Triplet s-wave resonance in Li-6 collisions and scattering lengths of Li-6 and Li-7

The triplet s-wave scattering length of Li-6 is determined using two-photon photoassociative spectroscopy of the diatomic a (3) Sigma(u)(+) State of Li-6(2). The measured binding energy of the highest-lying bound state, combined with knowledge of the potential, determines the s-wave scattering length to be (-2160+/-250)a(0), where a(0) is the Bohr radius. This extraordinarily large scattering length signifies a near-threshold resonance. A complete table of singlet and tripler scattering lengths for collisions involving Li-6 and Li-7 determined from this and our previous spectroscopic investigations is given.