Polarization electric field dependence

Electric field dependent electronic polarization in a molecule yields a field dependent dipole moment ... 

Dielectrophoresis is the translational motion of neutral matter owing to polarization effects in a non-uniform electric field. Depending on matter or electric parameters, different particle populations can exhibit different behavior, e.g. following attractive or repulsive forces. DEP can be used for mixing of charged or polarizable particles by electrokinetic forces [48], In particular, dielectric particles are mixed by dielectrophoretic forces induced by AC electric fields, which are periodically switched on and off. 

In a few cases, polysilanes are chromotropic in the presence of an electric field (electrochromism). This was first shown for the copolymer (CF3CI BCtBSiMejn-co-t/i-PrSiMe)m, n m = 45 5558. In an electric field of 108 Vm 1the electronic absorption band for this polymer intensified by 50% and shifted from 294 to 299 nm. The changes are reversible when the field is removed. This is apparently the first example of electric field dependence of the absorption for any polymer, unaccompanied by electrochemical oxidation or reduction. The structural change accompanying this chromotropism is not understood. Other polysilanes with polar side groups may also show electrochromic behavior, but have not yet been studied. 

Effect of an electric field on a polar bond. A bond with a dipole moment (as in HF, for example) is either stretched or compressed by an electric field, depending on the direction of the field. Notice that the force on the positive charge ism the direction of the electric field (E), and the force on the negative charge is in the opposite direction. 

Table 8). This permits the interpretation of experimental data by using the electro-optical properties of flexible-chain polymers in terms of a worm-like chain model However, EB in solutions of polyelectrolytes is of a complex nature. The high value of the observed effect is caused by the polarization of the ionic atmosphere surrounding the ionized macromolecule rather than by the dipolar and dielectric structure of the polymer chain. This polarization induced by the electric field depends on the ionic state of the solution and the ionogenic properties of the polymer chain whereas its dependence on the chain structure and conformation is slight. Hence, the information on the optical, dipolar and conformational properties of macromoiecules obtained by using EB data in solutions of flexible-chain polyelectrolytes is usually only qualitative. Studies of the kinetics of the Kerr effect in polyelectrolytes (arried out by pulsed technique) are more useful since in these... 

An example of such a series of transient experiments for a sample of paper without conductive additives (softwood Kraft pulp, 450 CSF, 80 g/m2 basis weight, Sample 1), is shown in Fig. 16. This series of transient currents represents the electric field dependence of charge transport associated with mobile ions within the water associated with the fibrous network of the papor. The initial transient current, labeled (a), corresponds to the first application of an electric field (E = 2.5 x 103 Volts/cm) to the new sample. After reversing the polarity of the power supply an electric field of the same magnitude is applied to the sample which leads to the transient current shown by label (b) in Fig. 16. (N.B. the scale of the ordinate is different for... 

Figure 5. Electric field dependence of the diffraction efficiency of the non-Bragg orders. The field polarity convention is illustrated in Figure 2.

Thus, in general, the induced dipole moment will reach a saturation value m. As pictured in Figure 2, a restricted charge displacement may be accompanied by an orientational charge of the dipole axis. The electric field dependence of the total moment may be described in terms of coth functions as in the case of the counterion polarization in linear polyelectrolytes. See also Yoshioka et... 

Dielectrophoresis (DEP) is a phenomenon different from electrophoresis (EP). In fact, any nonpolar material experiences a certain degree of polarization when exposed to an electric field. Depending on the material properties of the particle, electric dipoles are generated on opposing ends of the particle. The DEP force is due to the interaction between the dipole induced by an appfied electric field and the spatial gradient of that electric field. The general expression of the DEP force exerted on a particle in an electric field is... 

The polarizable point charge (PPC) model of Kusalik et al [82,83] retains the simplicity of most non-polarizable three-site models while incorporating the nonadditivity polarization through polarizable point charges that fluctuate in response to the local electric field. The novelty in this model is that the electric-field dependence of the point charges has been determined by quantum-chemical calculations using a commercial package. 

Feshbach resonances can in principle also be observed by tuning a static electric field [87] or an optical (or RF, microwave, etc.) field [88,89] or a combination of both [87,90]. The electric field dependence of PA for polar molecules can now be accurately modeled [91,92]. 

For simplicity, ignoring the effect of the polarization electric field on the elastic deformation [23], it is assumed that changes with Y at a constant rate. According to Kawaida etal. [24], the wavelength dispersion of the refractive indices was taken into account in the calculation of transmission. The wavelength dependences of the memory angles and the transmission spectra of CS-1014 0 — 20.0° and 6 — 18.0°) and PSI-A-2001 (0p = 15°) were calculated. 

Figure 9.28 illustrates the electro-optic responses observed at two 0 s 0° and 30°, where 0 is the angle between the layer normal and one of the crossed polarizer directions. As shown in Figure 9.28 [92], the electric field dependence of transmittance at 0 = 0° shows the typical thresholdless, hysteresis free, V-shaped switching. From the electro-optic measurements at every 5° of 0, the transmittance T versus 0 was obtained at given electric fields. Figure 9.29(a) shows three examples of T versus 0 curves at applied fields of 0, +6, and 6 V/pm [92]. The transmittance T is described by... 

Standard energy-optimized basis sets are not suitable for accurate calculations of electric polarizabilities. The simplest solution - adding the necessary polarization and diffuse functions - makes the basis sets too large to enable efficient calculations for large molecules. Significantly smaller basis sets, designed considering the electric-field dependence of the orbitals (Benkova et al. 2005 Sadie) 1988), provide results of similar or better quality at lower computational cost. 

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