Production and detection of ultracold LiRb molecules

We report on photoassociation (PA) of ultracold $^{7}$Li and $^{85}$Rb atoms and the production of ultracold heteronuclear $^{7}$Li$^{85}$Rb molecules in the electronic excited and ground states. The PA resonances are detected either using trap loss spectroscopy or by Resonance Enhanced Multi Photon Iononization (REMPI) of the ground-state LiRb molecules formed by spontaneous decay of the photoassociated excited state molecules. We identify several strong PA resonances below the Li (2s $^{2}$S$_{1/2}) + $ Rb (5p $^{2}$P$_{1/2})$ and the Li (2s $^{2}$S$_{1/2}) + $ Rb (5p $^{2}$P$_{3/2})$ asymptotes and experimentally determine the long range C$_{6}$ dispersion coefficients. We find an excited-state molecule formation rate of 3.5x10$^{7}$ s$^{-1}$ and a PA rate coefficient of 1.3x10$^{-10}$ cm$^{3}$/s, the highest among heteronuclear bi-alkali molecules. At large PA laser intensity, we observe the saturation of the PA rate coefficient close to the theoretical value at the unitarity limit. We will also present results on two-photon PA in LiRb.