Dipole relaxation near boundaries

The influence of a solid-liquid interface on the relaxation of a point dipole embedded in the liquid side is discussed. The dielectric friction of a dipole as a function of its distance from a boundary is calculated. The calculations are carried out assuming a nonlocal dielectric function of the liquid, characterized by a typical correlation length which may depend on temperature. The corrections to the relaxation of a dipole due to the presence of a boundary are shown to be small. Larger corrections can be introduced by postulating structural changes in the nature of the liquid near the boundary. As a demonstration we apply the proposed formalism in the study of temperature and pore size dependence of a dipole relaxation.