Excitation of $^6S^\circ$, $^6P^\circ$, and $^6D^\circ$ levels of niobium atom by electron impact

The excitation of odd sextet levels of the niobium atom in collisions with slow electrons is investigated experimentally. The measured values of the excitation cross sections of the spectral lines of $\mathrm{NbI}$ are used to determine the excitation cross sections of energy levels. The available reference data on the branching factors are used for more complete inclusion of branching. The obtained values of excitation cross sections of the levels of the niobium atom are compared with the theoretical values.