High resolution photoassociation spectroscopy of the excited c3 + 1 potential of 23Na133Cs

Abstract

We report on photoassociation spectroscopy probing the c 3 Σ + 1 potential of the bialkali NaCs molecule, identifying 11 vibrational lines between v ′ = 0 and v ′ = 25 of the excited c 3 Σ + 1 potential and fitting their rotational and hyperfine structure. The observed lines are assigned by fitting to an effective Hamiltonian model of the excited-state structure with rotational and hyperfine constants as free parameters. We discuss unexpected broadening of select vibrational lines and its possible link to strong spin-orbit coupling of the c 3 Σ + 1 potential with the nearby b 3 Π 1 and B 1 Π 1 manifolds. Finally, we report use of the v ′ = 22 line as an intermediate state for two-photon transfer of weakly bound Feshbach molecules to the rovibrational ground state of the X 1 Σ + manifold.