Table 3:

Magnetic dipole hyperfine structure constants A in MHz for the levels of odd parity of Nb  I.

Notes. Level energies according to Humphreys & Meggers (1945); configurations and terms according to Kröger et al. (2007). The wavelength in air  given in the fourth column specifies the line, that was used to determine the hyperfine constant  ;  is the average result from eight measurements;  is the corresponding standard deviation. If more than one line was available for a level to determine  , the weighted mean value  is calculated, using  as weight. In column  the standard deviation, that resulted from the weighted mean value calculation is given as error. If known, reference values  from the literature are listed together with the indication of the method used. If more than one reference value has been published for a given level, only the most precise one is given.
^(a) Optogalvanic spectroscopy; ^(b) saturation absorption spectroscopy; ^(c) laser induced fluorescence spectroscopy; ^(d) laser radio-frequency double resonance.
^(*) FWHM and ratio between Gaussian and Lorentzian FWHM fixed during the fit; () error in sign in Basar et al. (2008); () is set equal to the uncertainty of the A_l-constant of the lower level.