Formation of cold Cs

We report on the formation of translationally cold Cs2 ground state molecules through photoassociation in the $1_{u}$ attractive molecular state below the $6s\,_{1/2}+6p\,_{3/2}$ dissociation limit. The cold molecules are obtained after spontaneous decay of photoassociated molecules in a MOT and in a dark SPOT. We also used polarized atoms, in the f=3, $m_{f}=+3$ Zeeman ground state. Purely asymptotic and adiabatic calculations including hyperfine interaction and rotation are in excellent agreement with observed structures. As expected, the $1_{u}$ state is actually a pure long-range state, consisting of paired atoms, uniquely linked by the first terms of the multipole expansion of the electrostatic interaction. A temperature of 20$_{-5}^{+15}~\mu$K has been measured for the molecular cloud