Experimental study of the (4)0− short-range electronic state of the 85Rb133Cs molecule by high resolution photoassociation spectroscopy

•Ultracold 85RbCs molecules in (4)0− state are produced by PA and detected by RETPI.•More 6 resonances are presented, even with vibrational level down to v=2.•With the rotationally resolved PA spectra, rotational constants are determined.•Internuclear distance-dependent EDMs are compared with theoretical calculation.

We present the formation of ultracold 85Rb133Cs molecules in the (4)0− short-range electronic state and the measurement of the permanent electric dipole moment by high resolution photoassociation spectroscopy. With the rotationally resolved photoassociation spectra via resonance-enhanced two-photon ionization, spectral data have been extended to more vibrational levels compared to previous observations. Precise electric dipole moments are obtained by using the DC Stark effect of the photoassociation spectrum. These studies containing previously unobserved electronic states are important to understand the molecular structure and discover transition pathways for transferring ultracold atoms to deeply bound rovibrational levels of the electronic ground state.