Spectroscopic ellipsometry medium

Spectroscopic ellipsometry allows to detect small shifts of the phase transition temperature introduced either by a variation of the thermo-responsive polymer or the liquid environment. The latter dependency was demonstrated by Schmaljohann et al. (2003) for buffer solutions and cell culture medium and by Cordeiro et al. (2009) for artificial sea water. In both cases, the electrolyte shifts the transition temperature toward lower values. 

The optical properties and thickness of the films were quantified using spectroscopic ellipsometry (M-2000, J.A. Woollam). Film porosity was calculated from the Bruggemann effective medium approximation (BEMA) model [11,54], assuming that only two phases existed amorphous silica and voids. The refractive index of the film was determined and directly translated into the film porosity, knowing the refractive index of the wall framework. The wall was assumed to be solely amorphous silica with a reported refractive index of 1.458. The film porosity calculated was found to be in the range of 50-60%. 

Aspnes, Theeten, and Hottier made spectroscopic ellipsometry measurements of a surface with induced roughness, and examined calculations with various approximations based on the effective medium model represented by the following relation for the effective dielectric constant < > for a composite layer composed of materials 1 and 2 dispersed in a host medium ... 

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