Orientational, polarization

CDAD Circular dichroism photo- Uses circularly polarized Orientation of adsorbed... 

When light that has experienced such retardation is viewed by a polarizer oriented at 90° to the original plane of light polarization, the two components of the original light beam interfere with one another. This results in a change in color and intensity of the observed light. Observed colors correspond to different levels of retardation at that point, which in turn correspond to stress levels. 

Relaxation processes are probably the most important of the interactions between electric fields and matter. Debye [6] extended the Langevin theory of dipole orientation in a constant field to the case of a varying field. He showed that the Boltzmann factor of the Langevin theory becomes a time-dependent weighting factor. When a steady electric field is applied to a dielectric the distortion polarization, PDisior, will be established very quickly - we can say instantaneously compared with time intervals of interest. But the remaining dipolar part of the polarization (orientation polarization, Porient) takes time to reach its equilibrium value. When the polarization becomes complex, the permittivity must also become complex, as shown by Eq. (5) ... 

Taken from the three spontaneous symmetry-breaking events leading to this layer structure [formation of layers with long-range orientational order of the director (Sm), tilt of the director from the layer normal (C), and polar orientation of the molecular arrows (P)], we term phases of this type SmCP. All of the complex textures and EO behavior of NOBOW in the B 2 phase can be understood in terms of various stacking modes of SmCP layers as shown in Figure 8.23. 

FIGURE 5.8 Electroluminescence from an LED based on ITO-rubbed PPV-aligned poly(9,9-dioctyl fluorene)/Ca recorded through a polarizer oriented parallel (triangles) and perpendicular (circles) to the orientation direction. (From Whitehead, K.S., Grell, M., Bradley, D.D.C., Jandke, M., and Strohriegl, P., Appl. Phys. Lett., 76, 2946, 2000. With permission.)... 

The emitted light is detected along y through a polarizer oriented either along z (Fz) or along x (Fx). In fluorescence polarization studies with continuous excitation (steady-state experiments), the emission anisotropy r and the emission polarization p are defined in eqs 8a and 8b. 

We can further describe the polarization, P, according to the different types of dipoles that either already exist or are induced in the dielectric material. The polarization of a dielectric material may be caused by four major types of polarization electronic polarization, ionic (atomic) polarization, orientation polarization, and space-charge (interfacial) polarization. Each type of polarization is shown schematically in Figure 6.24 and will be described in succession. In these descriptions, it will be useful to introduce a new term called the polarizability, a, which is simply a measure of the ability of a material to undergo the specific type of polarization. 

Substances that can rotate the orientation of plane-polarized light are said to have optical activity. Measurement of this change in polarization orientation is called polarimetry, and the measuring instrument is called a polarimeter. 

Electret. The electrical equivalent of a permanent magnet. When a block of dielectric material, such as carnauba wax, is allowed to be solidified in a strong electric field it acquires a permanent state of electrostatic polarization (orientation of molecules) in the direction of the field. 

This account has summarized several of our approaches to the preparation of electric-field-aligned chromophoric polymers for second order NLO applications. Molecular design has been employed wherever possible to arrive at structures that probe particular aspects of the polar orientation issue. The rich variety of accessible organic structures has enabled us to consider the orientation problem from a variety of points of view, and to indicate by example the manner in which multifunctional organic synthesis may play a role in the fabrication of oriented materials. 

Experimental Evidence of Polar Orientation of the o-Nitroalkoxv System in the C Phase... 

Figure 30 Schematic representation of the polar orientation of the dyes in the multilayers of zirconium phosphate-phosphonate interlayers. This scheme is based on the known structures of Zr(H0P03)2 and related organic Zr phosphonate salts. (From Ref. 65a. Copyright 1991 The American Association for the Advancement of Science.)...

The intensity decays are often measured through a polarizer oriented at some angle such as about 55° from the vertical z-axis to avoid the effects of... 

Figure 19.20 Piezoelectric vibration maps of phase ((a), (c)) and amplitude ((b), (d)) (3x3 /um2) of a fatigued Pt-PZT-Pt structure after positive ((a), (b)) and negative ((c), (d)) poling. Bright and dark phase areas correspond to bottom-to-top and top-to-bottom polarization orientations, respectively.

The maps on the left side show the phase, i.e. the polarization orientation. Those on the right side show the corresponding amplitude and the used AC-voltages is indicated. Of particular interest is the evolution of the marked dark area in Figure 19.24 top-left. This area should... 

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