Atmospheric photochemistry

F. C. Krebs, J. E. Carle, N. Cruys-Bagger, M. Andersen, M. R. Lil-liedal, M. A. Hammond, and S. Hvidt. Lifetimes of organic photo-voltaics Photochemistry, atmosphere effects and barrier layers in ITO-... 

Krebs, F.C., Carl, J.E., Cruys-Bagger, N., Andersen, M., Lilliedal, M.R., Hammond, M.A., Hvidt, S., 2005. Lifetimes of organic photovoltaics photochemistry, atmosphere effects and barrier layers in ITO-MEHPPViPCBM-aluminium devices. Sol. Energ. Mat Sol. Cells 86,499-516. 

Chemistry chemical engineering bioengineering physics physical chemistry organic chemistry biochemistry molecular biology electrochemistry analytical chemistry photochemistry atmospheric chemistry agricultural chemistry industrial ecology toxicology. 

Domine, R, Albert, M., HuthweUcer, T., Jacobi, H.-W., Kokhanovsky, A.A., Lehning, M., Picard, G., Simpson, W.R. 2008. Snow physics as relevant to snow photochemistry. Atmospheric Chemistry and Physics 8, 171-208. 

Air pollution meteorology came of age and, by 1980, mathematical models of the pollution of the atmosphere were being energetically developed. A start had been made in elucidating the photochemistry of air pollution. Air quality monitoring systems became operational throughout the world. A wide variety of measuring instruments became available. 

The high concentration of oxygen in the atmosphere plays a central role in the photochemistry and chemical reactivity of the atmosphere. Atmospheric oxygen also defines the oxidation reduction potential of surface waters saturated with oxygen. The presence of oxygen defines the speciation of many other aquatic species in surface waters. 

Photochemistry plays a significant role in nitrogen s atmospheric chemistry by producing reactive species (such as OH radicals). These radicals are primarily responsible for all atmospheric oxidations. However, since the photochemistry of the atmosphere is quite complex, it will not be dealt with in detail here. For an in-depth review on tropospheric photochemistry, the reader is referred to Logan et al. (1981), Finlayson-Pitts and Pitts (1986), Crutzen and Gidel (1983) or Crutzen (1988). 

Models of chemical reactions of trace pollutants in groundwater must be based on experimental analysis of the kinetics of possible pollutant interactions with earth materials, much the same as smog chamber studies considered atmospheric photochemistry. Fundamental research could determine the surface chemistry of soil components and processes such as adsorption and desorption, pore diffusion, and biodegradation of contaminants. Hydrodynamic pollutant transport models should be upgraded to take into account chemical reactions at surfaces. 

The photochemistry of Titan s atmosphere can be summarized as follows the unsaturated compounds are formed from HCN and C2H2, which is derived from CH4. Methane decomposition leads to further ethane formation. 

Yi-Jehng Kuan el al. (2004). Searches for interstellar molecules of potential prebiotic importance. Advances in Space Research 33 31-39 Yung Y., Allen M. and Pinto J. (1984). Photochemistry of the atmosphere of Titan comparison between model and observations. Astronomy Astrophysics Supplement... 

Extensive research has been conducted into the atmospheric chemistry of organic chemicals because of air quality concerns. Recently, Atkinson and coworkers (1984, 1985, 1987, 1988, 1989, 1990, 1991), Altshuller (1980, 1991) and Sabljic and Glisten (1990) have reviewed the photochemistry of many organic chemicals of environmental interest for their gas phase reactions with hydroxyl radicals (OH), ozone (03) and nitrate radicals (N03) and have provided detailed information on reaction rate constants and experimental conditions, which allowed the estimation of atmospheric lifetimes. Klopffer (1991) has estimated the atmospheric lifetimes for the reaction with OH radicals to range from 1 hour to 130 years, based on these reaction rate constants and an assumed constant concentration of OH... 

Dilling, W.L., Bredweg, C.J., Tefertiller, N.B. (1976) Organic photochemistry. Simulated atmospheric photodecomposition rate of methylene chloride, 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, and other compounds. Environ. Sci. Technol. 10, 351-356. 

Kopczynski SL, Lonneman WA, Sutterfield FD, et al. 1972. Photochemistry of atmospheric samples in Los Angeles. Environmental Science Technology 6(4) 342-347. 

The decompositions of C302, CO, C02, CS2, COS, CSe2 and COSe are dealt with in this section. Apart from carbon suboxide, this is a group of stable, un-reactive compounds. Considerable emphasis has been placed on the investigation of the photolytic decompositions of some of these compounds which are thought to provide useful sources of atoms (C, O, S and Se) and free radicals (C20). The photochemistry of carbon dioxide has particular relevance to the chemistry of planetary atmospheres, although to date the mechanism of C02 photolysis remains obscure. 

Photochemically-generated radicals are encountered as reactive intermediates in many important systems, being a major driving force in the photochemistry of ozone in the upper atmosphere (stratosphere) and the polluted lower atmosphere (troposphere). The photochemistry of organic carbonyl compounds is dominated by radical chemistry (Chapter 9). Photoinitiators are used to form radicals used as intermediates in the chain growth and cross-linking of polymers involved in the production of electronic circuitry and in dental treatment. 

The photochemistry of the polluted atmosphere is exceedingly complex. Even if one considers only a single hydrocarbon pollutant, with typical concentrations of nitrogen oxides, carbon monoxide, water vapor, and other trace components of air, several hundred chemical reactions are involved in a realistic assessment of the chemical evolution of such a system. The actual urban atmosphere contains not just one but hundreds of different hydrocarbons, each with its own reactivity and oxidation products. 

Taking into account the requirements listed in Section A, it would be desirable if the reactants A and B be compounds which are very cheap and readily available. Naturally, the constituents of the atmosphere and liquid water fill this requirement admirably. Table 1 lists most of the endergonic fuel generation reactions which involve N2, CO2 and H2O as reactants including the reaction of photosynthesis. It is significant that the potential difference AE , which is the potential stored per electron transferred, is between 1.02 V and 1.48 V for all of the reactions in Table 1. Thus, the energy requirements for the photochemistry are about the same for each of these reactions. We immediately see that the reaction of photosynthesis (reaction 9 of Table 1) is in troiable for one photosystem because is known to be 700 nm. The imp-... 

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