Hyperfine structure measurements of Co I and Co II with Fourier transform spectroscopy.

2• The Fourier transform (FT) spectra were employed to extend the study of hyperfine structure (HFS) in Co I and Co II. 2• HFS constants A for 36 levels of Co I from 0.00 to 60,262.463 cm−1 were determined, of which 33 results are reported for the first time, as far as we know. Our study increased the total number of HFS constants A to over 333 for Co I. 2• HFS constants A for 61 levels of Co II from 11,651.277 to 85,876.271 cm−1 were determined, of which 58 results are reported for the first time, as far as we know. Our study increased the total number of HFS constants A to over 86 for Co II. We used some archival data from the Fourier transform spectrometer (FTS) at the US National Solar Observatory to study the hyperfine structure (HFS) patterns of Co I and Co II, and determined the HFS constants of Co I and Co II. In total, HFS constants A for 36 levels of Co I from 0.00 to 60,262.463 cm−1 and for 61 levels of Co II from 11,651.277 to 85,876.271 cm−1 were determined, of which 33 results for Co I and 58 results for Co II are reported for the first time, as far as we know. Our study increased the total number of HFS constants A to over 333 for Co I and over 86 for Co II. [ABSTRACT FROM AUTHOR]