Light-induced decomposition

Muradov, N.Z., Bazhutin, Yu., Bezuglaya, A., and Rustamov, M., Visible light induced decomposition of hydrogen sulfide in aqueous solutions using cadmium sulfide, ]. Phys. Chem., 54, 2563,1982 (in Russian). 

Figure 7.9 Schematic representation of visible light-induced decomposition of water using RuOj and Pt as redox catalysts codeposited on colloidal Ti02-(Following Gratzel, 1981.)...

Lack of stereospecificity, extensive formation of olefinic products, and extensive tar formation limit the thermal decomposition of pyrazolines as a route to cyclopropanes.182 263 Light-induced decomposition of stereoisomeric pyrazolines establishes a method for the formation of cyclopropanes stereospecifically.222 Photolysis of 3-carbomethoxy-cis-3,4-dimethyl-l-pyrazoline (CCLI) produced cis-l,2-dimethylcycIopropane-l-carboxylate (CCLII) and without olefinic formation. Furthermore, irradiation of 3-carbomethoxy-trans-3,4-dimethyl-l-pyrazoline (CCLIII) gave [Pg.123]

Sattar, A., de Man, J.M., Alexander, J.C. 1977a. Wavelength effects on light-induced decomposition of vitamin A and (3-carotene in solutions and milk fat. Can. Inst. Food Sci. Technol. J. 10, 56—64. 

One very interesting new application of Lewis acids in curing epoxy adhesives has appeared within the last 25 years. The Lewis acid initiator for the cationic polymerization is formed by the heat or ultraviolet light-induced decomposition of Lewis acid Lewis base salts. Several patents by Crivello and coworkers43 47 describe compounds containing... 

An important practical objective for studying the photophysics of the silver halides is to learn to control the light-induced decomposition sequence leading to the formation of the photographic latent image. Structural imperfections have been found to play a critical role in these events through their interactions with excitons and free carriers. 

Fig. 8.1a, b. Schemes for the visible light-induced decomposition of water a colloidal redox catalysts are present as separated entities. b Bifunctional redox catalyst Ru02 and Pt are codeposited on the colloidal Ti02 carrier particle... 

Fig. 8.10. a Light and dark cycles in the UV-light induced decomposition of water. 24 ml solutions containing 400 mg l l Ti02 as well as 40 mg l-1 Pt and 0.1% Ru02 (per weight of Ti02 codeposited were irradiated with a 450 W-Xe lamp, b Band model to explain the processes induced by band gap irradiation... 

Copper-catalyzed " or light-induced decompositions of diazoalkanes... 

Cross-linking of a linear polymer backbone by the light-induced decomposition of a photosensitizer to generate active species (e.g., cyclized rubber with azide type photosensitizer). 

Note 1. Commercial chloroform is stabilized with ethanol to suppress light-induced decomposition to toxic phosgene. Such stabilizer is detrimental to imprinting because of its good hydrogen bonding properties. Ethanol-free chloroform can be obtained by fractional distillation from the commercial product. For the same reason, before use the chloroform must be dried on 4.5 A molecular traps to eliminate any trace of water. 

The initiating free radical can come from many sources. Thermal decompositions of compounds with azo and peroxy groups are common sources of such radicals. The radicals can also come from redox reactions or through various light-induced decompositions. Ionizing radiation can also be used to form initiating radicals. 

Reproduction technology utilizes the light-induced decomposition of azoketones in the so-called negative process. Carbenes occur as intermediates, which add onto ketene derivatives these then cross-link, for example, with poly(p-aminostyrene) ... 

Huntzicker et al. [34] have shown the photochemical reactivity of tetraethyllead and tetramethyllead, finding that there is a light induced decomposition in the atmosphere. These organic compounds are less volatile than gasoline, but small amounts may be emitted to the atmosphere by evaporation from fuel storage and transportation systems. 

In the course of prolonged service life, UV absorbers are losing their absorption behavior, for example, by reaction of their phenolic function with peroxy radicals. Besides chemical reactions, simple depletion of such compounds can be another reason for the loss of their efficiency. For example, benzophenone-type UV absorbers are described to deplete from polyethylene-vinylacetate copolymer (EVA)-based encapsulants used in solar cells.In order to avoid such deficits, attempts have been made to develop UV absorbers incorporated in polymer stmctures. Manifold experimental results indicate that the loss of UV absorbers is initiated by light-induced decomposition reactions rather by migration from polymer substrates. 

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