Cold rubidium molecules formed in a magneto-optical trap

We report the first observation of translationally cold (similar to 90 mu K ) Rb-2 molecules. They are produced in a magneto-optical trap in their trip let ground state. The detection is performed by selective mass spectroscopy after two-photon ionization into Rb-2(+), resonantly enhanced through the intermediate a(3)Sigma(u)(+) --> 2(3)Pi(g) molecular band. The two rubidium isotopes present very different types of behavior that an interpreted in t erms of their respective collisional properties.