  Recently we demonstrated the formation of ultracold polar LiCs molecules in
deeply bound levels of the X1S+ ground state, including the rovibrational
ground state [J. Deiglmayr et al., Phys. Rev. Lett. 101, 133004 (2008)]. Here
we report on the first experimental determination of the permanent electric
dipole moment of deeply bound LiCs molecules. For X1S+,v"=2 and v"=3 we measure
values of mu=5.5(2) Debye and 5.3(2) Debye respectively.
