Photoassociative creation of ultracold heteronuclear ⁶Li⁴⁰K^* molecules

¹ Laboratoire Kastler Brossel, École Normale Supérieure, CNRS, Université Pierre et Marie-Curie 24 rue Lhomond, F-75231 Paris Cedex 05, France, EU
² Laboratoire Aimé Cotton, CNRS, Université Paris-Sud 11 - F-91405 Orsay, France, EU

^a armin.ridinger@gmail.com

Received: 2 August 2011
Accepted: 7 September 2011

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(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 ∼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.