Coupled singlet-triplet analysis of two-color cold-atom photoassociation spectra

We describe a method that is well suited to analysis of the bound states of the alkali-metal dimers near their dissociation limit. The method combines inverse perturbation theory, coupled-channel bound-state theory, and the accumulated phase method to treat the short-range part of the molecular potentials. We apply this method to analyze the bound-state energies measured in a two-color photoassociation experiment in an ultracold 85Rb gas. This analysis yields information on the interactions between ultracold 85Rb atoms that is important to the understanding of ultracold Rb collisions and Bose-Einstein condensation