PHOTOASSOCIATION SPECTRUM OF ULTRACOLD RB ATOMS

We study the photoassociative collisional loss of laser-cooled Rb atoms from a far-off resonance optical dipole force atom trap. We obtain a well-resolved photoassociation spectrum from 50 cm-1 to 980 cm-1 below the first excited dissociation limit of the Rb2 molecule. Two vibrational series associated with excited Rb2 3SIGMA(g)+ states are clearly visible. Oscillations in the associated Franck-Condon factors reflect the structure of the triplet ground state wave function. Our results clearly demonstrate the potential of photoassociation spectroscopy as a new probe of molecular structure.