Transition Dipole Moment Measurements of Ultracold Photoassociated ^85Rb^133Cs Molecules by Depletion Spectroscopy

The transition dipole moments (TDMs) of ultracold ^85Rb^133Cs molecules between the lowest vibrational ground level, X^1\it \Sigma^+ (v=0, J=1), and the two excited rovibrational levels, 2^3\it \Pi_0^+ (v'=10, J'=2) and 2^1\it \Pi_1 (v'=22, J'=2), are measured using depletion spectroscopy. The ground-state ^85Rb^133Cs molecules are formed from cold mixed component atoms via the 2^3\it \Pi_0^- (v=11, J=0) short-range level, then detected by time-of-flight mass spectrum. A home-made external-cavity diode laser is used as the depletion laser to couple the ground level and the two excited levels. Based on the depletion spectroscopy, the corresponding TDMs are then derived to be 3.5(2)\times10^-3ea_0 and 1.6(1)\times10^-2ea_0, respectively, where ea_0 represents the atomic unit of electric dipole moment. The enhance of TDM with nearly a factor of 5 for the 2^1\it \Pi_1 (v'=22, J'=2) excited level means that it has stronger coupling with the ground level. It is meaningful to find more levels with much more strong coupling strength by the represented depletion spectroscopy to realize direct stimulated Raman adiabatic passage transfer from scattering atomic states to deeply molecular states.