High-resolution laser spectroscopy of the hyperfine structure of high-lying levels of Nb i

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.