Localized electrical effects separation

Attempts have also been made to separate non-specific effects of the local electrical field from hydrogen-bonding effects for a small group of ionic liquids through the use of the k scale of dipolarity/polarizability, the a scale of hydrogen bond donor acidity, and the (i scale of hydrogen bond basicity (see Table 3.5-1) [13, 16]. 

Taft and his coworkers14-16 developed a diparametric model which separated the electrical effect into contributions from the inductive (actually the field) and resonance effects. This separation depends on the difference in the extent of electron delocalization when a substituent is bonded to an sp3 -hybridized carbon atom in one reference system and to an sp2-hybridized carbon atom in another. As the first case represents minimal delocalization and the second extensive delocalization, we have referred to the two effects as the localized and delocalized electrical effects. This diparametric electrical effect model can be written in the form ... 

This electrokinetically driven micro mixer uses localized capacitance effects to induce zeta potential variations along the surface of silica-based micro channels [92], The zeta potential variations are given near the electrical double layer region of the electroosmotic flow utilized for species transport. Shielded ( buried ) electrodes are placed underneath the channel structures for the fluid flow in separate channels, i.e. they are not exposed to the liquid. The potential variations induce flow velocity changes in the fluid and thus promote mixing [92],... 

One dimensional geometry Because the scale of phase separation in the junction is small compared to the device size, an effective medium approach is often applied, and one-dimensional symmetry assumed. This means neglecting the effect of local electric fields at the interface, and differences in behavior between electrons or ions that are near or further from the interface or grain boundaries. The effect of electrolyte on electron transport can be included through an effective diffusion coefficient. 

The foregoing sections described how various NLO phenomena can be imderstood in terms of the nonlinear susceptibilities. In this section, those susceptibilities are described in terms of the polarizabilities and hyperpolarizabiUties, which characterize the separation of charge due to the electric-field at the molecular level. Major factors considered in bridging between the microscopic and the macroscopic properties include (1) local field effects, (2) orientation effects, (3) methods for incorporating NLO chromophores into a polymer to optimize the bulk properties, and (4) limits to the optimization of bulk properties through additive effects of the microscopic response. 

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