Systematic investigations of the hyperfine structure constants of niobium I levels. Part I: Constants of upper odd parity energy levels between 16,672 and 31,025 cm−1 and discovery of a new level

In the wavelength region between 5540 and 6570 Å systematic laser spectroscopic studies of the hyperfine (hf) structure of Niobium I - lines were performed, detecting laser-induced fluorescence signals. Possible transition wavelengths were calculated as combinations between all known energy levels. Altogether about 380 transitions could be successfully excited and their hyperfine structure could be investigated. This large manifold of lines allowed us to evaluate our results via multiple transitions between the system of upper and lower energy levels. In Part I we report on transitions between lower even parity levels between 0 and 13,515 cm-1 and upper odd parity levels between 16,672 and 31,025 cm−1. Most of the hyperfine structure constants of the involved levels could be determined with lower uncertainty compared to literature values. The discovery of a previously unknown energy level, 27,994.38 cm−1, odd parity, J = 1/2, is also reported.