Surface plasmon resonance (SPR) reflectivity measurements are surface-sensitive, spectroscopic methods that can be used to characterize the thickness and/or index of refraction of ultrathin organic and biopolymer films at gold, silver surfaces.
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SPR imaging detects the presence of a biopolymer on a chemically modified gold surface by the change in the local index of refraction that occurs upon adsorption.
Research Papers are on , Uiversity of California, Irvine page and also at