Isotope shift measurements were performed on 33 transitions of Ne i by means of optogalvanic and intermodulated optogalvanic spectroscopy as well as saturation absorption spectroscopy. Using a large number of line isotope shift values obtained from both literature and our measurements, the level isotope shifts were calculated with improved concistency. Fine structure calculations were performed in odd configurations in order to obtain isotope shift parameters by means of the parametric method, 2p 5 3s: g 1 = −1077.5 (7), z 2p = 15.3(3), 2p 5 5s: g 1 = −104(26), z 2p = 14(6), 2p 5 4d: g 1 = −42(6), z 2p = 17(3).
Aims. The aim of this work is to increase the amount of hyperfine structure data of atomic niobium (Nb I), which is needed for astrophysicists for the detailed analysis of new stellar spectra. Particular emphasis was placed on the investigation of energy levels with unknown hyperfine structure constants. Methods. The hyperfine structure in the spectrum of Nb I was studied using laser-induced fluorescence spectroscopy and laser optogalvanic spectroscopy with a tuneable single-mode cw Ti:Sa laser in the wavelength range from 750 nm to 865 nm. The Nb atoms were produced and excited in a liquid-nitrogen-cooled hollow-cathode plasma. Results. We measured and analysed 81 spectral lines, 19 of which are not previously known from the literature. In total, the magnetic dipole hyperfine structure constants A were determined for 28 energy levels of even and 53 energy levels of odd parity. The electric quadrupole hyperfine structure constants B were only determined in a few cases, when the spectra were clearly resolved and/or when a level was found from several transitions. The magnetic dipole hyperfine structure constants A of 13 even and 11 odd levels as well as the electric quadrupole hyperfine structure constants B of 13 even and 17 odd levels are presented for the first time. For the other levels, improved values of hyperfine structure constants are given. Conclusions. The hyperfine structure can have a significant effect on stellar absorption line profiles, and the corresponding abundances can be substantially overestimated if these effects are not taken into account. Therefore, a detailed consideration of the hyperfine structure is important for stellar abundance determinations. The present work substantially increases the knowledge of hyperfine structure of Nb, which plays an important role in investigating the nucleosynthesis of heavy elements.
Laser-induced fluorescence spectroscopy was applied in order to find new energy levels of the niobium atom. A continuous wave tuneable titanium–sapphire laser in the wavelength range from 750 to 865 nm and a hollow-cathode lamp were used. We discovered four energy levels of even parity, three lying levels below 19 000 cm−1 and one at much higher energy. Additionally hyperfine structure data of six levels of odd parity were determined.
The spectrum of atomic vanadium was recorded using high-resolution Fourier transform spectroscopy with optical bandpass filters in the wavelength range from 360 to 500 nm. Vanadium atoms are produced and excited in a hollow-cathode discharge. The main focus lies on the determination of the magnetic dipole hyperfine constants A of the lowest multiplet of odd parity, the 6 G of the configuration 3d 3 4s4p, the hyperfine structure (HFS) of which was unknown to date. The HFS of the lines, connecting this multiplet with the multiplets 3d 3 4s5s 6 F, 3d 3 4s4d 6 H and 3d 3 4s4d 6 G, was observed and analysed. New results are presented for all six levels belonging to 3d 3 4s4p 6 G as well as for seven high-lying levels belonging to 3d 3 4s4d 6 H and 3d 3 4s4d 6 G. The experimental results for the lowest multiplet of odd parity are compared with calculated magnetic dipole hyperfine constants which were estimated using the effective-operator formalism in the pure LS coupling case.
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