The Spectrum and Term Analysis of Singly Ionized Manganese

An extensive analysis of the Mn spectrum was carried out using high-resolution Fourier transform (FT) and grating spectroscopy of Mn–Ne and Mn–Ar hollow cathode discharge sources, over the range 82–5500 nm (1820–121,728 cm⁻¹). Spectral wavelengths for a total of 6019 Mn ii lines have been measured, of which 1345 are obtained through FT spectroscopy. These wavelengths are given to at least an order of magnitude lower uncertainty than previous measurements. These lines were used to identify 6256 Mn ii transitions and improve the values of 505 previously published energy levels with typical uncertainties of a few thousandths of a cm⁻¹, representing an order-of-magnitude reduction in uncertainty. We have verified and improved an additional 57 Mn ii energy levels, previously established through observation of stellar spectra alone, using our FT spectra. In addition, 52 new energy level values have been established. The number of classified lines reported is approximately 50% more than previously published. The new accurate data for 614 energy levels and 6019 lines will allow a more reliable analysis of Mn ii spectral lines in astrophysical spectra.