Alexander Kramida

The program LOPT for least-squares optimization of energy levels

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.

Spectral Data for Gallium: Ga I through Ga XXXI

The energy levels and spectral lines of gallium atom in all stages of ionization have been compiled. Experimental data on spectral lines and energy levels exist for spectra Ga I through Ga VII, Ga XIII through Ga XXVI, and Ga XXX. For Li-like Ga XXIX through H-like Ga XXXI, theoretical data on energy levels and line wavelengths are compiled. For Ga I, Ga II, and Ga III we include radiative probabilities of electric-dipole transitions where available. For Ga XV through Ga XX, Ga XXIII through Ga XXVI, and Ga XXX, radiative probabilities of magnetic-dipole and electric-quadrupole transitions are included. The ground state configuration and term and a value of ionization energy are included for each ion.

A Critical Compilation of Energy Levels, Spectral Lines, and Transition Probabilities of Singly Ionized Silver, Ag II.

All available experimental measurements of the spectrum of the Ag+ ion are critically reviewed. Systematic shifts are removed from the measured wavelengths. The compiled list of critically evaluated wavelengths is used to derive a comprehensive list of energy levels with well-defined uncertainties. Eigenvector compositions and level designations are found in two alternate coupling schemes. Some of the older work is found to be incorrect. A revised value of the ionization energy, 173283(7) cm−1, equivalent to 21.4844(8) eV, is derived from the new energy levels. A set of critically evaluated transition probabilities is given.

Critical Evaluation of Data on Atomic Energy Levels, Wavelengths, and Transition Probabilities

Abstract Current methods of critical evaluation of wavelengths, energy levels, and transition probabilities for atoms and atomic ions at the National Institute of Standards and Technology are summarized.

Assessing Uncertainties of Theoretical Atomic Transition Probabilities with Monte Carlo Random Trials

This paper suggests a method of evaluation of uncertainties in calculated transition probabilities by randomly varying parameters of an atomic code and comparing the results. A control code has been written to randomly vary the input parameters with a normal statistical distribution around initial values with a certain standard deviation. For this particular implementation, Cowan’s suite of atomic codes (R.D. Cowan, The Theory of Atomic Structure and Spectra, Berkeley, CA: University of California Press, 1981) was used to calculate radiative rates of magnetic-dipole and electric-quadrupole transitions within the ground configuration of titanium-like iron, Fe V. The Slater parameters used in the calculations were adjusted to fit experimental energy levels with Cowan’s least-squares fitting program, RCE. The standard deviations of the fitted parameters were used as input of the control code providing the distribution widths of random trials for these parameters. Propagation of errors through the matrix diagonalization and summation of basis state expansions leads to significant variations in the resulting transition rates. These variations vastly differ in their magnitude for different transitions, depending on their sensitivity to errors in parameters. With this method, the rate uncertainty can be individually assessed for each calculated transition.

Critically Evaluated Energy Levels and Spectral Lines of Singly Ionized Indium (In II).

A comprehensive list of the best measured wavelengths in the In II spectrum has been compiled. Uncertainties of the wavelength measurements have been analyzed, and existing inconsistencies have been resolved. An optimized set of fine-structure energy levels that fits all observed wavelengths has been derived. Uncertainties of the energy level values have been reduced by an order of magnitude. An improved value of the ionization limit of In II has been determined by fitting quantum-defect and polarization formulas for several series of levels. Intensities of lines observed by different authors have been analyzed and converted to a uniform scale. A set of recommended values of radiative transition rates has been critically compiled, and uncertainties of these rates have been estimated. The hyperfine structure interval in the 5s 2S ground state of In III has been determined from the measurements of the 5sng and 5snh series in In II.

A critical compilation of energy levels and spectral lines of neutral boron

Observed spectral lines of neutral boron are critically compiled. From the selected best measurements, an improved and extended set of energy levels is derived for the two most abundant isotopes, 11B and 10B. The ionization energy is determined to a greater precision than previously given values. The connection between the quartet and doublet term systems is revised on the basis of an isoelectronic extrapolation.

Extended EUV and UV spectrum of Ne II

Spectra of Ne emitted by a Penning discharge were recorded in the extreme ultraviolet (EUV) on a 10.7m grazing-incidence spectrograph with phosphor image plates. The spectra provided 75 new lines of Ne II between 286 and 325A, from which 35 new energy levels of Ne II could be established. With these new levels, 86 unidentified lines from the NIST Pt‐Ne atlas (Sansonetti J E et al 1992 J. Res. Natl. Inst. Stand. Technol. 97 1) could be classified. The identifications of two existing levels of Ne II were revised.

Energy Levels and Spectral Lines of Singly Ionized Manganese (Mn II)

This compilation revises the previously recommended list of energy levels of singly ionized manganese (Mn II) and provides a comprehensive list of observed spectral lines and transition probabilities in this spectrum. The new level optimization takes into account critically assessed uncertainties of measured wavelengths and includes about a hundred high-precision wavelengths determined by laser spectroscopy and Fourier transform techniques. Uncertainties of 63% of energy levels and 74% of Ritz wavelengths are reduced by a factor of three on average.

Additions to the spectrum and energy levels and a critical compilation of singly-ionized boron, B II

We have undertaken the study of the Li-like spectrum of doubly ionized boron, B III. The spectroscopic data have been obtained with beam-foil spectroscopy and high-resolution spark spectroscopy. The experimental work was combined with theoretical calculations using ab initio and semi-empirical techniques. About 50 new transitions have been observed, and most of the previously known lines have been measured with improved accuracy. We have also critically evaluated all previous and recent data for this spectrum. Complete data on wavelengths and energy levels based on this analysis are tabulated.