Study of optical anisotropy in thin molecular layers by total internal reflection ellipsometry

Variable angle total internal reflection ellipsometry (TIRE) has been utilized to reveal anisotropy in the optical response of fragmented antibody (frag-Ab) monolayer. Optical anisotropy has been taken into account in determination of optical constants of an organic layer. The orientation of frag-Ab on the surface has been characterized by using the uniaxial model in the analysis of TIRE data. Regression results have shown that the largest dimension of frag-Ab molecule (11.5 nm) is oriented parallel to the gold surface with a slight tilt (13°). Due to the tilt, the distance between the recognition sites of frag-Ab and the gold surface increases resulting in an enhanced reactivity of the molecules and better steric accessibility.