Spectroscopy and laser cooling of SiBr⁺: A computational perspective

In the previous work, the SiBr⁺ cation is suggested as a candidate molecule for laser cooling, and in this work, on the basis of high-level ab initio calculation, the possibility of SiBr⁺ cation laser cooling is studied by considering the core-valence electrons correlations and spin-orbit coupling (SOC) effect. The potential energy curves of 12 Λ-S states and 36 Ω states considering SOC were obtained by using the multi-reference configuration interaction method and Davidson correction. Our computed results show that the Franck-Condon factor f₀₀ for SiBr⁺ is only 0.619, which cannot guarantee that the number of the leaked photons is enough small, and more pumping laser beams are needed. Based on the calculated molecular properties, we discuss in detail the feasibility of laser cooling of SiBr⁺ and the results indicate that it is a challenge for laser cooling of SiBr⁺ .