Systematic investigations of the hyperfine structure constants of niobium I levels. Part III: High lying even parity levels (37,410–43,420 cm−1) and discovery of a new level

Abstract

The present work is the third part of a systematic investigation of the hyperfine structure of atomic Niobium using laser induced fluorescence spectroscopy. As in the previous two parts, spectral lines in the wavelength region between 5540 and 6570 Å were investigated. In the present part we report on 31 transitions between lower odd parity levels and high-lying even parity levels between 37,410 and 43,420 cm−1. 15 of these 31 lines were already known emission lines, the transition wavelengths of the other 16 lines were calculated as combinations between known energy levels. The constants of the involved levels could be determined, in most cases, with lower uncertainty compared to literature values. For some levels we had to use also results from an analysis of Fourier-transform spectra. The discovery of a previously unknown energy level, 32,361.11 cm−1, even parity, J = 5/2, is also reported.