Determine layer unique refractive index and thickness with MP-SPR

Application Note #128

Illustration of the two wavelength analysis principle. Black and orange line are RI – d continuum answers for both of the wavelengths. Dashed line is sifted curve based on the dRI/dλ value, which enables a unique solution for the thickness and RI.

Multi-Parametric Surface Plasmon Resonance (MP-SPR) can be used to determine unique thickness and refractive index (RI) of ultrathin films without prior knowledge of the RI or the thickness of the layer. Polyelectrolyte multilayer was measured using MP-SPR two wavelength method and analysed by LayerSolver™ software module. Thickness of 5 bilayers was found to be 16.8 nm and RI 1.48 at 785 nm.

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