Static and dynamic light scattering from the nematic wetting layer in an isotropic liquid crystal

By the use of the evanescent wave technique the fluctuations of the nematic wetting layer in an isotropic liquid crystal have been investigated by static and dynamic light scattering. As the homeotropically oriented layer is birefringent, its critical angles of total internal reflection for the ordinary and extraordinary rays differ from that of the bulk. For a suitable selected angle of incidence there is a propagating extraordinary ray in the layer which becomes evanescent in the bulk. In this case the scattering of the layer is enhanced and therefore well accessible to the measurement. It shows up to be strongly dependent on the scattering vector component parallel to the interface, in contrast to the bulk scattering with no marked dependence on the scattering vector. At angles of incidence with evanescent waves in bulk and layer, a broad long time decay shows up, which seems to be typical for evanescent measurements and can be described with an algebraic functional dependence.