Spectroscopic studies of the (4)^1\Sigma^+ state of RbCs and modeling of the optical cycle for ultracold X ^1\Sigma^+ (v=0,J=0) molecule production
V. Zuters, O. Docenko, M. Tamanis, R. Ferber, V. V. Meshkov, E. A. Pazyuk, and A. V. Stolyarov
Accepted
We performed high-resolution Fourier-transform spectroscopy measurements and direct-potential-fit of the shelflike RbCs (4)1S+ state. Overall 2317 rovibronic v,J term values with v [3,88], J [7,276] were obtained with accuracy 0.01 cm-1 from the (4)1S+ X1S+,a3S+ laser induced fluorescence (LIF) spectra. The mass-invariant potential energy curve constructed by means of the Chebyshev polynomial expansion reproduced the experimental term values of both 85Rb133Cs and 87Rb133Cs isotopologues with a standard deviation of 0.005 cm-1. We simulated the optical cycle X1S+,a3S+(v,J=0)(4)1S+(v,J=1)X1S+(v=0,J=0) appropriate to transfer translationally ultracold RbCs molecules into their absolute ground state from the weakly bound rovibronic levels of both singlet X1S+ and triplet a3S+ ground states. The optimal transfer via the intermediate (4)1S+ state with v=58,60, and 61 for 85Rb133Cs as well as v=59 and 61 for 87Rb133Cs was predicted. The required spin-allowed (4)1S+ - X1S+ and spin-forbidden (4)1S+-a3S+ dipole transition moments were obtained in the framework of ab initio quasi-relativistic calculations. The predicted (4)1S+ X1S+,a3S+ transition probabilities were consistent with the experimental relative intensity distributions for several (4)1S+(v) X,a(v) LIF progressions.