Production of Long-Lived UltracoldLi2Molecules from a Fermi Gas

We create weakly bound ${\mathrm{L}\mathrm{i}}_2$ molecules from a degenerate two component Fermi gas by sweeping a magnetic field across a Feshbach resonance. The atom-molecule transfer efficiency can reach $85\%$ and is studied as a function of magnetic field and initial temperature. The bosonic molecules remain trapped for 0.5 s and their temperature is within a factor of 2 from the Bose-Einstein condensation temperature. A thermodynamical model reproduces qualitatively the experimental findings.