Guided wave measurement techniques

As a result of the heterogeneous distributions of electrical charge and chemical functionalities present on the surface of most proteins, the adsorption of proteins to solid substrates of differing surface properties may produce different molecular orientations. The optical thickness of protein layers can be evaluated by using el-lipsometry, surface plasmon resonance, or guided wave perturbation. When a chro-mophore of the protein is used as a probe, polarized spectroscopic techniques are found to be applicable to measure the tilt angle of the heme moiety in protein films. Macdonald and Smith used SERRS... 

Measurements of the physical properties of nematic liquid crystals by guided wave techniques... 

In order to make meaningful physical measurements on monolayer and multilayer L-B films, it is essential that the films be characterized to determine the molecular structure, unformity of the film and layer-to-layer structural correlation. To probe the molecular structure, our research group has utilized a variety of spectroscopic techniques such as u.v.-visible spectroscopy, ATR-IR, wave-guide Raman, surface-plasmon wave Raman spectroscopy and inelastic electron tunneling. The spectroscopic techniques... 

The thickness and the refractive index of the polymer film can also be measured more precisely by optical waveguiding techniques. The planar wave guide technique in which the light is confined in one direction only is widely used for this purpose Table 1 summarizes some of the linear optical properties of photoreactive polymer films. 

The new near infrared wave guide coupling technique can be used for the determination of the three dimensional refractive indices of films opaque in the visible region. This technique is appropriate for other electroactive polymer systems providing a window exists in the visible or near infrared spectrum where measurements can be made. Applying this technique to PANI films has clearly shown that spin coated films show some planar character in the thickness direction. Unidirectional stretching of freestanding spin-coated PANI film leads to increased orientation in the deformation direction, and conversion from a planar to a more uniaxial structure. Similar studies have been carried out on PANI films formed from NMP solutions.[ll]... 

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