Spin-lattice dispersion in nematic and smectic-Amesophases in the presence of ultrasonic waves: A theoretical approach

We present a theoretical study of the Larmor frequency dependence of the nuclear spin-lattice relaxation caused by order director fluctuations for both nematic and smectic-A mesophases. The analysis is focused on the case where the molecular system is subjected to sonication during the relaxation process. The departure from the nonsonicated case is discussed for various values of the involved parameters. Two different approaches are discussed for the smectic case.