THE BROMINE-SENSITIZED DECOMPOSITION OF CHLORINE MONOXIDE IN GREEN LIGHT

1937 ◽  
Vol 15b (3) ◽  
pp. 113-123 ◽  
Author(s):  
A. G. Brown ◽  
J. W. T. Spinks
Keyword(s):  
Quantum Yield ◽  
Chlorine Dioxide ◽  
Wave Length ◽  
Green Light ◽  
Dark Reaction ◽  
Chlorine Monoxide

Chlorine monoxide undergoes a bromine-sensitized decomposition in light of wave-length 5460 A. The reaction involves short chains and is accompanied by an appreciable dark reaction. The quantum yield is 4.3 at 19 °C. A decrease in pressure occurring near the end of the reaction has been shown to be a photochemical effect, and it is due probably to the bromine-sensitized decomposition of chlorine dioxide formed during the combined light and dark reactions.A mechanism similar to that described by Finkelnburg, Schumacher and Stieger for the unsensitized reaction appears to account for most of the observations.

THE PHOTODECOMPOSITION OF CHLORINE DIOXIDE IN CARBON TETRACHLORIDE SOLUTION

1937 ◽  
Vol 15b (12) ◽  
pp. 499-524 ◽  
Author(s):  
J. W. T. Spinks ◽  
H. Taube
Keyword(s):  
Thermal Decomposition ◽  
Carbon Tetrachloride ◽  
Quantum Yield ◽  
Light Intensity ◽  
Quantum Efficiency ◽  
Chlorine Dioxide ◽  
Concentration Effects ◽  
Low Light ◽  
Carbon Tetrachloride Solution ◽  
Chlorine Monoxide

Insolation of carbon tetrachloride solutions of chlorine dioxide initiates a thermal decomposition, the magnitude of which may exceed that for the photoreaction with low light intensity. This thermal decomposition is inhibited by keeping the solutions at 3 °C. or by adding water.In contradiction to the findings of other investigators, it is found that chlorine and oxygen are not the only products of photodecomposition. As products of the photodecomposition of chlorine dioxide at the wave-lengths 3650 and 4360 Å, the oxides Cl2O, Cl2O6, and Cl2O7 as well as chlorine and oxygen appear. The quantum efficiency at λ 3650 Å is 2, and at 4360 Å, 1.In the unsensitized decomposition, concentration effects are observed which are greatly decreased when the solutions are stirred.In the bromine sensitized decomposition with 5460 Å, there is less chlorine monoxide but relatively as much Cl2O6 and Cl2O7 formed as in the unsensitized reaction.In the sensitized decomposition the quantum yield is independent of the concentration of chlorine dioxide, but depends on the light intensity. The observed quantum yield for the sensitized reaction is 0.2 to 0.3.Mechanisms for the photo-reactions have been proposed.

DICHLORINE HEXOXIDE

1938 ◽  
Vol 16b (11) ◽  
pp. 382-389 ◽  
Author(s):  
M. H. Kalina ◽  
J. W. T. Spinks
Keyword(s):  
Molecular Weight ◽  
Carbon Tetrachloride ◽  
Quantum Yield ◽  
Physical Properties ◽  
Extinction Coefficient ◽  
Quantitative Estimation ◽  
Wave Length ◽  
Colorimetric Method ◽  
Green Light ◽  
Carbon Tetrachloride Solution

Some chemical and physical properties of dichlorine hexoxide are described and attention is drawn to its dangerous property of exploding violently on contact with organic substances.The extinction coefficient of solutions of dichlorine hexoxide in carbon tetrachloride solution for a wave-length of 5460 Å has been measured and found to be 2.4, which is very much less than that of liquid dichlorine hexoxide for the same wave-length. A colorimetric method is described for the quantitative estimation of dichlorine hexoxide in solutions. The molecular weight of dichlorine hexoxide in carbon tetrachloride solution has been redetermined, and it confirms the formula Cl2O6.Solutions of dichlorine hexoxide in carbon tetrachloride are decomposed photochemically by green light. Gaseous chlorine trioxide (ClO3) is decomposed photochemically by λ3650. Its decomposition is photosensitized by chlorine and bromine, the quantum yield in the chlorine sensitized reaction being about 1.

scholarly journals High Emission Quantum Yield Tb3+ -Activated Organic-Inorganic Hybrids for UV-Down-Shifting Green Light-Emitting Diodes

2020 ◽  
Vol 2020 (18) ◽  
pp. 1736-1742
Author(s):  
Sandra F. H. Correia ◽  
Ricardo L. Fernandes ◽  
Lianshe Fu ◽  
Mariela M. Nolasco ◽  
Luís D. Carlos ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Light Emitting Diodes ◽  
Green Light ◽  
Light Emitting ◽  
High Emission ◽  
Emission Quantum Yield

scholarly journals THE PHOTOSYNTHETIC EFFICIENCY OF PHYCOCYANIN IN CHROOCOCCUS, AND THE PROBLEM OF CAROTENOID PARTICIPATION IN PHOTOSYNTHESIS

1942 ◽  
Vol 25 (4) ◽  
pp. 579-595 ◽  
Author(s):  
Robert Emerson ◽  
Charlton M. Lewis
Keyword(s):  
Quantum Yield ◽  
Absorption Spectra ◽  
Photosynthetic Efficiency ◽  
High Efficiency ◽  
Wave Length ◽  
Visible Spectrum ◽  
Living Cells ◽  
Reasonable Doubt ◽  
Carotenoid Pigments ◽  
Relative Absorption

The absorption spectra of the principal pigment components extracted from Chroococcus cells have been measured, and their sum compared with the absorption of a suspension of living cells. The agreement was sufficiently close so that it was concluded the absorption spectra of the extracted and separated pigment components could be used to obtain estimates of the relative absorption of the various components in the living cells. The quantum yield of Chroococcus photosynthesis was measured at a succession of wave lengths throughout the visible spectrum, and the dependence of yield on wave length was compared with the proportions of light absorbed by the pigment components. This comparison showed beyond reasonable doubt that the light absorbed by phycocyanin is utilized in photosynthesis with an efficiency approximately equal to that of the light absorbed by chlorophyll. The light absorbed by the carotenoid pigments of Chroococcus seems for the most part to be unavailable for photosynthesis. The results leave open the possibility that light absorbed by the carotenoids is active in photosynthesis, but with an efficiency considerably lower than that of chlorophyll and phycocyanin. It is also possible that the light absorbed by one or a few of the several carotenoid components is utilized with a high efficiency, while the light absorbed by most of the components is lost for photosynthesis.

CONDITIONS FOR THE PHOTOCHEMICAL NITRATION OF BENZENE

1965 ◽  
Vol 43 (6) ◽  
pp. 1714-1719 ◽  
Author(s):  
David L. Bunbury
Keyword(s):  
Liquid Phase ◽  
Quantum Yield ◽  
Nitrogen Dioxide ◽  
Gas Phase ◽  
Dark Reaction ◽  
Gas Phases

The reaction of benzene and nitrogen dioxide to produce nitrobenzene has been studied in the liquid and gas phases, in the dark, and with irradiation by light of 439 mμ and of 366 mμ. The concentration of NO2 in the liquid was varied from 0.08 to 1.6 moles/1 and in the gas from 0.0035 to 0.053 moles/1. No nitrobenzene was produced under any conditions in the liquid phase. Nitrobenzene is produced in the gas phase at high NO2 concentrations with irradiation by 366 mμ light. The quantum yield is 0.2. At 439 mμ the quantum yield is not more than 0.02. There is a very small dark reaction. As the concentration of NO2 in the gas is reduced the yield of nitrobenzene falls off very rapidly and is zero at the lowest concentration used, both in dark and light.

PHOTOCATALYTIC ACTIVITY OF NITROGEN AND FLUORINE CO-DOPED TITANIUM DIOXIDE PREPARED USING OF VARIOUS PH SOLUTIONS

2010 ◽  
Vol 24 (15n16) ◽  
pp. 3242-3247 ◽  
Author(s):  
MASAHIRO KATOH ◽  
AKIHIRO IMAYAMA ◽  
NARISUKE MORI ◽  
TOSHIHIDE HORIKAWA ◽  
TAHEI TOMIDA
Keyword(s):  
Methylene Blue ◽  
Photocatalytic Activity ◽  
Visible Light ◽  
Uv Light ◽  
Anatase Phase ◽  
Wave Length ◽  
Green Light ◽  
Light Irradiation ◽  
Mixed Solution ◽  
Co Doped

Introducing different atoms into TiO 2 crystal lattice is a famous method to improve photocatalytic activity of TiO 2 under visible-light irradiation. In this paper, Nitrogen ( N ) and fluorine ( F ) co -doped TiO 2 powders were prepared by mixing TiCl 3 solutions with ammonium fluoride ( NH 4 F ). In preparation, we used NH 3- H 2 O solution for adjustment of pH values (pH 2, 7, and 9) of mixed solution. X-ray diffraction (XRD) indicated N , F - TiO 2 powders prepared at pH7 and pH9 contained only anatase phase, but the powders prepared at pH2 contained both anatase and rutile phase. The result of XRD also indicated N , F - TiO 2 powders prepared at pH7 had the smallest crystallite size. We measured photocatalytic activity of prepared N , F - TiO 2 powders by the decomposition of methylene blue. N , F - TiO 2 powder prepared at pH7 and pH9 showed same high photocatalytic activity under ultraviolet light irradiation (peak wave length = 352 nm). Furthermore, under green light LED irradiation (wave length = 525 nm), a sample prepared at pH7 decomposed methylene blue more quickly than any other samples. As the result, N , F - TiO 2 prepared at pH7 had the best catalytic activity under both UV-light and visible light in the all of N , F - TiO 2 prepared and reference TiO 2 photocatalyst (ST-01 produced by Ishihara Co. Ltd).

The Quantum Yield of Oxidation of Hevea Rubber and GR-S

1948 ◽  
Vol 21 (3) ◽  
pp. 639-653 ◽  
Author(s):  
E. J. Hart ◽  
M. S. Matheson
Keyword(s):  
Quantum Yield ◽  
Room Temperature ◽  
Wave Length ◽  
Radical Reaction ◽  
Quantum Yields ◽  
Initial Reaction ◽  
Free Radical Reaction ◽  
Stable Intermediate ◽  
A Chain ◽  
Reaction Chain

Abstract The initial quantum yields of photoöxidation for purified Hevea rubber have been measured for various mercury arc lines in the wave length region 2537– 17,400 A˚. All experiments were carried out at room temperature and at an oxygen pressure of one atmosphere. At the outset of irradiation all quantum yields of combined oxygen are less than unity, although the quantum efficiency rises above 1.0 at 2537 and 3130 A˚. as photoöxidation proceeds. The low quantum yield suggests that in its initial stages (less than 0.1 per cent oxygen combined on the rubber) photoöxidation is not a chain reaction. It is postulated as the first step in rubber photoöxidation that the light activated rubber group reacts with oxygen to give a relatively stable intermediate which does not immediately dissociate to give a free radical reaction chain. The quantum yields of photoöxidation of purified GR-S were also measured under the same conditions as used for rubber. At each wave length the quantum yield was lower than for rubber, indicating formation of a stable intermediate in the initial reaction also.

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