Revised energy levels and hyperfine structure constants of Ta II

The Role of the Hyperfine Structure for the Determination of Improved Level Energies of Ta II, Pr II and La II

“…[25]-by Stachowska et al [28] performing a semi-empirical analysis, which confirmed also the new high lying levels above 72,000 cm −1 (Figure 4). For this analysis, an important point was to exclude energy levels given in literature but in reality not existing.…”

“…Using the obtained vacuum wave numbers, a transition matrix was built up, and, in a global least squares fit, values for the level energies were calculated, together with their statistical uncertainties. The result was published recently [25].…”

“…One example of such spectra-in comparison with the FT spectra-is given in Ref. [25]. Another example where two spectral lines, one belonging to Ta I and the second to Ta II, are located side by side ( Figure 1).…”

New levels of Ta II with energies higher than 72,000 cm −1

“…In order to obtain such low uncertainty, it was necessary to also correct the energies of all known Ta II energy levels. This subject will be reported in detail in a forthcoming paper [20].…”

Finding of previously unknown energy levels using Fourier-transform and laser spectroscopy

“…Such energy levels are used in the classification program, presently for Ta I, La I and La II, Pr I. The energies of Pr II [19] and Ta II [20] levels were improved using a global fit program. For La II, the work on fitted level energies is in progress.…”