Calculation of hyperfine structure in Tm \textsc{ii}

Abstract

The first measurements of the magnetic dipole hyperfine structure constants A in singly ionized thulium revealed substantial discrepancies with the corresponding calculations [Mansour et al., NIMB \textbf{40}, 252 (1989)]. More recent measurements [Kebapcı et al., ApJ \textbf{970}, 23 (2024)] expanded very limited dataset of that work and demonstrated that two of the previously reported experimental A values were incorrect, motivating new theoretical calculations. In this work, we employ the configuration interaction method to calculate the A constants for several low-lying levels in Tm II, with the random-phase-approximation corrections also taken into account. Our results show good agreement with the new experimental data and provide reliable predictions for additional states where measurements are not yet available.