PHENOMENOLOGICAL MODEL FOR OPTICAL-PROPERTIES OF DIELECTRIC SURFACES

A phenomenological model is proposed for the surfaces of dielectric or excitonic media. The reflection of the elementary excitations is described in terms of a parameter of the form p = p0exp(iφ). This describes a change of phase upon reflection and, with 0 ≤ P0 ≤ 1, allows for surface roughness, which entails amplitude damping of the reflected excitation. The model is developed consistently with energy conservation, which plays a central role in this analysis. Combined with the idea of a dead layer this model reproduces the essential observed features of the normal incidence excitonic reflectance spectra without need to assume too large changes in the dead layer thickness. © 1979.