Measurement of the dispersion of a liquid analyte using surface plasmon resonance: a theoretical approach

A theoretical study of a spectral method based on surface plasmon resonance (SPR) to measure the dispersion of a liquid analyte is presented. A setup with an SF10 glass prism and a gold coated SF10 slide is proposed and the SPR phenomenon in the Kretschmann configuration is analyzed in the spectral domain. Using the material dispersion of the SPR structure and the analyte, the resonance wavelength for the ratio of the reflectances of p- and s-polarized waves is determined for different angles of incidence. Using two new procedures, these theoretical values are utilized in obtaining the refractive index of the analyte as a function of the resonance wavelength. The dispersion of the analyte thus retrieved is compared with the one used in the model and it is concluded that one of the procedures is more accurate than the other. The applicability of the new method is demonstrated for two different analytes, water and ethanol, and the measurement range is specified.