Laser Spectroscopic Investigation of the Hyperfine Structure of Atomic Manganese in the Mid-infrared Wavelength Range

The hyperfine structure of atomic manganese was studied with laser induced fluorescence spectroscopy and optogalvanic spectroscopy using a commercial hollow cathode discharge lamp and a fully automated single mode mid-infrared tunable laser diode system in the wavelength range from 1530~nm to 1610~nm. Five spectral lines has been analysed. Magnetic dipole hyperfine structure constants A for seven levels were determined by fitting the hyperfine structure using Voigt profile functions.

For two levels, the A constants were determined experimentally for the first time. For the other levels, the previously published hyperfine structure constants A could be confirmed and the accuracy of the values could be improved.

When comparing our two new experimental A-constants with calculated A-constants from the literature, which originate from a semi-empirical analysis of the odd parity levels in Mn, large deviations were found. Until now, experimental values were missing for a more precise calculation. Our new values offer the possibility for a future optimisation of the calculation.