Photoassociative creation of ultracold heteronuclear 6Li40K* molecules

We investigate the formation of weakly bound, electronically excited, heteronuclear (LiK)-Li-6-K-40* molecules by single-photon photoassociation in a magneto-optical trap. We performed trap loss spectroscopy within a range of 325 GHz below the Li(2S(1/2)) + K(4P(3/2)) and Li(2S(1/2)) + K(4P(1/2)) asymptotic states and observed more than 60 resonances, which we identify as rovibrational levels of 7 of 8 attractive long-range molecular potentials. The long-range dispersion coefficients and rotational constants are derived. We find large molecule formation rates of up to similar to 3.5 x 10(7) s(-1), which are shown to be comparable to those for homonuclear K-40(2)*. Using a theoretical model we infer decay rates to the deeply bound electronic ground-state vibrational level X-1 Sigma(+)(v' = 3) of similar to 5 x 10(4) s(-1). Our results pave the way for the production of ultracold bosonic ground-state (LiK)-Li-6-K-40 molecules which exhibit a large intrinsic permanent electric dipole moment. Copyright (C) EPLA, 2011