Hyperfine structure investigations of Mn I - Part I: Experimental and theoretical studies of the hyperfine structure in the even configurations

Optogalvanic laser spectroscopy has been applied to measure the hyperfine structure of 12 spectral lines of Mn I in the wavelength regions of 660-645 nm and 933-911 nm. Experimental hyperfine structure constants A and B of the isotope ⁵⁵ Mn have been determined for seven levels of even and seven levels of odd parity. Additionally, a parametric analysis of the fine structure and the magnetic dipole hyperfine structure has been performed for the three even configurations 3d⁵4s², 3d⁶4s and 3d⁷. Very large values for the ratio a_3d¹⁰/a_3d⁰¹ are found. Theoretical predictions for the magnetic dipole hyperfine structure constants A for all levels of the configurations 3d⁵4s², 3d⁵4s and 3d⁷ are given.