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

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 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 Π 1/2 and 2 Π 3/2 states, but lead consistently and unambiguously to deviations from experimental-based adiabatic transition energy estimates for the 2 Σ 1/2 excited electronic state and show that more measurements are needed to clarify spectroscopic assignment of the 2 ∆ states.