New energy levels of atomic niobium (Nb I) discovered by laser-spectroscopic investigations

We report the discovery of 9 previously unknown energy levels of the atomic niobium, all having even parity. Two levels have energies below 19,500 cm−1 and angular momentum J = 3/2, while the energies of the others are located between 39,700 and 43,420 cm−1. The levels were discovered by laser excitation of several unclassified spectral lines in the wavelength range between 554 nm and 650 nm and detection of laser-induced fluorescence with a monochromator.