Study of Molecular Dynamics In the Hexatic SF Phase of TBDA: Comparison with Results from the Crystal SG and the Sc Phases

The molecular dynamics in the smectic C, F and G phases of the compound TBDA is studied by proton NMR relaxation. The spin-lattice relaxation time T1 was measured for several temperatures spanning the three mesophases in the frequency range of 4–80 MHz. Measurements of the spin-lattice relaxation time in the rotating frame T lp were also performed at a field of 4.9 Gauss and for the same set of temperatures. The results were analyzed in terms of the potential contributions of the different molecular motions for the relaxation process; namely reorientations, translational self-diffusion and for the Sc phase smectic layer undulations also.