The determination of potential energy curve and dipole moment of the (5)0$^{\mathrm{+}}$ electronic state of $^{\mathrm{85}}$Rb$^{\mathrm{133}}$Cs molecule by high resolution photoassociation spectroscopy

The creation and manipulation of ultracold polar molecules have attracted intensive attentions due to their permanent electric dipole moments interacting strongly with an external electric field and with long-range dipole-dipole force, which facilitate applications such as precision measurement, quantum control of cold chemical reactions, and quantum computation. The (5)0$^{\mathrm{+}}$ state is a good candidate to produce ultracold ground state RbCs molecule through a short-range photoassociation (PA). We present the formation of ultracold $^{\mathrm{85}}$Rb$^{\mathrm{133}}$Cs molecules in the (5)0$^{\mathrm{+}}$ electronic state by PA and their detection via resonance-enhanced two-photon ionization. Up to v $=$ 47 vibrational levels including the lowest v $=$ 0 and lowest J $=$ 0 levels are identified with high resolution. Precise Dunham coefficients and the Rydberg-Klein-Rees potential energy curve of the (5)0$^{\mathrm{+}}$ state are determined The electric dipole moments with respect to the vibrational numbers of the (5)0$^{\mathrm{+}}$ electronic state are also measured in the range between 1.9 and 4.8 D. These comprehensive studies on previously unobserved rovibrational levels of the (5)0$^{\mathrm{+}}$ state are helpful to understand the molecular structure and discover suitable transition pathways for transferring to the lowest rovibrational level of the ground state.