Sunlight spectrum

Efficiently use the entire sunlight spectrum to be competitive with routes based on photovoltaics coupled with electrochemically driven catalysis. 

The sunlight spectrum (Fig. 10.2) is a standard for photographic work. The primary colors are red, green, blue (RGB). These can be combined to yield all colors. 

M. Oelgemoeller, C. Christian, J. Ortncr. J. Mattay, C. Schiel, and E. Zimmermann, Green photochemistry with moderately concentrated sunlight. Spectrum 18, 28-33 (2005)... 

This experiment also shows the eflFects of slow convection mixing vs. circulating the solution rapidly. Light of 290 nm wavelength, the lower limit of the sunlight spectrum 11), can penetrate a 4.14 X 10 M picloram... 

Although exact values depend upon the specific compound under consideration, approximate values for the homolytic dissociation energies of common bonds have been tabulated (26, 27). For example, homolytic cleavage of the C-H bonds in benzene requires 104 kcal/mole H-CH2OH, 92 phenyl OCl, about 80 H-OH, 118 and HO-OH, 48 kcal/mole. Figure 1 shows that while the sunlight spectrum (B) is ex-... 

While the availability of hydrogen atoms and/or hydride ions for photoreductions in organic solvents is apparent, the usual presence of reduced products from the photolysis of pesticides in aqueous media remains anomalous. Energy for the homolytic cleavage of water (about 118 kcal/mole) probably would not be derived from the sunlight spectrum, and the unlikely backward ionic dissociation of water to form hydride and hydroxonium (HO" ) ions never has been demonstrated. 

Figure 26 Volumetric productivity of a photobioreactor Tx as a function of biomass concentration Cx according to Blackman red (dark gray in the print version) lines) and Jassby and Platt blue dark gray in the print version) lines). Solid lines represent resuits for /pi,(0) = 0.75 X 10 molph m s - dashed lines represent resuits for /ph(0) = 1.5 x 1 molph m s Photobioreactor d=0.03 m. Parameter values are based on high-light acclimated Chlorella sorokiniana and a sunlight spectrum Ox=3.33 m moixfor sunlight Vs/ph,m = 0.10 mols molph <7s,m = 1-25 x 10 mols moix s V x/s=0.625 moix mol i ms=3.0 x 10 mols moix" s .

These compounds are often still referred to as the classical absorbed system because they were originally designed to absorb the ultraviolet portion of the sunlight spectrum in the range 290-400 nm, i.e. the region which is detrimental to most polymer systems. There are three major types of absorbers, namely the 2-hydroxybenzophenones, 2-hydroxy-phenylbenzotriazoles, and 2-hydroxyphenyl-S-triazines (see Structures 1 to 3). The modes of action of these stabilizers are now classified into three distinct types [1-3] ... 

Figure 6.2. Energy distribution of the sunlight spectrum. A. Monochromatic mercury lamp at 254 nm. B. Black light lamp. (From Crosby, 1972.) American Chemical Society. Reprinted with permission.

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