  We demonstrate efficient transfer of ultracold molecules into a deeply bound
rovibrational level of the singlet ground state potential in the presence of an
optical lattice. The overall molecule creation efficiency is 25%, and the
transfer efficiency to the rovibrational level |v=73,J=2> is above 80%. We find
that the molecules in |v=73,J=2> are trapped in the optical lattice, limited by
optical excitation by the lattice light. The molecule trapping time for a
lattice depth of 15 atomic recoil energies is about 20 ms. We determine the
trapping frequency by the lattice phase and amplitude modulation technique. It
will now be possible to transfer the molecules to the rovibrational ground
state |v=0,J=0> in the presence of the optical lattice.
