  A theoretical study is presented of surface waves at a monomolecular
surfactant film between an isotropic liquid and a nematic liquid crystal for
the case when the surfactant film is in the isotropic two-dimensional fluid
phase and induces homeotropic (normal to the interface) orientation of the
nematic director. The dispersion relation for the surface waves is obtained,
and different surface modes are analyzed with account being taken of the
anchoring induced by the surfactant layer, the curvature energy of the
interface, and the anisotropy of the viscoelastic coefficients. The dispersion
laws for capillary and dilatational surface modes retain structure similar to
that in isotropic systems, but involve anisotropic viscosity coefficients.
Additional modes are related to relaxation of the nematic director field due to
anchoring at the interface. The results can be used to determine different
properties of nematic-surfactant-isotropic interfaces from experimental data on
surface light scattering.
