Revised level energies of Nb I

With the use of wave number calibrated Fourier transform spectra spanning from the IR to the UV wavelength range, the values of energy levels of the atomic niobium (Nb I) have been revised. Due to recently published work (JQSRT 332 (2024) 109285) now the magnetic dipole hyperfine structure constants are available for all known Nb I levels. This allows to find the center of gravity wave numbers of the observed spectral lines with high accuracy. Revised level energies of all 399 known fine structure levels are determined using a global fit of altogether 1756 spectral lines, based on a least squares procedure. A comparison between our new results and available literature values is given and discussed.