Photochemistry applied

V. Vuitton, J.-F. Doussin, Y. Benilan, F. Raulin, M.-C. Gazeau, Experimental and theoretical study of hydrocarbon photochemistry applied to Titan stratosphere. Icarus 185(1), 287-300 (2006)... 

Abstract This chapter introduces the supramolecular photochemistry, i.e. photochemistry applied to supramolecular systems, and discusses the thermodynamic and kinetic aspects of photoinduced energy and electron transfer processes both between molecules and within supramolecular systems. In the case of electron transfer processes, Marcus theory is presented as well as quantum mechanical theory. For energy transfer processes, coulombic and exchange mechanisms are illustrated and the role of the bridge in supramolecular structures is discussed. 

Allen, R. S. (ed.), Developments in Polymer Photochemistry , Applied Science, London, vols. 1 and 2, 1980-1982. 

To use direct dynamics for the study of non-adiabatic systems it is necessary to be able to efficiently and accurately calculate electronic wave functions for excited states. In recent years, density functional theory (DFT) has been gaining ground over traditional Hartree-Fock based SCF calculations for the treatment of the ground state of large molecules. Recent advances mean that so-called time-dependent DFT methods are now also being applied to excited states. Even so, at present, the best general methods for the treatment of the photochemistry of polyatomic organic molecules are MCSCF methods, of which the CASSCF method is particularly powerful. 

There is a multiplicity of pathways for thermal dediazoniations. An analogous situation is to be expected for photochemical dediazoniations. Based on the general experience that light-sensitive reactions often involve free radical intermediates, it was commonly assumed that all photolytic dediazoniations are free radical reactions. Horner and Stohr s results (1952), mentioned above, could lead to such a conclusion. More sophisticated methods of photochemistry also began to be applied to investigations on arenediazonium salts, e. g., the study of photolyses by irradiation at an absorption maximum of the diazonium ion using broad-band or monochromatic radiation. This technique was advocated by Sukigahara and Kikuchi (1967 a, 1967 b,... 

The primary reason for studying aqueous plutonium photochemistry has been the scientific value. No other aqueous metal system has such a wide range of chemistry four oxidation states can co-exist (III, IV, V, and VI), and the Pu(IV) state can form polymer material. Cation charges on these species range from 1 to 4, and there are molecular as well as metallic ions. A wide variety of anion and chelating complex chemistry applies to the respective oxidation states. Finally, all of this aqueous plutonium chemistry could be affected by the absorption of light, and perhaps new plutonium species could be discovered by photon excitation. 

Hiroshi Fukumura received his M.Sc and Ph.D. degrees from Tohoku University, Japan. He studied biocompatibility of polymers in the Government Industrial Research Institute of Osaka from 1983 to 1988. He became an assistant professor at Kyoto Institute of Technology in 1988, and then moved to the Department of Applied Physics, Osaka University in 1991, where he worked on the mechanism of laser ablation and laser molecular implantation. Since 1998, he is a professor in the Department of Chemistry at Tohoku University. He received the Award of the Japanese Photochemistry Association in 2000, and the Award for Creative Work from The Chemical Society Japan in 2005. His main research interest is the physical chemistry of organic molecules including polymeric materials studied with various kinds of time-resolved techniques and scanning probe microscopes. 

In studies of this kind, methods developed in radiation chemistry and photochemistry are often applied The methods of pulse radiolysis and flash photolysis allow one to investigate the mechanism of reactions in which free radicals, electrons and positive holes are the intermediates. In order to understand the mechanisms of processes that occur on colloidal particles it is important to know how free radicals... 

McKellar, J.F., and Allen, N.S., "Photochemistry of Man-Made Polymers",Applied Science Publishers,London, 1979,p.10. 

Generally the first thing to be done in preparation for the photochemical study of a compound is to determine the visible and ultraviolet absorption spectrum of the compound. Besides furnishing information concerning the nature of the excited state potentially involved in the photochemistry (see Section 1.4), the absorption spectrum furnishes information of a more applied nature as to the wavelength range in which the material absorbs and its molar absorptivity e. From this information it is possible to decide what type of light source to use for the irradiation, what solvents can be used to... 

JF McKellar, NS Allen. Photochemistry of Man-Made Polymers. London Applied Science Publishers, 1979. 

The literature of diene and polyene photochemistry provides many cases of synthetically useful reactions. As a result, certain arbitrary decisions have been made regarding what is covered in this chapter. For example, intramolecular [2 + 2]-photocycloaddition reactions of a, >-dienes can be formally included under the general rubric of diene photochemistry. However, we have chosen to restrict our discussion to dienes and polyenes which constitute a self-contained chromophore, viz. conjugated, cross-conjugated and 1,4-diene systems. Likewise, arene-olefin photocycloadditions will not be considered. These two broad classes of photoreactions have been applied extensively in synthesis, and have been the subject of recent reviews3,4. 

The purpose of the present article is to review comprehensively those photochemical reactions of carbohydrates for which product structures have been established, and to apply current mechanistic reasoning to the understanding of these reactions. Two reviews of carbohydrate photochemistry already exist. The first1 2 was published in this Series in 1963, prior to the considerable recent growth in this field, and the second was a brief summary published in the Japanese literature in 1973. 

Porter G (1978) Pure and applied photochemistry. Pure Appl Chem 50 263-271... 

The rationalization of mass spectrometric investigations of nitro compounds has benefited significantly from numerous studies applying techniques adopted from photochemistry, such as photodissociation, photoionization and photoelectron photoion coincidence spectroscopy. 

The accumulation of data on these metallic complexes in the area of solar energy conversion and storage [2], has allowed a rationalisation of the photochemistry of these compounds [3,4], Therefore they can now be easily applied in the context of DNA biochemistry. 

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