Probing modulated liquid crystal media with dielectric spectroscopy

We use impedance spectroscopy to probe modulated liquid crystals. Chiral nematic samples are characterized and fabricated with a fixed amount of chiral dopant and Smectic-A in different geometries. The data are adjusted with a Poisson-Nernst-Planck (PNP)-like model. The low-frequency behavior of the conductivity is studied, and the behavior is associated with the ionic diffusivity across the cell. Diffusion across layered structures, contrary to what occurs when the structures are not layered, requires permeation of ions, which is reflected in the very low exponent characterizing diffusivity, indicating a cage-like behavior diffusion. Thus, this simple non-destructive technique can be used to probe the morphology of the material.