![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
The phase-cycled Jeener-Broekaert sequence was used to simultaneously measure the deuterium Zeeman (T 1z) and quadrupole (T 1q) spin-lattice relaxation times in the mesophases of 4-n-butoxybenzylidene-4′-n-octylaniline-2,3,5,6-d4 at a Larmor frequency of 15.4 MHz. The derived spectral densities of motion J 1(wo) and J 2(wo) increase with decreasing temperature in the nematic, smectic A and smectic B Phases and show a discontinuity similar to that of the quadrupolar splitting at the SA to SB phase transition. The angular dependence of T 1z and T 1q were measured in the smectic B phase, thus allowing us to obtain J 1(wo) and J 2(wo). Within experimental error, the spectral densities J p(w) (p = 1,2) are in the white spectrum regime. Molecular reorientation seems to be a dominant relaxation mechanism for the aniline deuterons and is discussed in terms of a small step rotational diffusion model.