Theoretical investigation of laser cooling for BN- anion by ab inito calculation

Spectroscopy and rovibrational cooling of AuF and its cation

The feasibility of laser cooling of AuF molecule and its cation are investigated from vibrational and rotational perspectives. The spectroscopy of AuF molecule and AuF⁺ molecular cation are obtained by the method of multireference configuration interaction plus Davidson correction (MRCI + Q) and spin-orbit coupling (SOC) effect. On account of the accurate molecular spectroscopy and the transition dipole moment, the Franck-Condon factors and radiative lifetimes of AuF molecule and AuF⁺ molecular cation are calculated. Comparing the criterias of laser cooling candidate molecules, the AuF is an excellent candidate for laser cooling and while AuF⁺ is not sutable. The b³Π₀₊ ↔ Χ¹Σ⁺₀₊ transition of AuF is selected for laser cooling and an optical cycling scheme is proposed. The scheme possesses highly diagonally Franck-Condon factors and the scattered photons achieve ∼ 10⁴. Furthermore, the rotational transition analysis is also included in our work and found that its Franck Condon factors and Einstein coefficients are undistorted. Our work could provide theoretical support and accelerate the laser cooling of AuF molecules in experiments.