2011MNRAS.412.1823M

Radiative lifetimes of 17 excited levels of Nb I, in the energy range 27 400-47 700/cm (5p y ⁶D°_9/2, 5px⁶D°_7/2, 5p w ⁴G°_7/2,9/2,11/2, 5s5p v ⁴D°_{1/2,3/2,5/2,7/2}, 5s6p n ⁴D°_{1/2,3/2,5/2,7/2}, 5s6p o ⁴F°_{3/2,5/2,7/2,9/2}), have been measured. For 15 of these levels, the lifetimes are obtained for the first time. The lifetimes were measured using the time-resolved laser-induced fluorescence technique and the experiments are complemented by a theoretical investigation using a relativistic Hartree-Fock method including core polarization. By combining the experimental lifetimes and the calculated branching fractions, we obtain transition probabilities for the individual de-excitation channels from the investigated levels.