Production of rovibronic ground state RbCs molecules via two-photon   cascade decay
  We report the production of ultracold RbCs molecules in the rovibronic ground state, i.e., $X^1\Sigma^+ (v=0, J=0)$, by short-range photoassociation to the $2^3\Pi_{0}$ state followed by spontaneous emission. We use narrowband depletion spectroscopy to probe the distribution of rotational levels formed in the $X ^1\Sigma^+(v=0)$ state. We conclude, based on selection rules, that the primary decay route to $X ^1\Sigma^+(v=0)$ is a two-step cascade decay that leads to as much as $33\%$ branching into the $J=0$ rotational level. The experimental simplicity of our scheme opens up the possibility of easier access to the study and manipulation of ultracold heteronuclear molecules in the rovibronic ground state. 
Toshihiko Shimasaki, Michael Bellos, C. D. Bruzewicz, Zack Lasner, and   David DeMille
physics.atom-ph