MODELING OF THE OPTICAL PROPERTIES OF MULTICOMPONENT FILMS ON SMALL ISOTROPIC SPHERES

The model developed recently by us for calculating the optical properties of a small isotropic sphere, with a radially uniaxial coating of molecules, is extended here to include multicomponent coatings in an approximation in which the molecules, treated as point polarizable, are assumed to be randomly distributed over spherical shells of close to the same radius. Calculations are performed to determine the effect of coadsorption of Xe on the infrared absorption properties of CO2 physisorbed on silica particles with the molecular axes oriented radially. The calculations confirm an earlier suggestion by one of us that the effect of coadsorption of an ‘‘inert molecule,’’ such as Xe, on the infrared absorption spectrum of an adsorbed species can be used to provide information on the orientation of the species with respect to the local surface normal.