This compilation revises the 1991 listing of atomic data for the lighter elements from hydrogen to gallium. The tabulation emphasizes resonance lines, i.e., lines whose lower level is the ground state, or an excited fine-structure state of the ground term, and is restricted to wavelengths longward of the H I Lyman limit at 911.753 ?. All but the very weakest known and predicted electric-dipole transitions are included, but no forbidden lines. This paper has attempted to review all data published by the end of 2002.?????The tables contain the best data available to the author on ionization potentials, level designations, vacuum and air wavelengths, lower and upper energy levels, statistical weights, transition probabilities, natural damping constants (reciprocal lifetimes), oscillator strengths, and the often used combinations of log gf and log ?f. All ion stages with relevant classified lines are included. Individual components resulting from isotope shift and hyperfine structure are listed explicitly for certain species. The accompanying text provides references, explanations for the critical selection of data, and notes indicating where new measurements or calculations are needed.?????This compilation should be particularly useful in the analysis of interstellar and quasar absorption lines and other astrophysical sites where the density of particles and radiation is low enough to excite only the lowest atomic levels. The data also are relevant to the study of stellar atmospheres, and gaseous nebulae.?????An Appendix summarizes new data relevant to the similar compilation in Paper II for the elements germanium to uranium.

https://iopscience.iop.org/article/10.1086/377639/pdf

Atomic Data for Resonance Absorption Lines. III. Wavelengths Longward of the Lyman Limit for the Elements Hydrogen to Gallium

One of the most significant developments in computational atomic and molecular physics in recent years has been the introduction of B-spline basis sets in calculations of atomic and molecular structure and dynamics. B-splines were introduced in applied mathematics more than 50 years ago, but it has been in the 1990s, with the advent of powerful computers, that the number of applications has grown exponentially. In this review we present the main properties of B-splines and discuss why they are useful to solve different problems in atomic and molecular physics. We provide an extensive reference list of theoretical works that have made use of B-spline basis sets up to 2000. Among these, we have focused on those applications that have led to the discovery of new interesting phenomena and pointed out the reasons behind the success of the approach.

https://iopscience.iop.org/article/10.1088/0034-4885/64/12/205/pdf

Applications of B-splines in atomic and molecular physics

The current state of the theory and its application to low-energy electron-molecule collisions is reviewed. The emphasis is on elastic scattering and vibrational and rotational excitation of small diatomic and polyatomic molecules. New and traditional theoretical approaches are described, and the results of calculations are compared with existing experimental measurements.

The theory of electron-molecule collisions

We present radial velocities, equivalent widths, model atmosphere parameters, and abundances or upper limits for 53 species of 48 elements derived from high resolution optical spectroscopy of 313 metal-poor stars. A majority of these stars were selected from the metal-poor candidates of the HK Survey of Beers, Preston, and Shectman. We derive detailed abundances for 61% of these stars for the first time. Spectra were obtained during a 10 yr observing campaign using the Magellan Inamori Kyocera Echelle spectrograph on the Magellan Telescopes at Las Campanas Observatory, the Robert G. Tull Coude Spectrograph on the Harlan J. Smith Telescope at McDonald Observatory, and the High Resolution Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We perform a standard LTE abundance analysis using MARCS model atmospheres, and we apply line-by-line statistical corrections to minimize systematic abundance differences arising when different sets of lines are available for analysis. We identify several abundance correlations with effective temperature. A comparison with previous abundance analyses reveals significant differences in stellar parameters, which we investigate in detail. Our metallicities are, on average, lower by ≈0.25 dex for red giants and ≈0.04 dex for subgiants. Our sample contains 19 stars with [Fe/H] ≤–3.5, 84 stars with [Fe/H]more » ≤–3.0, and 210 stars with [Fe/H] ≤–2.5. Detailed abundances are presented here or elsewhere for 91% of the 209 stars with [Fe/H] ≤–2.5 as estimated from medium resolution spectroscopy by Beers, Preston, and Shectman. We will discuss the interpretation of these abundances in subsequent papers.« less

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A search for stars of very low metal abundance. vi. detailed abundances of 313 metal-poor stars*

We present element-to-element abundance ratios measured from high dispersion spectra for 150 field subdwarfs and early subgiants with accurate Hipparcos parallaxes (errors <20%). For 50 stars new spectra were obtained with the UVES on Kueyen (VLT UT2), the McDonald 2.7 m telescope, and SARG at TNG. Additionally, literature equivalent widths were taken from the works by Nissen & Schuster, Fulbright, and Prochaska et al. to complement our data. The whole sample includes both thick disk and halo stars (and a few thin disk stars); most stars have metallicities in the range −2 < (Fe/H) < −0.6. We found our data, that of Nissen & Schuster, and that of Prochaska to be of comparable quality; results from Fulbright scatter a bit more, but they are still of very good quality and are extremely useful due to the large size of his sample. The results of the present analysis will be used in forthcoming papers to discuss the chemical properties of the dissipational collapse and accretion components of our Galaxy.

/pdf/abundances-for-metal-poor-stars-with-accurate-parallaxes-i-2qcshn0650.pdf

Abundances for metal-poor stars with accurate parallaxes , I. Basic data

A calculation of the double photoionization of neon using many-body perturbation theory has permitted a quantitative study of the relative importance of various contributing effects, i.e., ground-state correlations, inelastic internal collisions, core rearrangement, and a virtual Auger transition. The results are in good agreement with experimental data. The energy distribution between two outgoing electrons and the ratio of double to single photoionization are calculated and discussed.

Double photoionization of neon

Recent many-body perturbation calculations of photoionization cross sections, H.P. Kelly relativistic many-body theory applied to highly-charged ions, W.R. Johnson multiconfiguration relativistic random-phase approximation and its applications to photoexcitation and photoionization, K-N. Huang R-matrix theory of atomic and molecular processes, P.G. Burke non-variational multiconfiguration Hartree-Fock calculations for continuum wave functions, C.F. Fischer L-squared basis function methods for the electronic continuum photoionization and some related processes, R. Moccia et al configuration-interaction approach for photoionization of two-electron and divalent atoms, T-N. Chang and X. Tang precision configuration-interaction calculation for atomic systems with an 1s-squared core, K.T. Chung hyperspherical coordinate description of single- and multiphoton processes in two-electron systems, A.F. Starace many-electron effects on Auger transitions, M.H. Chen multiple excitation processes in photoionization, J.A.R. Samson many-electron interactions in the photoionization of excited atoms and ions, F.J. Wuilleumier atomic structure effects in multiphoton processes - an experimental perspective, L.F. DiMauro and others.

Many-Body Theory of Atomic Structure and Photoionization

We present theoretical oscillator strengths for the bound-bound transitions between selected 1,3 S , 1,3 P , 1,3 D , and 1,3 F states of beryllium and magnesium atoms, determined from a simple configuration-interaction calculational procedure using a finite basis constructed from B splines. A detailed qualitative discussion is also presented on the effect of configuration interaction on the oscillator strengths for various groups of transitions.

Oscillator strengths for the bound-bound transitions in beryllium and magnesium

We present an extension of a simple configuration-interaction procedure to the photoionization of two-electron atoms. By using a finite basis set constructed from {ital B} splines, this nonvariational approach does not rely on any optimum procedure, which is often required in other more elaborate configuration-interaction calculations. The quantitative accuracy of this procedure is tested by examining the photoionization cross sections at photon energies immediately above the first ionization threshold, as well as near the doubly excited 2{ital s}2{ital p} {sup 1}{ital P} resonance structure. The {ital S}- and {ital P}-wave phase shifts for the electron-hydrogen scattering calculated with this procedure are also presented. The excellent agreement between the present calculation and other existing theoretical and experimental results, in addition to the extensive recent applications of this procedure to the bound excited states of divalent atoms, has further demonstrated the effectiveness of this simple configuration-interaction procedure.

Photoionization of two-electron atoms using a nonvariational configuration-interaction approach with discretized finite basis

Extension de la methode CI pour inclure la contribution du continuum a la matrice hamiltonienne evaluee sur un ensemble de base construit a partir d'un ensemble quasi complet d'orbitales discretes a une particule. Application a des transitions entre certains etats 1,3 S, 1,3 P et 1,3 D

Energy levels and the oscillator strengths of the Be atom determined by a configuration-interaction calculation with a finite basis set from B splines.

T. N. Chang

Papers

Double photoionization of neon

Many-Body Theory of Atomic Structure and Photoionization

Oscillator strengths for the bound-bound transitions in beryllium and magnesium

Photoionization of two-electron atoms using a nonvariational configuration-interaction approach with discretized finite basis

Energy levels and the oscillator strengths of the Be atom determined by a configuration-interaction calculation with a finite basis set from B splines.