Charged species INDEX

The dielectric constant is a measure of the ease with which charged species in a material can be displaced to form dipoles. There are four primary mechanisms of polarization in glasses (13) electronic, atomic, orientational, and interfacial polarization. Electronic polarization arises from the displacement of electron clouds and is important at optical (ultraviolet) frequencies. At optical frequencies, the dielectric constant of a glass is related to the refractive index k =. Atomic polarization occurs at infrared frequencies and involves the displacement of positive and negative ions. 

The interface is in contact with two bulk phases, the metal electrode (index m ) and the solution (index s). Formally, we consider the metal to be composed of metal atoms M, metal ions Mz+, and electrons e " these particles are present both in the electrode and the interface, but not in the solution. On the other hand, certain cations and anions and neutral species occur both in the solution and the interface. Since the electrode is ideally polarizable, no charged species can pass through the interface. 

The calculation of the activity coefficient is separately done for positively (index i) and negatively (index j) charged species applying Eq. 22. In this example the calculation of the activity coefficients for cations is shown, which can be analogously done for anions just exchanging the corresponding indices. 

We next adapt the arguments of Section 3.5 to the present situation by defining the mole fraction for the ith positively charged species in solution by xi+ - ni+/ (s) /sns = i i+/Z(s),/8ms-Here a new notation has been adopted The index s runs over all distinct chemical compounds added to the aqueous phase, not over the ionic species i present in the solution the dissociation process of these compounds in water is attended to by insertion of the sum vs = i/s+ + i/s. Here i/s+ or i/s are the number of cations or anions derived from the complete dissociation of the sth species M +A into the i/s+ positive and vs- negative ions, Mz+ and Az. Thus, each mole of the compound M +A yields (i/+ + vJ) == v moles of ions in solution. We assume that the solvent (s - 1) remains un-ionized and that complete solute ionization occurs the case of incomplete ionization is handled later. For nonionic species t/s - 1 moreover, for the solvent, mi - 1000/Mi see Eq. (3.5.2). Thus,... 

Here a(r) are ionic densities, where the indexes a and A are summed over aU the charged species. We shall by pm (r) denote the collective density of all monomers, neutral as well as charged. Note that only the second monomer along the cationic chain is charged, with a density denoted n r). The first term in eq.(43) is just the mean-field electrostatic interaction between ions. The second term describes the interactions between the ions and the uniform surface charge. We note that is zero for the bulk phase IL. 

Here, for completely ionized solutes we define the mole fraction for the ith positively charged species in solution by where the index j runs over aU distinct chemical compounds added... 

Here the index "o/w" indicates the presence of L in both organic and aqueous phases. For example, for Zr +, U4+ and Pu4+ an ethylenediaminetetraacetic acid (EDTA, H4edta), which forms the neutral complexes [M(lV)edta]° might be a good choice, while for Am and Ln < EDTA is undesirable, but the dialkyl ester of diethylenetriaminepentaacetic acid (DTPA, Hsdtpa) - HsR2dtpa is expected to form the same zero charged species [Ln(R2dtpa)]°, where R indicated some alkyl. 

Photorefractivity is a property exhibited by some materials in which the redistribution in space of photogenerated charges will induce a nonuniform electric space-charge field which can, in turn, affect the refractive index of the material. In a new material the active species is a highly efficient cyclopalladated molecule97,98 shown in Figure 5. The palladium-bonded azobenzene molecule is conformationally locked, and gratings derived from cis—trans isomerizations can be safely excluded. 

Aromatic substitution reactions are often complicated and multistep processes. A correlation, however, in many cases can be found between the charged attacking species and the electron density distribution in the molecule attacked during electrophilic and nucleoph c substitution. No such correlation is expected in radical substitution where the attacking particles are neutral, rather a correlation between the reactivities of separate bonds and a free valency index of the bond order. This allows the prediction of the most reactive bonds. Such an approach has been used by researchers who applied quantum calculations to estimate the reactivities of the isomeric thienothiophenes and to compare them with thiophene or naphthalene. " Until recently quantum methods for studying reactivities of aromatics and heteroaromatics were developed mainly in the r-electron approximation (see, for example, Streitwieser and Zahradnik ). The M orbitals of a sulfur atom were shown not to contribute substantially to calculations of dipole moments, polarographic reduction potentials, spin-density distribution, ... 

Let us discuss an L matrix transformation for isothermal and isobaric atomic fluxes when there is one additional electronic species present. We start with the flux equations in which the index j denotes the atomic species and e denotes the electric charge carriers (eg., electrons). 

---