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DETERMINATION OF THE 0^-_g PURE LONG RANGE POTENTIAL CURVE OF Rb₂ AND Cs₂; APPLICATION TO ULTRACOLD MOLECULES FORMATION.

R. F. GUTTERRES, C. AMIOT, O. DULIEU AND F. MASNOU-SEEUWS, Laboratoire Aimé Cotton, Bât 505, Campus d'Orsay 91405, Orsay Cedex, France.

This work presents an accurate study of the 0^-_g(P_3/2) pure long range electronic state of the ⁸⁷Rb(5S)-⁸⁷Rb(5P_3/2) and ¹³³Cs(6S)-¹³³Cs(6P_3/2) molecular systems. Generalized simulated annealing method was used in order to reduce the high resolution spectral data provided by photoassociative spectroscopy of ultra cold ⁸⁷Rb and ¹³³Cs atoms. The analysis has allowed the determination of the effective dispersion parameters, the chemical exchange energy contribution as well as the dissociation energy concerning the analytical potential representation of the 0^-_g(P_3/2) state for both, Rb₂ and Cs₂, molecules. A detailed comparison with the potential curves obtained through RKR procedure is performed, and the consequences for ultracold molecules formation rates are discussed.