IDEN2 - A program for visual identification of spectral lines and energy levels in optical spectra of atoms and simple molecules
Abstract The article describes a Java program that can be used in a user-friendly way to visually identify spectral lines observed in complex spectra with theoretically predicted transitions between atomic or molecular energy levels. The program arranges various information about spectral lines and energy levels in such a way that line identification and determination of positions of experimentally observed energy levels become much easier tasks that can be solved fast and efficiently. Program summary Program title: IDEN2 Program Files doi: http://dx.doi.org/10.17632/mwr2tk84sw.1 Licensing provisions: GPLv3 Programming language: Java v.1.8 Nature of problem: Line identification problem in atomic and molecular spectra that have a limited number of previously known low-excited energy levels and a large number of unidentified spectral lines (emission or absorption). The line identification consists of finding the lower and upper energy levels of transitions corresponding to each observed spectral line. Solution method: For each energy level (experimentally known or unknown), the list of observed spectral lines is displayed on a wavenumber scale as an image. This image is repeated with certain vertical shifts in several columns corresponding to other levels connected with the investigated one by theoretically predicted transitions. In each such column, the image of the line spectrum is shifted by the value corresponding to the energy of the connecting level. Then the problem of location of an unknown level is reduced to scrolling the screen until several spectral lines in different columns align along the same horizontal line. Various gadgets provide complete information about all pertinent entities, such as the level identities, wavelengths, observed and calculated intensities. Additional comments including restrictions and unusual features: A practical limitation on the size of the problem is imposed by the available RAM, which is typically sufficient to treat spectra with up to 100 000 spectral lines and 10 000 energy levels. The visual appearance of all gadgets, including font sizes, colors, and window sizes and positions, is completely customizable. An extensive Help system and User Guide are included.
The 4d75d configuration in the spectrum of six times ionized tin (Sn VII)
Abstract The spectrum of tin excited in a vacuum spark was observed with a 6.6-m normal incidence spectrograph. The 4d75p – 4d75d transitions in Sn VII were studied. 137 spectral lines of these transitions in the region 556 - 763 A were identified and 79 levels of the 4d75d configuration were found. Parametric calculations of the electric dipole transitions between the levels of the 4d8, 4p54d9, 4d75s, 4d76s, 4d75p and 4d75d configurations spanning the wavelength region from 153 A through 1250 A were performed.
Calculations of 5dN-16s systems using orthogonal operators: do orthogonal operators survive configuration interaction?
The merits and pitfalls of using orthogonal operators in systems with strong configuration interaction are illustrated by a study of a number of (5d+6s)N configurations (N=8, 9) ranging from Ir to Pb. Both the perturbational and the full diagonalization approach are applied. Criteria are given to indicate the regions where either operators based on perturbation theory or explicit configuration interactions are dominant. In both regions, orthogonal operators describe the (ground and) excited states well, provided they are extended by interconfiguration operators in the case of lower ionization, where full diagonalization of the three (5d+6s)N configurations is required. Ab initio calculations using second order perturbation theory show satisfactory agreement with the results from fits to experimental energy levels, except again for the lowest ionizations, where perturbation theory breaks down. It turns out to be a good approximation to exclude interactions treated by complete diagonalization from the perturbation expressions; both approaches can then be combined to describe excited state interactions.