High resolution photoassociation spectroscopy of the excited c^{3}Σ_{1}^{+} potential of ^{23}Na^{133}Cs

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.