Photoassociative creation of ultracold heteronuclear 6Li40K* molecules

Abstract

We investigate the formation of weakly bound, electronically excited, heteronuclear 6Li40K* molecules by single-photon photoassociation in a magneto-optical trap. We performed trap loss spectroscopy within a range of 325 GHz below the Li(2S1/2)+K(4P3/2) and Li(2S1/2)+K(4P1/2) 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 ∼3.5×107s− 1, which are shown to be comparable to those for homonuclear 40K2*. Using a theoretical model we infer decay rates to the deeply bound electronic ground-state vibrational level X1Σ+(v′=3) of ∼5×104 s−1. Our results pave the way for the production of ultracold bosonic ground-state 6Li40K molecules which exhibit a large intrinsic permanent electric dipole moment.