Separate determination of thickness and optical parameters by surface plasmon resonance: accuracy consideration

The reliability and precision of characterizing surface layers by the surface plasmon resonance (SPR) method was evaluated with relation to the experimental conditions and the strategy of extracting the film parameters. Consideration is given to sensor applications of the SPR phenomenon, to separate extraction of optical constants and thickness of the layer, and to determination of the total quantity of the material constituting the surface coverage. A computational scheme for modeling the SPR resonance for multilayer assembly, based on the Abeles matrix formalism, is presented. It is demonstrated that an improper choice of the angle range for the measurements may result in ambiguity in determining the refractive index n and the film thickness d. Nevertheless, the total quantity of material in the film can be estimated with reasonable accuracy even when correct separate derivation of n and d parameters is hampered by experimental errors and an inadequate theoretical model of the layered system. (Author)