Cold rubidium molecules formed in a magneto-optical trap

We report the first observation of translationally cold (90 microK) Rb2 molecules. They are produced in a magneto-optical trap in their triplet ground state. The detection is performed by selective mass spectroscopy after two-photon ionization into Rb2 +, resonantly enhanced through the intermediate molecular band. The two rubidium isotopes present very different types of behavior that are interpreted in terms of their respective collisional properties.