Abstract. The isotope shift and hyperfine structure in a rhenium hollow cathode discharge was studied for transitions of the type 5d56s7s-~5d56s6p and 5d56s6d 5 d 5 6 s 6p through Doppler-free saturation absorption laserspectroscopy and high resolution interferometry. Taking configuration mixing in the lower levels of 5d 5 6s 6p under consideration, we obtain average configuration isotope shift values for 5d56s7s of -1760(100) MHz and for 5d 5 6s 6d of -1930(200) MHz. These experimental values compare extremely well with the theoretically predicted configuration isotope shifts in rhenium, based on pseudo-relativistic Hartree-Fock calculations, of -1710 MHz and -I940 MHz, resp. In addition hyperfine structure constants for rhenium levels of 5 d 5 6 s 6 d are reported here for the first time.

Optogalvanic laser spectroscopy has been applied to measure the hyperfine structure of 12 spectral lines of Mn I in the wavelength regions of 660–645 nm and 933–911 nm. Experimental hyperfine structure constants A and B of the isotope 55Mn have been determined for seven levels of even and seven levels of odd parity. Additionally, a parametric analysis of the fine structure and the magnetic dipole hyperfine structure has been performed for the three even configurations 3d54s2, 3d64s and 3d7. Very large values for the ratio a3d10/a3d01 are found. Theoretical predictions for the magnetic dipole hyperfine structure constants A for all levels of the configurations 3d54s2, 3d64s and 3d7 are given.

Optogalvanic laser spectroscopy has been applied to measure the hyperfine structure of 19 spectral lines of La I in the wavelength regions from 570 to 590 nm and 700 to 825 nm. Experimental hyperfine structure constants A and B of the isotope139La have been measured for 16 levels of odd parity. From those values six magnetic dipole and ten electric quadrupole constants have been determined for the first time. Some disagreements with previously obtained values are discussed.

No abstract

High-resolution laser spectroscopy techniques have been applied in the wavelength range between 645 and 675 nm to measure the hyperfine structure (hfs) of high-lying levels of atomic niobium. Using Doppler-limited optogalvanic spectroscopy 20 well-resolved spectra were measured and 10 spectra using Doppler-reduced saturation absorption spectroscopy technique. We have precisely determined the magnetic dipole hfs constants A of 42 levels and electric quadrupole hfs constants B of 15 levels. For the first time 17 A constants and 5 B constants were measured.