No abstract

In photoassociation spectroscopy, the line intensities of a given vibrational progression exhibit zero-signal modulation reflecting the node structure of the s-wave ground state wave function of two free colliding atoms. This leads to the determination of the scattering length. We performed photoassociation of cold Cs atoms polarized in the Zeeman sublevel f = 4, m(f) = 4. We analyzed the intensities of the lines associated with the Cs2 0(-)(g) state dissociating to the 6s(1/2)+6p(3/2) asymptote. This yields a value of the Cs triplet state scattering length, a(T) = -530a(0), while consistency requirements impose a value of the multipole ground state molecular coefficient, C6 = 6510 a.u.

Ultracold molecules are formed via photoassociation in a polarized sample of cold cesium atoms. The rate of molecule formation is controlled by tuning a magnetic field. The radial dependence of the colliding wave function is probed by the photoassociation spectroscopy technique. We have in this way observed the drastic influence of the magnetic field in a broad Feshbach resonance for f = 3, m = 3 colliding atoms and for magnetic fields up to 30 G.