Charge neutralization processes

Liquid carbon dioxide is decomposed efficiently by ionizing radiation79. The decreased radiation stability of the liquid phase compared to the gas phase has been attributed to the much smaller contribution of ion-molecule reactions to radiolysis in the condensed phase, where an efficient geminate charge neutralization process is likely to minimize the occurrence of such processes. Ion-molecule reactions are probably responsible for the rapid reoxidation observed in the gas phase. The yields of CO, 02 and 03 from the y-radiolysis of liquid C02 can be... 

Ionic recombination is a general term used to describe the charge neutralization processes which can occur when a positive ion and a negative ion interact producing neutral particles. Three distinct mechanisms have been characterised according to how the energy released in the interaction is dispersed, as in the case of electron-ion recombination. They are... 

Research done in the author s laboratory indicates that the processes described nearly, but not completely, neutralize the metal ion s charge. Polar water molecules are added as adducts around the chelate, the ion association complex or the micelle as necessary to complete the charge neutralization process as shown in the diagram at the top of the next page. This produces a neutral molecule that is hydrophilic and tends to stay in the aqueous layer. If a suitable organic liquid is added, these molecules usually can... 

An alternative process involving fragmentation of the parent positive ion cannot be excluded, tert-Butyl radicals may be formed by the charge neutralization process. 

How are those radicals formed In a liquid that is exposed to ionizing radiation the formation of radicals is preceded by a number of rather complex steps. Basically, in the primary steps that follow the absorption of ionizing radiation the molecules of the absorbent become ionized or electronically excited. In nonpolar liquids such as alkanes, the charge neutralization processes are fast and therefore the lifetime of the charged species, molecular cations (RH ") and electrons, is very short. The directly formed excited molecules (RH ) or those that are created in the neutralization processes (RH ) can lose their energy in processes such as radiative and nonradiative conversion to the ground state, collisional deactivation, etc. These processes do not result in a chemical change in the system. Alternatively, these excited molecules can dissociate into molecular products and free radicals. This latter chain of events, that leads to the formation of radicals, is summarized by reactions 2-11. 

The positive charge should reside on a complex entity, and there is no ready means for assessing the products of the neutralization process. Although we know that neutralization must yield 3.8 intermediates/100 e.v., there is no chemical evidence for their contribution to the product distribution. This cannot be interpreted by neutralization yielding predominantly hydrogen atoms, ethyl radicals, or methyl radicals. One can quantitatively account for these intermediates on the basis of the distribution of primary species and second- and third-order ion-molecule reactions (36). 

There are basically two kinds of neutralization processes for the cation, reaction with the electron and with a negative ion. In each case, it may be assumed that neutralization will occur with the parent or fragment ion of lowest energy. It is believed that the various degradation processes for the cation-fragmentation, ion-molecule reaction, and so forth—are much faster than the neutralization process. In addition, one considers charge transfer, without decomposition, from the cation formally as a neutralization of that species. To effect that, of course, one... 

The broad nature of the current peaks in the voltammogram of conducting polymers such as poly pyrrole has been interpreted in a number of w one of which was to attribute it to the movement of anions across the polymei, electrolyte interface, a vital process if the overall charge neutrality of the film is to be maintained. The participation of the electrolyte in the electrochemistry of the polymer film is easily seen by comparing the response of polypyrrole in a variety of different electrolytes (see Figure 3.74). 

The process of chelation was discussed in Chapter 3. To form uncharged chelates which can readily be extracted into organic solvents the reagent must behave as a weak acid whose anion can participate in charge neutralization and contain hydrophobic groups to reduce the aqueous solubility of the complex. The formation and extraction of the neutral chelate is best considered stepwise as several equilibria are... 

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