Two-photon photoassociation spectroscopy of CsYb: Ground-state interaction potential and interspecies scattering lengths

( )We perform two-photon photoassociation spectroscopy of the heteronuclear CsYb molecule to measure the binding energies of near-threshold vibrational levels of the X-2 Sigma(+)(1/2) molecular ground state. We report results for (CsYb)-Cs-133-Yb-170, (CsYb)-Cs-133-Yb-173, and (CsYb)-Cs-133-Yb-174, in each case determining the energy of several vibrational levels including the least-bound state. We fit an interaction potential based on electronic structure calculations to the binding energies for all three isotopologs and find that the ground-state potential supports 77 vibrational levels. We use the fitted potential to predict the interspecies s-wave scattering lengths for all seven Cs+Yb isotopic mixtures.