Measurements of the Hyperfine Structure of Atomic Energy Levels in Co ii

Abstract

Analysis of hyperfine structure constants of singly ionized cobalt (Co II) were performed on cobalt spectra measured by Fourier transform spectrometers in the region 3000–63,000 cm −1 (33333 – 1587 Å). Fits to over 700 spectral lines led to measurements of 292 magnetic dipole hyperfine interaction A constants, with values between −32.5 mK and 59.5 mK (1 mK = 0.001 cm −1 ). Uncertainties of 255 A constants were between ±0.4 mK and ±3.0 mK, the remaining 37 ranged up to ±7 mK. The electric quadrupole hyperfine interaction B constant could be estimated for only one energy level. The number of Co II levels with known A values has now increased tenfold, improving and enabling the wider, more reliable, and accurate application of Co II in astronomical chemical abundance analyses.