# Fine Structure Investigation and Laser Cooling Study of the CdBr Molecule

## TL;DR

This paper investigates the electronic structure and laser cooling potential of the CdBr molecule using advanced computational methods.

## Contribution

The study presents a detailed ab initio analysis of CdBr's electronic states and proposes a feasible laser cooling scheme.

## Key findings

- CdBr is identified as a promising candidate for direct laser cooling.
- A practical cooling scheme using four UV lasers is proposed with experimentally accessible parameters.
- Electronic and rovibrational properties are calculated, including transition dipole moments and radiative lifetimes.

## Abstract

The ab initio calculations of the electronic structure of the low-lying electronic states of the CdBr molecule are characterized in the 2S+1Λ(+/−) and Ω(+/−) representations using the complete active-space self-consistent field (CASSCF) method, followed by the multireference configuration interaction (MRCI) method with Davidson correction (+Q). The potential energy curves are investigated, and spectroscopic parameters (Te, Re, ωe, Be, αe, μe, and De) of the bound states are determined and analyzed. In addition, the rovibrational constants (Ev, Bv, Dv, Rmin, and Rmax) are reported for the investigated states with and without spin–orbit coupling. The electronic transition dipole moment curve (TDMC) is obtained for the C2Π1/2 − X2Σ+1/2 transition. Based on these data, Franck–Condon factors (FCFs), Einstein coefficient of spontaneous emission Aν’ν, radiative lifetime τ, vibrational branching ratios, and the associated slowing distance are evaluated. The results indicated that CdBr is a promising candidate for direct laser cooling, and a feasible cooling scheme employing four pumping and repumping lasers in the ultraviolet region with suitable experimentally accessible parameters is presented. These findings provide practical guidance for experimental spectroscopists exploring ultracold diatomic molecules and their applications.