Phase characterization ellipsometry

Drevillon B (1993) Phase modulated ellipsometry from the ultraviolet to the infrared in-situ application to the growth of semiconductors. Progress in Crystal Growth and Characterization of Materials 27 1-87. 

As discussed above, the reflection of linearly polarized light from a surface generally produces elliptically polarized light, because the parallel and perpendicular components are reflected with different efficiencies and different phase shifts. These changes in intensity and phase angle can be analyzed to characterize the reflecting system. This approach is called ellipsometry. 

Little is known about infrared refractive indices of organic compounds, and only very few such studies related to liquid crystals are reported. To some extend this is due to the fact that special techniques and even dedicated equipment are required. On the other hand birefringence can be derived from the polarization pattern produced by the phase difference between the ordinary and the extraordinary beam. This experiment had been outlined by Born and Wolf (1980) and was applied to liquid crystals by Wu et al. (1984). The procedure is primarily suitable in transparent regions, for a more comprehensive optical characterization it should be extended to complete ellipsometry (Reins et al., 1993). Results obtained by infrared-spectroscopic ellipsometry are shown in Figs. 4.6-5 and 4.6-6. 

To obtain the morphology information, including phase separation and crystalline, we can now use microscopic techniques, atomic force microscopy, transmission electron microscopy, electron tomography, variable-angle spectroscopic ellipsometry. X-ray photoemission spectroscopy, and grazing-incidence X-ray diffraction. The detailed information of this characterization methods can be found from the specific reference (Li et al., 2012 Huang et al., 2014). 

The properties of adsorbed layers at liquid interfaces can be determined either indirectly by thermodynamic methods or directly by means of some particular experimental techniques, such as radiotracer and ellipsometry. For adsorbed layers of synthetic polymers or biopolymers the advantages of the ellipsometry technique become evident as it yields information not only on the adsorbed amount but also on the thickness and refractive index of the layer. The theoretical background of ellipsometry with regard to layers between two bulk phases has been described in literature quite frequently (243). In brief, the principle of the method assumes that the state of polarization of a light beam is characterized by the amplitude ratio Ep E and the phase difference (8 — 8g) of the two components of the electric-field vector E. These two components Ep and E are parallel (p) and normal (s) to the plane of incidence of the beam and given by... 

In order to deposit the SBDC photoiniferter on the hydroxy-lated Si/Si02 substrates from the vapor phase, a 10 /tL drop of the photoiniferter was placed in a desiccator, which was evacuated for 60 s with a rotary vane pump to evaporate residual solvent. Thereafter, the freshly cleaned Si/Si02 substrates were placed around the SBDC drop, and the desiccator was evacuated again, this time for 60 min (p 10 mbar). After closing the valve to the vacuum pump, the photoiniferter was allowed to adsorb onto the silicon oxide substrates for > 48 h until atmospheric pressure was reached. Prior to UV-induced polymerization reactions, the photoiniferter-modified substrates were ultrasonicated in toluene for 2 min to remove physisorbed initiator before the initiator layer was characterized by variable angle spectroscopic ellipsometry and static contact-angle measurements. 

Rapid advances in computer technolc during the past decades have made possible the automation of ellipsometry instruments and data analysis [5]. Developments in spectroscopic ellipsometry, based on rapid data collection, can offer the real-time characterization of dynamic behavior of thin layers [33,34], including the evaluation of structural changes, phase separation, or the swelling of polymer films [17]. 

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