Photogeneration of ions

The main achievement of UT was the incorporation of a distribution of ionization products m(r,t). The latter was not inherent to the original DET and was introduced only a posteriori in IET. The UT kinetic equation for this quantity, (3.290), is actually a symbiosis of Eq. (3.216) for the remote RIP recombination and the pumping term (3.288) responsible for their accumulation. This combination allows tracing the photogeneration of ions after 5-pulse excitation and their subsequent recombination and separation. 

Cationic cure mechanisms are an alternative approach to uv curing. This involves the photogeneration of ions, which initiate ionic polymerization. This process is not subject to oxygen inhibition, as are some of the free radical mechanisms. Cationic cure mechanisms generally also provide less shrinkage and improved adhesion. The disadvantages are that the photoinitiators are sensitive to moisture and other basic materials. The acidic species can also promote corrosion. As a result, the vast majority of uv formulations are acrylate-based and cure by a free radical mechanism. 

Considering the difficulties in measuring simple ion-transfer kinetics, photogeneration of ions close to the interface and observation of the photocurrent associated with their transfer was proposed. In this way, the interfadal polarization is kept quasi-constant, and the photocurrent does not suffer from the RC lime constant of the interface. This concept was pioneered by Kotov and Kuzmin that published a series of papers on the subject [143-146]. Two kinds of photochani-cal systems were used protoporphyrin (excitation 540-580 nm) quenched by quinones, and quinones (excitation 313-365 nm) quenched by telraphenylborale. Similarly, Samec et al. have studied photoinduced ion-transfer reactions nsing tetra-arylborate and tetra-arylarsonium as the chromophore, thereby generating the more hydrophilic bridged tetra-aryl intermediate [147,148]. 

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