Rovibrational Dynamics of RbCs on its Lowest ^1,3Σ⁺ Potential Curves Calculated by Coupled Cluster Method with All-Electron Basis Set

Relativistic ab initio potential curves of RbCs lowest ^1,3Σ⁺ states are calculated by diagonalizing the Douglas–Kroll–Hess Hamiltonian as implemented in Gaussian09 suite of programs. The ab initio calculations are performed at the CCSD­(T) level with UGBS1P+ basis set, a huge all-electron basis set. The rovibrational eigenenergies and eigenfunctions on the lowest ^1,3Σ⁺ ab initio potential curves are calculated by direct diagonalization of molecular Hamiltonian in a Fourier grid discrete variable representation. The results agree well with available experimental and theoretical work and the accuracy of theoretical descriptions of RbCs are increased, which is expected to be a good reference for further investigations

Experimental Determination of the Rotational Constants of High-Lying Vibrational Levels of Ultracold Cs₂ in the 0_g^– Purely Long-Range State

We report on a quantitative experimental determination of the rotational constants for the high-lying vibrational levels of the ultracold pure long-range Cesium molecules formed via photoassociation. The scheme relies on a precise reference of frequency difference in a double photoassociation spectroscopy, which is induced by two laser beams based on an acoustic-optical modulator. The rotational constants are obtained by fitting a nonrigid rotor model into the frequency intervals of the neighboring rotational levels deduced from the reference