for radiative probabilities and collision rates, and in the determination of line-profile parameters. Experimental studies are particularly important for processes of collisional ionisation.

Electron Collisional Excitation of S XII

1982 ◽  
Vol 37 (8) ◽  
pp. 744-751
Author(s):  
H. P. Saha ◽  
E. Trefftz
Keyword(s):  
Cross Sections ◽  
Transition Probabilities ◽  
Energy Levels ◽  
Theoretical Work ◽  
Wave Functions ◽  
Atomic Data ◽  
Collisional Excitation ◽  
Distorted Wave ◽  
Close Coupling ◽  
Target Wave

Atomic data have been obtained for the coronal ion S XII using the UCL program codes. Energy levels and radiative transition probabilities have been computed with different target descriptions allowing for configuration interaction and relativistic effects. Multi-configuration Hartree-Fock method is used to calculate the target wave functions. Collisional excitation cross sections between the 2 s2 2 p 2P0, 2s2p2 4P, 2D, 2S, 2P and the 2p34S0, 2D0, 2P0 eigenstates of S XII have been calculated using eight-state close coupling and distorted wave approximations with a target description employing a 3̄̄̄d̅ pseudo orbital. Collision strengths between the lowest five eigenstates of S XII have also been computed in five-state close coupling and distorted wave approximations for comparison. The results are compared with available theoretical work. It is found that the use of elaborate target wave functions and the choice of a more accurate scattering approximation may change the cross sections by more than 25% in some of the transitions

scholarly journals Atomic Data of Importance for Ultra-Violet and X-Ray Astronomy: A Review of Theory

1971 ◽  
Vol 2 ◽  
pp. 503-508
Author(s):  
M. J. Seaton
Keyword(s):  
Cross Sections ◽  
Transition Probabilities ◽  
Energy Levels ◽  
Ultra Violet ◽  
Wave Functions ◽  
Atomic Data ◽  
Recombination Rates ◽  
X Ray ◽  
Atomic Wave ◽  
General Aspects

In the present review I will discuss certain rather general aspects of the theory, and will leave it to other speakers to describe the results of detailed calculations. Further references to recent work are given in the Report of IAU Commission 14.1. Atomic Wave Functions and Energy LevelsIn order to calculate data of importance for ultra-violet and X-ray astronomy - wavelengths, transition probabilities, collision cross-sections, ionization and recombination rates, and line-broadening parameters - it is necessary to begin with the calculation of atomic wave functions. The interest is mainly in highly ionized systems.

scholarly journals New Transition and Energy Levels of Three-Times Ionized Krypton (Kr IV)

Atoms ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 48
Author(s):  
M. Raineri ◽  
M. Gallardo ◽  
J. Reyna Almandos ◽  
A. G. Trigueiros ◽  
C. J. B. Pagan
Keyword(s):  
Transition Probabilities ◽  
Energy Levels ◽  
Pulsed Discharge ◽  
Core Polarization ◽  
Polarization Effects ◽  
Hartree Fock ◽  
Theta Pinch ◽  
New Energy ◽  
First Time

A capillary pulsed-discharge and a theta-pinch were used to record Kr spectra in the region of 330–4800 Å. A set of 168 transitions of these spectra were classified for the first time. We extended the analysis to twenty-five new energy levels belonging to 3s23p24d, 3s23p25d even configurations. We calculated weighted transition probabilities (gA) for all of the experimentally observed lines and lifetimes for new energy levels using a relativistic Hartree–Fock method, including core-polarization effects.

Infra-red chemiluminescence II. Spectroscopic data

1960 ◽  
Vol 258 (1295) ◽  
pp. 564-575 ◽  
Keyword(s):  
Transition Probabilities ◽  
Molecular Spectroscopy ◽  
Radiative Transition ◽  
Absorption Data ◽  
A Value ◽  
Interaction Factor ◽  
Infra Red ◽  
Rotational Distribution ◽  
Vibration Rotation ◽  
First Time

The technique described in part I has been used to obtain constants of interest in molecular spectroscopy. The vibration-rotation interaction factor, F for HCl has been evaluated from the infra-red emission spectrum. The critical parameter in F is θ = M 0 / M 1 r e , where M 0 and M 1 are the first two coefficients in the electric dipole moment expansion about the equilibrium internuclear distance r e . A value of θ = + 1.12 ± 0.18 has been obtained. It is shown that for molecules with θ = +1 the total band intensity in emission is independent of the rotational distribution in the vibrational state from which the emission occurs. This has been made use of in evaluating radiative transition probabilities. For the HCl v (3-1) transition a value for | R 3 1 | 2 (= 1.60 x 10 -4 debye 2 ) was obtained for the first time. The same method yields a value of | R 2 1 | 2 / | R 2 0 | 2 = 204, in good agreement with an earlier estimate from absorption data.

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.

An Investigation on the Fine Structure Levels in the Ground State Configuration for the Antimony Anion

2014 ◽  
Vol 69 (8-9) ◽  
pp. 397-402
Author(s):  
Leyla Özdemir ◽  
Sadiye Tuna
Keyword(s):  
Fine Structure ◽  
Ground State ◽  
Transition Probabilities ◽  
Relativistic Effects ◽  
Electric Quadrupole ◽  
Radiative Transition ◽  
Ground State Configuration ◽  
Hartree Fock ◽  
First Time ◽  
State Configuration

We have investigated the correlation, relativistic, and isotope shift effects on the fine structure levels in the ground state configuration for the antimony anion ( Sb-). Energies and radiative transition probabilities (for magnetic dipole, M1, and electric quadrupole, E2) have been obtained using the multiconfiguration Hartree-Fock method within the framework of the Breit-Pauli Hamiltonian. Therefore, the most important configuration interaction and relativistic effects have been included. Comparisons with other available works are presented. For some M1 and E2 lines the considered transition probabilities are reported for the first time

scholarly journals Chromospheric and Coronal Spectra

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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