Atomic Physics Division

The procedure of level optimization for the 198 Hg I spectrum emitted by electrodeless discharge lamps is revisited. Wavelength-measurement uncertainties and systematic shifts caused by interactions with the buffer gas and by calibration procedures are carefully analyzed and accounted for. Based on this extended analysis of the original measurements, the energy levels are re-optimized, which results in an improved set of level values consistent with the revised measured wavelengths. The newly obtained reliable Ritz wavelengths can be used as secondary wavelength standards in the wide range from 1200 Å to 65 000 Å.

CITATIONS 0 READS 11 2 authors: Some of the authors of this publication are also working on these related projects: Critical compilation and new measurements of energy levels and spectral lines of neutral carbon View project Critical compilation and new measurements on the spectrum of singly ionized copper View project

The energy levels and spectral lines of multiply ionized tungsten atoms, W 2+ through W 73+ , have been compiled. Experimental data on spectral lines and energy levels exist for the spectra of W III through W VII, W XXVIII through W LI, W LIII, and W LV through LXV. For W VIII, the four lowest energy levels were derived from the series limits of W VII. For W LXIV (Na-like) and W LVI (K-like), we supplement experimental data on energy levels and wavelengths with predicted values found by accurate interpolations and extrapolations along the isoelectronic sequences. For W LXXIII (He-like) and W LXXIV (H-like), theoretical data on energy levels and line wavelengths are compiled. For W III, we include experimentally determined radiative transition probabilities where available. The ground state configurations and terms were determined for all stages of ionization. A value of ionization energy is included for each ion.

The article describes a program that solves the least-squares optimization problem for finding the energy levels of a quantum-mechanical system based on a set of measured energy separations or wavelengths of transitions between those energy levels, as well as determining the Ritz wavelengths of transitions and their uncertainties. The energy levels are determined by solving the matrix equation of the problem, and the uncertainties of the Ritz wavenumbers are determined from the covariance matrix of the problem.

All experimental data on the valence-shell-excited and core-excited spectra of Li-like neon, including previously unpublished beam-foil spectroscopy data, have been compiled and critically evaluated. Seventeen spectral lines have been newly identified. Sets of recommended energy levels have been derived from the total list of observed lines and from selected results of theoretical and semi-empirical calculations. An accurate value of the ionization potential has been derived from existing theoretical calculations.

All observed spectral lines of Ne III in the range 204Å to 36 µm (277 cm −1 to 490000 cm −1 ) have been compiled and critically evaluated. 57 visible and ultraviolet lines of Ne III have been precisely measured using Fourier transform spectroscopy. An optimized level scheme has been derived from the total list of observed lines. Relative positions of about 180 out of a total of 226 previously known energy levels of Ne III have been determined with improved accuracy compared to previous studies. Excitation energies of almost all excited levels have been revised by (1.5-2.0) cm −1 . 127 precise wavelength standards in the region 210Å to 2900Å have been derived. Concepts of error current and covariance matrix have been implemented in a computational algorithm that permits one to derive the uncertainties of Ritz wavelength standards obtained from a set of least-squares-optimized energy levels. Nine new energy levels have been found, and 16 new transitions have been identified in the extreme ultraviolet region. The ionization potential has been increased by 4.5 cm −1 . The new value is (511543.5 ± 2.7) cm −1 (63.4233 eV ± 0.0003 eV).

Previous works devoted to the Ne V spectrum are very fragmentary and yield a rather controversial picture of this ion. A lot of unidentified lines are still reported in these multiple studies. In the present paper, Hartree-Fock calculations and least-squares fits over the whole set of the available data (including the most recent ones) have been performed. As a result, a comprehensive view of the Ne V spectrum is presented. 10 new energy levels and 40 newly classified lines are proposed. An improved value of the ionisation potential of Ne V is also proposed.

Spectra of neon-filled hollow cathode discharge lamps were observed by means of high-resolution Fourier-transform spectroscopy (FTS) covering the region from vacuum ultraviolet to near infrared. By combining these new measurements with results of other FTS and grating spectroscopy observations, we compiled a complete list of approximately 1700 spectral lines of Ne II covering the range from 324Å to 130000Å. All known energy levels of Ne II were derived from this line list with improved accuracy. The newly optimized energy levels were used to derive a set of Ritz wavelength standards in the vacuum ultraviolet that are in good agreement with the previously used data. An improved classification of energy levels was made with the help of parametric calculations, and the existing controversy in the naming of strongly mixed levels was resolved.

All experimental data on Ne VII, including previously unpublished beam-foil spectroscopy data, have been compiled and critically evaluated. More than a hundred spectral lines have been newly identified. For 40 transitions, the previous identifications have been revised. These revisions resolved all existing contradictions between previously published interpretations of the spectrum. An optimized level scheme has been derived from the total list of observed lines. About a hundred new energy levels have been found, including several highly excited hydrogenic levels. Based on these newly determined levels, as well as on the analysis of theoretical data, the ionization potential has been newly determined with improved confidence.

In this compilation we have used data from some 20 references, only two of which were available to C. E. Moore for her 1949 Atomic Energy Levels tables. The new compilation thus includes significant revisions, extensions, and improvements of the earlier data for configurations of the types 1s 2 2snl and 1s 2 2 pnl and also extends the energy range to higher configurations, including those involving 1s electron excitation. The observed wavelengths for some 200 lines are given with their energy-level classifications. The wavelength measurements, which extend from 89 to 31 780 Å, were obtained from emission spectra of hollow-cathode and arc discharges, beam-foil spectra, and far-ultraviolet photoabsorption spectra. In addition to the energy levels derived from these spectra, we include levels obtained from multiphoton resonance-ionization mass spectrometry and projectile-Auger spectroscopy. We have evaluated a number of levels by using series formulas and/or theoretical results; these levels are more accurate than values derived from available wavelength measurements. Wavelengths calculated from energy-level differences are given for all lines; these ''Ritz'' wavelengths are more accurate than the observed values wherever the differences are significant.

Energy levels, wavelengths, and transition probabilities of the first and second spectra of tungsten, W I and W II, have been compiled. Wavelengths of observed transitions and energy levels derived from those wavelengths have been obtained from a critical evaluation of the available literature. Measured transition probabilities for some of the observed transitions have been compiled from the published literature. © 2006 by the U.S. Secretary of Commerce on behalf of the United States. All rights reserved.

On the basis of all the available observations of the Ne VI spectrum, particularly the new beam-foil spectra obtained at Liège University, approximately 50 new line assignments are proposed and approximately 30 new energy levels are determined in Ne VI. All known energy levels have been improved, and a new value is proposed for the ionization potential. The new line identifications are supported by Hartree-Fock calculations combined with parametric fitting of energies and transition rates.