The spectroscopic properties of the low-lying excited states and laser cooling scheme of SrBr molecule

The potential energy curves and the transition dipole moments for seven electronic states of SrBr molecule are obtained via the multi-reference configuration interaction method and the all-electron basis sets. The Davidson and relativistic corrections are also included. Based on the obtained potential energy curves, the rotational and vibrational energy levels of each electronic state are determined by solving the nuclear motion equation of the molecule. The spectroscopic parameters are fitted from the obtained energy levels by using Dunham expression. Moreover, the spin-orbit coupling splits of the A²Π state are considered to construct the optical laser cooling scheme. The Frank-Condon factors, radiation lifetimes, radiation widths between the ground electronic state and ²Π_{1/2, 3/2}/B²Σ⁺ states are calculated. Then, the feasibility of laser cooling is explored and the optical scheme is proposed. The results demonstrate that the SrBr molecule is a promising candidate for laser cooling.