A pathway to ultracold bosonic 23Na39K ground state molecules

We spectroscopically investigate a pathway for the conversion of (NaK)-Na-23-K-39 Feshbach molecules into rovibronic ground state molecules via stimulated Raman adiabatic passage. Using photoassociation spectroscopy from the diatomic scattering threshold in the a(3)Sigma(+) potential, we locate the resonantly mixed electronically excited intermediate states vertical bar B-1 Pi, v = 8 > and vertical bar c(3)Sigma(+), v = 30 > which, due to their singlet-triplet admixture, serve as an ideal bridge between predominantly a(3)Sigma(+) Feshbach molecules and pure X-1 Sigma(+) ground state molecules. We investigate their hyperfine structure and present a simple model to determine the singlet-triplet coupling of these states. Using Autler-Townes spectroscopy, we locate the rovibronic ground state of the (NaK)-Na-23-K-39 molecule (|X-1 Sigma(+), v = 0, N = 0 >) and the second rotationally excited stateN.=. 2 to unambiguously identify the ground state. Wealso extract the effective transition dipole moment from the excited to the ground state. Our investigations result in a fully characterized scheme for the creation of ultracold bosonic (NaK)-Na-23-K-39 ground state molecules.