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

Abstract

We perform two-photon photoassociation spectroscopy of the heteronuclear CsYb molecule to measure the binding energies of near-threshold vibrational levels of the $X{\phantom{\rule{3.33333pt}{0ex}}}^{2}{\mathrm{\ensuremath{\Sigma}}}_{1/2}^{+}$ molecular ground state. We report results for $^{133}\mathrm{Cs}^{170}\mathrm{Yb}$, $^{133}\mathrm{Cs}^{173}\mathrm{Yb}$, and $^{133}\mathrm{Cs}^{174}\mathrm{Yb}$, 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.