Triplet s-wave resonance inLi6collisions and scattering lengths ofLi

Abstract

The triplet s-wave scattering length of 6 Li is determined using two-photon photoassociative spectroscopy of the diatomic a 3 ⌺ u ϩ state of 6 Li 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 ͑Ϫ2160Ϯ250)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 triplet scattering lengths for collisions involving 6 Li and 7 Li determined from this and our previous spectroscopic investigations is given.

Simple variational approach for an interacting Fermi trapped gas

“…It exhibits magnetic tunable Feshbach resonances that enable the variation of the scattering length from strongly repulsive to strongly attractive. In fact, an anomalously large and negative scattering length α 0 = −2160 a 0 has been already measured [12]. The coupling constant corresponding to this value of α 0 , for a typical trap of mean frequency ω 0 ∼ 3kHz is g = −0.725.…”

Feshbach resonances with large background scattering length: Interplay with open-channel resonances

“…In other situations a bg can be large and negative, indicating that the interaction potential has a virtual state near threshold. Examples here are 85 Rb with a bg = −443a 0 [14], and 6 Li where a bg Ϸ −2000a 0 [29,30]. In these cases, the nonresonant description of the background scattering process is not correct.…”

Formation of fermionic molecules via interisotope Feshbach resonances

“…In the second analysis we investigate 7 Li as well; however, we only do a mass scaling for the triplet potential. Our total set of 6 Li experiments comprises six data points: the zero crossing of the scattering length of a system in the two lowest hyperfine states [18,19]; in the same spin state configuration, the positions of the narrow [20] and wide [7] Feshbach resonances; and the measurement of the scattering length in the lowest and third to lowest hyperfine state [21] and the binding energy of the most weakly bound triplet state [22].…”