Laser Spectroscopy of Rydberg Level Hyperfine Structure Investigations in Niobium I

We have applied high-resolution laser spectroscopic techniques to measure the hyperfine structure of the high-lying levels of atomic niobium: 20 well-resolved spectra were measured using Doppler-limited optogalvanic spectroscopy technique and 10 spectra using Doppler-reduced saturation absorption spectroscopy technique in the wavelength range between 645~nm and 675~nm. We have precisely determined the magnetic dipole hyperfine structure constants $A$ for 42 levels and electric quadrupole hyperfine structure constants $B$ of 15 levels. 17 $A$ constants and 5 $B$ constants were measured for the first time. With the present work the experimental hyperfine data for the levels of odd parity of atomic Nb is extended.