Browsing by Author "Dalgarno, A."

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    Photoabsorption by Ultracold Atoms and the Scattering Length
    (American Physical Society, 1995) Côté, R.; Dalgarno, A.; Sun, Y.; Hulet, R.G.; Rice Quantum Institute
    It is shown that photoabsorption in a gas of ultracold atoms depends on the sign and magnitude of the scattering length in the scattering of a pair of atoms. Measurements of fluorescence in 7Li are interpreted to show that the triplet scattering length is negative and the singlet scattering length is positive.
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    Singlet s-wave scattering lengths of Li6 and Li
    (American Physical Society, 1996) Abraham, E.R.I.; McAlexander, W.I.; Gerton, J.M.; Hulet, R.G.; Côté, R.; Dalgarno, A.; Rice Quantum Institute
    Photoassociation of ultracold lithium atoms into bound vibrational levels of the AΣu+1 excited state is used to probe the XΣg+1 ground-state interaction potential of Li26 and Li27. It had been predicted that the s-wave photoassociation signal strength would pass through a minimum as a function of vibrational level for positive s-wave scattering length. We report the observation of this novel effect, and use the location of the minimum to precisely determine the singlet s-wave scattering length for both isotopes. The sensitivity of this technique is demonstrated by distinguishing the minima for collisions involving Li7 atoms in different hyperfine states.
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    Triplet s-wave resonance in Li6 collisions and scattering lengths of Li6 and Li7
    (American Physical Society, 1997) Abraham, E.R.I.; McAlexander, W.I.; Gerton, J.M.; Hulet, R.G.; Côté, R.; Dalgarno, A.; Rice Quantum Institute
    The triplet s-wave scattering length of Li6 is determined using two-photon photoassociative spectroscopy of the diatomic a3Σ+u state of Li26. 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)a0, where a0 is the Bohr radius. This extraordinarily large scattering length signifies a near-threshold resonance. A complete table of singlet and triplet scattering lengths for collisions involving Li6 and Li7 determined from this and our previous spectroscopic investigations is given.