Theory of dipolar relaxation in lamellar system: Application to lyotropic liquid crystals

This is the authors' abstract. We don't add key points for this paper.

We propose a theory of dipolar spin relaxation for lamellar geometry where one of the spin species diffuses on an infinite plane while the other diffuses within an infinite layer of finite thickness. Analytical expressions of the frequency dependence of the spectral densities and spin relaxation rates are given. The theoretical frequency variation of the longitudinal relaxation rate appears to be drastically dependent of the anisotropic diffusion ratio and on the thickness of the layer. An application of this theory to lamellar lyotropic liquid crystal gives the spatial distribution of an organic counterion solute in the bilayer from the frequency variation of the 31P longitudinal relaxation rates of the surfactant. This gives some information about the surfactant-organic counterion interaction and the hydration degree of the phosphate group.