Charge bound

Beyond the IHP is a layer of charge bound at the surface by electrostatic forces only. This layer is known as the diffuse layer, or the Gouy-Chapman layer. The innermost plane of the diffuse layer is known as the outer Helmholtz plane (OHP). The relationship between the charge in the diffuse layer, o2, the electrolyte concentration in the bulk of solution, c, and potential at the OHP, 2> can be found from solving the Poisson-Boltzmann equation with appropriate boundary conditions (for 1 1 electrolytes (13))... 

Simultaneous measurements of d and osmotic pressure provide a relation between the separation of bilayers and their mutual repulsive pressure. Measurement of the electrostatic repulsion is, in fact, a determination of the electrostatic potential midway between bilayers relative to the zero of potential in the dextran reservoir. The full nonlinear Poisson-Boltzmann differential equation governing this potential has been integrated (I) from the midpoint to the bilayer surface to let us infer the surface potential. The slope of this potential at the surface gives a measure of the charge bound. 

Nonlinear optical process, like multi-photon absorpticHi, can be understood through analyses of the induced electric polarization. When an electric field is applied to a medium, charges bound in each molecule will react to the applied field and will execute perturbed motions, changing the molecular charge density of the... 

Here nsi is the density of species i in the solution next to the solid surface, and n j = o< is the known density of species i in the bulk far from the surface, where = 0. For each species, n t can be obtained from t/tj, the value of fr at the solid surface, using the Boltzmann equation (2-41). Thus, Eq. (2-44) can be used to link the surface potential to the density a of charges bound to the solid surface. 

The above provides an explanation for a role of ionic charges bound to the polymer network in the gel transition, i.e., how the charge density affects the volume of an ionic gel at a transition as well as the transition threshold. However, the partially ionized PAAm gel is not a very good sample for discussing the effect of charge density on the reduced temperature as the transition threshold. Acetone acts as a poor solvent for PAAm or its hy-... 

This is displacement of positive ions with respect to negative ions. To clarify the division between electronic and ionic polarization electronic polarization is the displacement of the electron cloud with respect to the nucleus ionic polarization is the displacement of ions relative to each other. The hydrated sheath around an ion at rest is symmetrical (not really at rest, everything is bumping around at room temperature, we are talking statistically). When current flows, the sheath will lag behind the migrating ion, and the sheath is no longer symmetrical to the ion, cf. the Wien effect (Section 8.4.1). This is local polarization of charges bound to each other. 

With dry skin, the admittance may be less than 1 pS/cm at 1 Hz. A typical admittance of more than 100 pS/cm is possible when the SC is saturated by electrolytes and water. The conductivity is very dependent on water content and is believed to be caused, for example, by protons (H" ") and charged, bound proteins that contribute only to AC admittance. 

In analytical applications of ion exchange chromatography two aspects of retention are of main interest (1) How does the retention factor vary with the concentration of eluent salt (2) What factors determine the selectivity between different analyte ions From a theoretical point of view, it is clear that with increasing concentration of electrolyte in the external solution, the magnitude of the electrostatic potential in the resin phase decreases. The reason is that the added electrolyte ions partly shield the charges bound to the resin phase. For analyte counterions this implies that their sorption to the resin phase decreases giving a lower retention factor. 

Obviously, the physical meaning of the capacitance can be complex, inasmuch as it involves the contributions from both the free charge and the charge bound in the ion pairs, ff there is no ion transfer across the interface, = Wx- = + = y-the system behaves as an ideally polarizable interface in a sense that the interfacial state can be controlled by the charge suppUed from outside. In particular, in the absence of the ion pairs, the capacitance is given by ... 

Lawless, P.A. (1996). Particle Charging Bounds, Symmetry Relations, and an Analytic Charging Rate Model for the Continuum Regime. J. Aerosol Sci., Vol. 27, pp. 191-215. 

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