Observation of Feshbach-like resonances in collisions between ultracold molecules -: art. no. 123201

We observe magnetically tuned collision resonances for ultracold Cs(2) molecules stored in a CO(2)-laser trap. By magnetically levitating the molecules against gravity, we precisely measure their magnetic moment. We find an avoided level crossing which allows us to transfer the molecules into another state. In the new state, two Feshbach-like collision resonances show up as strong inelastic loss features. We interpret these resonances as being induced by Cs(4) bound states near the molecular scattering continuum. The tunability of the interactions between molecules opens up novel applications such as controlled chemical reactions and synthesis of ultracold complex molecules.