Laser cooling of copper monofluoride: a theoretical study including spin–orbit coupling†
Abstract
The feasibility of direct laser cooling of copper monofluoride (CuF) is investigated and assessed using ab initio methods with the inclusion of spin–orbit coupling (SOC) effects. Seven low-lying Λ–S states are calculated using an explicitly correlated multireference configuration interaction method with the Davidson correction (MRCI-F12 + Q). The spectroscopic properties of the Ω states are calculated, which are in very good agreement with the available experimental measurements and indicate that the influence of SOC effects is evident. We find that, the radiative lifetimes of transitions A(ν′ = 0) → a3Σ+1, b3Π1,0+ are much longer than that of the A(ν′ = 0) → X(ν = 0) transition; the vibrational branching ratios Rν′ν for the A(ν′) ← X(ν) transition are highly diagonally distributed with R00 being 0.991; and the evaluated transition wavelengths are located in the visible region. We further propose a laser cooling scheme based on the A(ν′) ← X(ν) transition, with which the laser cooling of CuF can be realized effectively. Moreover, a photoionization method is suggested for the magneto-optical trap detection of CuF.