Carbon monoxide photodissociation from

The darkness associated with dense interstellar clouds is caused by dust particles of size =0.1 microns, which are a common ingredient in interstellar and circum-stellar space, taking up perhaps 1% of the mass of interstellar clouds with a fractional number density of 10-12. These particles both scatter and absorb external visible and ultraviolet radiation from stars, protecting molecules in dense clouds from direct photodissociation via external starlight. They are rather less protective in the infrared, and are quite transparent in the microwave.6 The chemical nature of the dust particles is not easy to ascertain compared with the chemical nature of the interstellar gas broad spectral features in the infrared have been interpreted in terms of core-mantle particles, with the cores consisting of two populations, one of silicates and one of carbonaceous, possibly graphitic material. The mantles, which appear to be restricted to dense clouds, are probably a mixture of ices such as water, carbon monoxide, and methanol.7... 

J. A. Westrick, J. L. Goodman, K. S. Peters. A Time-Resolved Photoacoustic Calorimetry Study of the Dynamics of Enthalpy and Volume Changes Produced in the Photodissociation of Carbon Monoxide from Sperm Whale Carboxymyoglobin. Biochemistry 1987, 26, 8313-8318. 

Teng, T. Y., Srajer, V., and Moffat, K. 1997. Initial trajectory of carbon monoxide after photodissociation from myoglobin at cryogenic temperatures. Biochemistry 36 12087-12100. 

Decomposition of carbon monoxide takes place when it is exposed to radiation of wavelength 1,295 A, but not when exposed to 1,470 A -0. Herzberg2i5 has concluded from this that Z)(CO)<9-57 eV, but Gaydont< 6 has pointed out that when vibrational and rotational energy are taken into account the upper limit may be as high as 10 1 eV, and further that it is not established that photodissociation is the primary act in the reaction. 

Photolysis of dimethylketene, which underwent thermal dimerization into tetramethyl-cyclobutane-1,3-dione, gave tetramethylcyclopropanone 1, together with 2,3-dimethylbut-2-ene (from dimethylcarbene dimerization) and carbon monoxide (from ketene photodissociation). Formation of the three-membered ring most probably arises from the addition of dimethylcarbene to dimethylketene. ... 

The second of these is more important than the first one, since the OH radicals are converted to H02 mainly by reacting with methane and carbon monoxide rather than with ozone. All these losses are at least partially retrieved, however, by the formation of ozone from the photodissociation of N02 when NO is converted to N02 in smog-like reactions involving the oxidation of methane and carbon monoxide, as was first pointed out by Crutzen (1973). In fact, more ozone may be formed in this manner than is lost by the conversion of O( D) to OH radicals, if conditions are favorable. The oxidation of methane and carbon monoxide was discussed in Section 4.2. Here, we will reconsider it from the viewpoint of its ozone generating potential. 

Carbon monoxide metastable TOF spectra for ketene photodissociation at 351 nm were taken from jco = 3-18. There was no difference in the shapes of the TOF spectra when the polarization of the probe laser was changed with respect to the flight path. Thus, our results are not sensitive to whatever vector correlations may exist in this photodissociation and the line strength factor of Eq. 38 can be ignored. The resulting F( lrans) functions reveal that... 

Aldehydes show an elimination reaction (loss of carbon monoxide, CO), that is not possible with ketones. Butanal, for example, photodissociates to propane and carbon monoxide. Cyclic ketones dissociate to a diradical (41 from cyclopentanone), which then reacts in any of several ways including elimination to ethene or 42 and coupling to cyclobutane. Formation of cyclobutane and ethene is accompanied by expulsion of CO prior... 

Maricq et al. [180] have studied the self-reaction of FCO radicals. Although the self-reaction will be of minor importance for upper atmospheric chemistry, this reaction is critical in laboratory studies involving FCO radicals. For example, in the measurement of quantum yields from CFjO, CFCIO, and HFCO photodissociation, the self reaction could lead to a gross underestimation of the quantum yields. The rate coefficient of 1.9 0.2 X 10 cm s suggests that the self-reaction is quite rapid. In the self-reaction, the FCO radicals recombine to form oxylfluoride, which is produced with excess energy above the barrier for molecular dissociation to carbonyl fluoride and carbon monoxide [192]. 

Straub, J. E. Karplus, M., Molecular dynamics study of the photodissociation of carbon monoxide from myoglobin Ligand dynamics in the first lOps. Chem. Phys. 1991, 158, 221-248. 

All of these seemingly different reactions of Fe(CO)5 result from the initial photodissociation of a carbonyl ligand. The thermally stable precursor compound Fe(CO)5 is a pentacoordinate coordinately saturated complex that dissociates a carbon monoxide molecule upon irradiation with light ... 

Sulfuric acid is produced in the upper atmosphere of Venus by the Sun s photochemical action on carbon dioxide, sulfur dioxide, and water vapor. Ultraviolet photons of wavelengths less than 169 nm can photodissociate carbon dioxide into carbon monoxide and atomic oxygen. Atomic oxygen is highly reactive. When it reacts with sulfur dioxide, a trace component of the Venusian atmosphere, the result is sulfur trioxide, which can combine with water vapor, another trace component of Venus s atmosphere, to yield sulfuric acid. In the upper, cooler portions of Venus s atmosphere, sulfuric acid exists as a liquid, and thick sulfuric acid clouds completely obscure the planet s surface when viewed from above. The main cloud layer extends from 45-70 km above the planet s surface, with thinner hazes extending as low as 30 km and as high as 90 km above the surface. The permanent Venusian clouds produce a concentrated acid rain, as the clouds in the atmosphere of Earth produce water rain. 

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