Transition Dipole Moment Measurements of Ultracold Photoassociated85Rb133Cs Molecules by Depletion Spectroscopy**Supported by the National Key Research and Development Program of China under Grant No 2017YFA0304203, the National Natural Science Foundation of China under Grant Nos 61675120 and 11434007, the National Natural Science Foundation of China for Excellent Research Team under Grant No 61121064, the Shanxi Scholarship Council of China, the

Abstract

The transition dipole moments (TDMs) of ultracold 85Rb133Cs molecules between the lowest vibrational ground level, X1Σ+ (v = 0, J = 1), and the two excited rovibrational levels, 23Π0+ (v′ = 10, J′ = 2) and 21Π1 (v′ = 22, J′ = 2), are measured using depletion spectroscopy. The ground-state 85Rb133Cs molecules are formed from cold mixed component atoms via the 23Π0− (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)×10−3ea0 and 1.6(1)×10−2ea0, respectively, where ea0 represents the atomic unit of electric dipole moment. The enhance of TDM with nearly a factor of 5 for the 21Π1 (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.