Accurate \textit{ab initio} calculations of RaF electronic structure indicate the need for more laser-spectroscopical measurements

TL;DR

This paper presents high-accuracy ab initio calculations of the RaF molecule's electronic structure, highlighting discrepancies with experimental data and emphasizing the need for further laser spectroscopic measurements to clarify its electronic states.

Contribution

The study provides the first high-precision theoretical analysis of RaF's electronic states, comparing two methods and identifying specific states requiring further experimental investigation.

Findings

Excellent agreement with experimental excitation energies for certain states.

Identified deviations from experimental estimates for the $^2\Sigma_{1/2}$ state.

Highlighted the need for additional spectroscopic measurements for state clarification.

Abstract

Recently a breakthrough has been achieved in laser-spectroscopic studies of short-lived radioactive compounds with the first measurements of the radium monofluoride molecule (RaF) UV/vis spectra. We report results from high accuracy \emph{ab initio} calculations of the RaF electronic structure for ground and low-lying excited electronic states. Two different methods agree excellently with experimental excitation energies from the electronic ground state to the $^2\Pi_{1/2}$ and $^2\Pi_{3/2}$ states, but lead consistently and unambiguously to deviations from experimental-based adiabatic transition energy estimates for the $^2\Sigma_{1/2}$ excited electronic state and show that more measurements are needed to clarify spectroscopic assignment of the $^2\Delta$ states.