Continuous Production of Rovibronic Ground State RbCs Molecules via Short-Range Photoassociation to the $B^{\mathrm{1}}\Pi $, $c^{\mathrm{3}}\Sigma^{\mathrm{+}}$, and $b^{\mathrm{3}}\Pi $ states

Electronic states with strong singlet-triplet mixing can be useful for efficient direct molecule production in the rovibronic ground state via short-range photoassociation (PA). We have observed rovibronic levels of the strongly mixed $B^{\mathrm{1}}\Pi (\Omega =$1), $c^{\mathrm{3}}\Sigma^{\mathrm{+}}(\Omega =0^{-}$ and 1), and $b^{\mathrm{3}}\Pi (\Omega =0^{-}$, 0$^{\mathrm{+}}$, and 1) states of $^{\mathrm{85}}$Rb$^{\mathrm{133}}$Cs in the energy range of 13950 -14200 cm$^{\mathrm{-1}}$ using short-range PA. For selected PA states, vibrational branching and rotational branching in the $X^{\mathrm{1}}\Sigma ^{\mathrm{+}}$ ($v=$0) state have been investigated using resonance-enhanced multiphoton ionization and depletion spectroscopy [1], respectively. Efficient production of the rovibronic ground state $X^{\mathrm{1}}\Sigma^{\mathrm{+}}(v=$0, $J=$0) has been observed for some of the PA states in this energy range. Molecule production rate up to $\sim $1$\times $10$^{\mathrm{4}}$ molecules /s into the rovibronic ground state has been achieved, which is a factor of 5 improvement compared to previously observed PA states [2]. [1] T. Shimasaki \textit{et al}., Phys. Rev. A \textbf{91}, 21401 (2015). [2] T. Shimasaki \textit{et al}., ChemPhysChem \textbf{17}, 3677 (2016).