High resolution photoassociation spectra of an ultracold Cs₂ long-range 0_u⁺ (6S_1/2+6P_1/2) state

In this paper, ultracold cesium molecules are formed through photoassociation technology, which is carried out in a magneto-optical trap. High resolution photoassociaion spectra with the rotational progressions up to J=7 are obtained. Three rovibrational levels of the long-range 0_u⁺ state of Cs₂ below the (6S_1/2+6P_1/2) dissociation limit are specifically investigated. By fitting their binding energy intervals to the non-rigid rotational model, the rotational constant of the long-range 0_u⁺ state is determined. A proportional dependence of the value of the rotational constant on the vibrational quantum number is demonstrated.