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Atomic transition probabilities for about 6400 allowed and forbidden lines of S I – S XV are tabulated based on a critical evaluation of recent literature sources. The transition probabilities were obtained mainly from recent sophisticated calculations carried out with complex computer codes. These tables provide data of interest for astronomical as well as laboratory plasmas. They will also be useful for the diagnostics of plasmas encountered in fusion energy research.

We have extended our critical review of the available experimental data on Stark widths and shifts for spectral lines of non‐hydrogenic neutral atoms and positive ions by one year, including the year 2000, so that we now cover the period from 1989 through the end of 2000. Our recently completed new review represents a continuation of earlier critical reviews up to 1988. Data tables containing the selected experimental Stark broadening parameters are presented with estimated accuracies. Guidelines for the accuracy estimates, developed during the previous reviews, are summarized. The data are arranged according to elements and spectra, and these are presented in alphabetical and numerical order, respectively. A total of 77 spectra are covered, and the material on multiply charged ions has significantly increased. Comparisons with comprehensive calculations based on semi‐classical theory are made whenever possible, since the comparison with theory has often been a principal motivation for the experiments.

Atomic transition probabilities for allowed and forbidden lines of Ba I and Ba II are tabulated, based on a critical evaluation of recent literature sources. The data are presented in multiplet format and are ordered by increasing excitation energies.

With a wall-stabilized arc source, we have measured the relative line strengths for various neutral carbon lines between electronic states with angular momentum quantum numbers l = 0, 1, 2 (s, p, d) and principal quantum numbers 3, 4 and 5, in order to provide some experimental data on the spectroscopic coupling situation for this spectrum. C I is of interest because it is the first element in the periodic table for which calculations have predicted significant departures from LS-coupling line strengths for prominent transitions, while lighter atoms and ions adhere quite closely to the LS-coupling scheme. We have found indeed that for 3p-4d and 3p-5s lines the deviations of the measured line strengths from LS-coupling values become large, while the agreement with recent intermediate coupling calculations is very good.

We have measured the relative line strengths for a fairly large number of lines of the 3s-3p and 3p-3d transition arrays of N II with a wall-stabilized arc source in order to test the quality of recent advanced atomic structure calculations. We have observed significant deviations from LS coupling for weaker 3p-3d lines and have found that our measurements agree much better with recent intermediate coupling results. Also, fairly strong intersystem, or spin-forbidden, lines occur for the N II ion due to a near coincidence of the 3s${\mathrm{}}^{1}$${\mathit{P}}^{\mathit{o}}$ and 3s${\mathrm{}}^{3}$${\mathit{P}}^{\mathit{o}}$ levels. We provide experimental comparison data for two recent calculations that differ by a factor of 2 for these intersystem lines. \textcopyright{} 1996 The American Physical Society.

Critically evaluated wavelengths, energy levels, ionization energies, line classifications, oscillator strengths, and atomic transition probabilities for Mn VII to Mn XXV are tabulated. A short review of the line identifications and wavelength measurements is given for each stage of ionization. Grotrian diagrams are also presented to provide graphical overviews. The literature has been surveyed to December 1991.

Wavelengths, energy levels, ionization energies, line classifications, oscillator strengths, and atomic transition probabilities for Cr v to Cr XXIV are tabulated. A short review of the line identifications and wavelength measurements is given for each stage of ionization. Grotrian diagrams are given to provide graphical overviews. The literature has been surveyed through December 1991. §

The branching-ratio technique for radiometric calibrations in the vacuum ultraviolet is briefly reviewed. A list of transitions suitable for use of the technique is given for boron-like ions, along with pertinent data for their application.

We have examined regularities in plasma-produced line shifts (Stark shifts) by a comprehensive analysis of literature data. Since the shifts are the result of atomic collision processes, regularities are expected from general atomic structure considerations. Specifically, systematic behavior should occur for spectral series and for corresponding transitions in homologous atoms and isoelectronic ions. Also, Stark shifts should be similar for lines within multiplets and, to a lesser degree, within supermultiplets and transition arrays. Numerous examples show conclusively that the measured data exhibit these predicted regularities. When pronounced irregularities occur, they are readily explainable in terms of special circumstances in the atomic structure.

Wavelengths, energy levels, level designations, oscillator strengths, and atomic transition probabilities for the vanadium ions V VI to V XXIII are tabulated. A short review of the line identifications and wavelength measurements is given for each stage of ionization. Grotrian diagrams are also presented to provide graphical overviews. The literature has been surveyed to September 1991.

A critical review of the available experimental data on Stark widths and shifts for spectral lines of non‐hydrogenic neutral atoms and positive ions has been carried out. The review covers the period from 1983 through the end of 1988 and represents a continuation of earlier critical reviews up to 1982. Data tables containing the selected experimental Stark broadening parameters are presented with estimated accuracies. Guidelines for the accuracy estimates have been done developed during the previous reviews and are summarized. The data are arranged according to elements and spectra, and these are presented in alphabetical and numerical order, respectively. Comparisons with comprehensive calculations based either on the semiclassical theory, or—for multiply ionized atoms—on the modified semiempirical approximation, are made whenever possible, since the comparison with theory has often been a principal motivation for the experiments.

Wavelengths, energy levels, level classifications, oscillator strengths, and atomic transition probabilities of the iron ions Fe viii to Fe xxvi are critically reviewed and tabulated. Grotrain diagrams are also presented to provide graphical overviews. The literature has been surveyed to March 1988.

The status of experimental studies of the plasma broadening and shifts of non-hydrogenic neutral atom and positive ion spectral lines is reviewed, and the results of comparisons with theory are discussed. Advances in the experimental techniques and diagnostic procedures are also reviewed.

In order to test the validity of the [ital LS]-coupling approximation for light elements, the line-intensity ratios of the 3[ital s]-3[ital p] and 3[ital p]-3[ital d] multiplets in C II through FV and C II through Ne VI, respectively, have been investigated experimentally with emission sources. Also, calculations with multiconfiguration Dirac-Fock wave functions have been performed. Within the errors of the experimental procedure, no significant violations of the [ital LS]-coupling approximation were found for the lines of the 3[ital s]-3[ital p] and 3[ital p]-3[ital d] multiplets in C II through F V . However, in the case of Ne VI, small deviations of measured intensities from those obtained by applying the [ital LS]-coupling approximation were observed.

Accurate atomic collision and structure data are an essential ingredient for a wide range of research fields as well as for major technological applications. Areas from laboratory physics to quantum processing, from plasma research applications in nuclear fusion to lighting research, as well as astrophysics and cosmology, depend critically on such data. But many data still exhibit inconsistencies and inaccuracies, so that significant efforts are continuing to improve the data quality. Additionally, a substantial body of much-needed data is absent from the published literature and from databases. Appreciable progress is being made, aided by greatly improved, or even entirely new, laboratory equipment and by vastly expanded computer power, which has made possible the development of greatly refined atomic structure codes. Thus in recent years, atomic data have not only become more accurate, but the body of data has also greatly increased, highly ionized species and complex heavy atoms have been addressed, fully relativistic treatments have been developed, and new energy and frequency ranges have been explored. This special issue focuses on many of these new sophisticated theoretical and experimental approaches that have made high precision atomic physics a reality. On the experimental side, several contributions cover the area of highly charged ions, where accurate measurements have become possible mainly due to the availability of electron beam ion traps (EBITs) and the utilization of storage rings. Studies of QED effects in Li-like ions, determinations of atomic lifetimes and precision wavelength measurements of highly charged ions are discussed. Furthermore, two contributions illustrate the extremely high precision of spectroscopic measurements for heavy ions and atoms, and two fundamental investigations address a new search for the electric dipole moment of the electron and measurements of the anapole moment in Fr and Rb. On the theoretical side, the contributions demonstrate that new, expanded and refined atomic structure and electron-impact collision codes are successfully applied to complex atomic systems, such as highly charged ions and heavy atoms, using increasingly full relativistic treatments.

Calculations of the Stark broadening of hydrogen lines treat the radiating atoms and the perturbing ions as quasistatic. The present experiment represents an attempt to determine whether the possible breakdown of this approximation near the center of the line can account, at least partially, for the existing discrepancies between theoretical and experimental profiles in the core of the Balmer lines. The central regions of ${H}_{\ensuremath{\alpha}}$, ${H}_{\ensuremath{\beta}}$, ${H}_{\ensuremath{\gamma}}$, and ${H}_{\ensuremath{\delta}}$ profiles have been measured in a wall-stabilized arc over a range of atom-ion relative velocities by varying the atom-ion reduced mass. The cores of all four lines exhibit a significant dependence on the reduced mass. With increasing reduced mass, the experimental profiles gradually show more structure, but still less than the theories predict. Extrapolation of the results for ${H}_{\ensuremath{\alpha}}$ and ${H}_{\ensuremath{\beta}}$ to infinite reduced mass, i.e., to the static case, gives results that agree quite well with recent calculations.

We have measured the profiles of plasma-broadened and slightly red- or blue-shifted spectral lines of neutral argon and nitrogen in a wall-stabilized arc and have performed a detailed line-shape analysis with a computerized data acquisition and processing system. According to Stark broadening theory, isolated lines of neutral atoms in dense plasmas are mostly broadened by electron impact resulting in symmetrical Lorentzian profiles, and are also broadened by the plasma ions, which produce a small additional contribution to the width as well as asymmetries in the line profile. As in two earlier experimental studies, we have utilized this difference in symmetries to study the effects of ion broadening. In this paper we have extended our work to some unusual cases where lines exhibit relatively rare ``blue'' shifts and where we study spectral transitions which are appreciably broadened because they originate from high-lying atomic levels. Our results are again in close agreement with the quasistatic theory of ion broadening which predicts that the asymmetry pattern has a characteristic minimum and maximum near the central part of the lines, but this pattern is reversed for the blue-shifted lines. We have also utilized the asymmetries for a check on plasma homogene- ity. By deliberately including nonhomogeneous areas of emission into the line of sight, we found drastic, readily observable distortions in the asymmetry patterns.

A systematic study of the influence of cascades on heavy-ion beam-foil decay curves has been made. Using theoretical data for the lifetimes and initial populations of excited states, decay curves simulating beam-foil excitation conditions have been constructed for the resonance transition of three ions in the copper isoelectronic sequence. Various models for the initial population distribution were tested by comparison with a detailed beam-foil decay curve available for Krviii. We found that customary exponential-fitting methods were not able to extract the primary lifetimes from the simulated curves used in constructing them, although the replenishment ratios were close to zero. General implications of this subtle masking of the primary lifetime by numerous cascades for the accuracy of experimental beam-foil data are discussed, especially for $\ensuremath{\Delta}n=0$ transitions in heavy ions.

Wavelengths, energy levels, level classifications, oscillator strengths, and radiative transition probabilities for the nickel ions Ni IX to Ni XXVIII are critically reviewed and tabulated. Grotrian diagrams are also presented to provide graphical overviews. The literature has been surveyed to mid-1986.

Based on comparisons with recent theoretical data, it is shown that the effective Gaunt factor for Δn = 0 transitions in alkali-like ions is within 25% of unity in most cases and is a slowly varying function of energy. A more complex energy dependence is noted for some non-alkali-like spectra, and especially for Δn ≠ 0 excitations. A method for the approximation of important correlation effects in the target is discussed for transitions of the type ns21S-nsnp 1P0.

We have measured the profiles of plasma-broadened, slightly red-shifted spectral lines of neutral argon with a wall-stabilized arc and performed a detailed line-shape analysis with a computerized data acquisition and processing system. According to Stark broadening theory, isolated lines of neutral atoms in dense plasmas are broadened mostly by electron impact, which results in symmetric Lorentzian profiles. An additional small broadening contribution, which is asymmetric in nature, is due to the plasma ions. This difference in symmetries provides the possibility of separating ion broadening effects from the electron broadening. In full agreement with the quasistatic theory of ion broadening, our experiment shows asymmetry patterns with characteristic minima and maxima near the central part of the lines. While the positions of these extrema---as well as the zero crossing point---stay essentially constant for all lines when compared on a reduced wavelength scale, the amplitudes of the extrema vary from line to line. Measurements of the amplitudes thus allow, by comparison with theoretical asymmetry patterns, the determination of ion broadening parameters.

We have measured detailed profiles of plasma-broadened neutral-carbon lines, utilizing a wall-stabilized arc source and a specially designed data acquisition and processing system. We analyzed the lines in terms of symmetric Lorentzian profiles in order to isolate the deviations due to asymmetries and found regular patterns of an antisymmetric nature around the line centers. The asymmetry patterns have a common shape with a minimum, maximum, and zero crossing at the same points on a reduced wavelength scale, but they vary widely in their amplitudes. These findings are in excellent qualitative agreement with the quasistatic theory of ion broadening due to the quadratic Stark effect. A comparison and match of experimental and theoretical amplitudes has thus been used to determine the ion broadening parameters of these lines, which are in satisfactory agreement with directly calculated values.

Wavelengths for about 47,000 spectral lines of atoms and atomic ions, as well as transition probabilities A for about 5000 lines, are tabulated. The data were selected in such a way as to include the prominent lines over a wide spectral region. Part I contains wavelengths of lines of neutral through quadruply ionized atoms in the range 40 to 40,000 A. This information is presented in two different ways: (1)separate line lists grouped according to chemical element and further subdivided according to stage of ionization; and (2) a general table of wavelengths ordered numerically, with relative intensity, chemical element, and stage of ionization indicated for each line. Part II contains transition probability data for atoms in various stages of ionization, with emphasis on the neutral and singly ionized species. This table is arranged according to the chemical element and is further subdivided according to stage of ionization. Estimates of the accuracies of the A-values are provided. Wavelengths, energy levels, and statistical weights serve to identify the lines and to provide useful data for plasma spectroscopy applications. (Author)

The VUV spectrum of foil-excited fast Zn ions has been studied in search for the intercombination transitions in Mg I-, Al I- and Si I-like ions. The line identifications are supported by decay curve measurements. The wavelength and lifetime data are compared with available theoretical predictions.

The plasma red shifts of H/sub ..cap alpha../ and D/sub ..cap alpha../ were measured in an atmospheric-pressure wall-stabilized arc, which was operated in argon with a small admixture of either hydrogen or deuterium. The measurements have yielded, within the experimental uncertainties, the same red shifts for H/sub ..cap alpha../ and D/sub ..cap alpha../, i.e., zero mass dependence.