Analyzing the photoassociation spectrum of ultracold ⁸⁵Rb ¹³³Cs molecule in (3)³⁺ state

We establish a theoretical model to analyze the photoassociative spectroscopy of Rb-85 Cs-133 molecules in the (3)(3)Sigma(+) state. The vibrational energy, spin-spin coupling constant, and hyperfine interaction constant of the (3)(3)Sigma(+) state are determined based on nine observed vibrational levels. Consequently, the Rydberg-Klein-Rees potential energy curve of the (3)(3)Sigma(+) state is obtained and compared with the ab initial potential energy curve. Our model can be adopted to analyze the photoassociative spectroscopy of other heteronuclear alkali-metal diatomic molecules in the (3)(3)Sigma(+) state.