Formation of ColdCs2Molecules through Photoassociation

We have performed photoassociative spectroscopy of cold Cs atoms in a vapor-cell magneto-optical trap, within $10{\mathrm{cm}}^{-1\mathrm{}}$ below the dissociation limit $6s{}_{}{}^2{}_{}{}^{}S_{1/2}^{}{}_{}{}^{}+6p{}_{}{}^2{}_{}{}^{}P_{3/2}^{}{}_{}{}^{}$. Our detection method is based on pulsed-laser photoionization of ${\mathrm{Cs}}_2$ molecules, selectively detected through a time-of-flight mass spectrometer. Temporal and spatial analysis of ${\mathrm{Cs}}_2^{+}$ ions show for the first time the formation of translationally cold ${\mathrm{Cs}}_2$ triplet ground state molecules, at a temperature $T\sim 300\mu \mathrm{K}$.