Calculation of hyperfine structure in Tm II

TL;DR

This paper presents new theoretical calculations of hyperfine structure constants in singly ionized thulium, resolving previous discrepancies and aligning well with recent experimental data.

Contribution

It introduces a configuration interaction method with RPA corrections to accurately compute hyperfine constants in Tm II, improving upon prior theoretical approaches.

Findings

Good agreement with recent experimental measurements

Reliable predictions for unmeasured states

Addresses previous discrepancies in hyperfine data

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 40, 252 (1989)]. More recent measurements [Kebapc{\i} et al., ApJ 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.