Atomic oxygen reactions

Usually atomic oxygen is produced by the same methods as those used for the production of atomic hydrogen, i.e. by electric discharge and photodissociation. 

The rate constants of more than 200 reactions of atomic oxygen with various molecules and radicals have hitherto been measured. The simplest reaction is 

The reactions of atomic oxygen with alkanes, aldehydes, alcohols, and alkyl halides have been reported to proceed mostly as follows 

According to [527] an excited singlet oxygen atom readily inserts into the C—H bond (in contrast to 0( P) the addition of which requires violation of the spin conservation rule). The same difference is observed for singlet and triplet methylene [36]. The insertion of methylene into C—H bonds can be considered to be reliably established. 

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Paulson, S. E., R. C. Flagan, and J. H. Seinfeld, Atmospheric Photooxidation of Isoprene. 1. The Hydroxyl Radical and Ground State Atomic Oxygen Reactions, hit. J. Chem. Kinet., 24, 79-101 (1992a). 

In case of atomic oxygen reactions the formation of formaldehyde was found to be characteristic for all compounds studied (naturally except NH3 and CO). As a rule, but not always, the main reaction is the formation of formaldehyde. For example, for dichloroethane the reaction proceeds with scission of the carbon bond, but CH2O does not appear to be the main reaction product. As the dichloroethane molecule contains chlorine, the main product will be HC1. The formation of a... 

The equation derived for the reaction rate constant is based on the scheme for atomic oxygen reactions with A molecules given on page 40. The quadratic and cubic processes are neglected, since it is always possible to carry out the reactions of 0 with substance A in such a way that primary, or secondary processes will prevail irrespective of the k value, but the A concentration should be high enough. An equation calculated without this assumption may be found in the paper of ref. 67. 

Regeneration of atomic chlorine, essential for catalysis, does not take place by means of reaction 8 because of the very low concentration of atomic oxygen (reaction 1 does not happen in the dark ). However, reaction 14 with bromine monoxide does occur instead. Furthermore, dimerization (equation 18) of chlorine monoxide18 is followed by photolysis (equation 19) and dissociation (equation 20) of the chloroperoxy radicals which serve to release chlorine atoms19. Thus arises the now famous Antarctic ozone hole, a very significant depletion in ozone concentrations at altitudes of 15-20 km during the austral... 

Gas-Phase Atomic Oxygen Reactions with Hydrocmbons... 

R. J. Cvetanovic, Kinetics and Mechanisms of Some Atomic-Oxygen Reactions, Proceedings of the NASA Workshop on Atomic-Oxygen Effects held in Pasadena, CA, 10-11 November 1986, NASA Contractor Report 181163, JPL Publication 87-14, Ed. D. E. Brinza (NASA, Paseidena, CA, 1987) pp. 47-54. 

M. Tagawa, M. Matsushita, M. Umeno and N. Ohinae, Laboratory Studies of Atomic-Oxygen Reactions on Spin-Coated Polyimide Films, Proceedings of the 6th International Symposium on Materials in a Space Environment, Noordwijk, The Netherlands, 19-23 September 1994, ESA SpeciaJ Pubhca-tion 368, Ed. T. D. Guyenne (European Space Agency, Paris, Prance, 1994) p. 189. 

Absolute atomic oxygen concentrations are best measured with the isothermal resistance probe. Elias et describe investigations of atomic oxygen reactions using a silver coated platinum wire coil. 

The catalytic destruction of ozone by NO is the most important process that occurs in the middle and upper stratosphere. We should stress here that this process is possible even in unpolluted atmosphere since small amounts of nitrous oxide, N2O, from biological denitrification have always been present in the stratosphere, which is the precursor of nitric oxide, NO, in reaction with atomic oxygen (reaction (11)). Most collisions with atomic oxygen form N2 and O2, but a few form NO (see also Section 4)... 

The most abundant reaction partner in the stratosphere is molecular oxygen [reaction (101)]. Maricq et al. [82] have measured a rate constant of (8.0 0.8) X 10 cm s for this reaction and found it to be temperature independent over the range 213 to 385 K. This suggests that the reaction is essentially barrierless, in agreement with ab initio calculations [167]. Another removal reaction is with atomic oxygen [reaction (102)]. This reaction has been studied experimentally by Ryan and Plumb [187], and computationally by Francisco and Ostafin [190]. The measured rate constant for the... 

When NOx concentration exceeds the threshold value of about 0.1%, the atomic oxygen reactions with nitrogen oxides, (6-74) and (6-75), become faster than their reactions with molecular oxygen (6-66) to form ozone. That actually explains the discharge poisoiung effect, which was first observed long ago by Andrews and Tait (1860). Even ozone molecules... 

Marsh H, O Hair TE, Wynne-Jones Lord, The carbon-atomic oxygen reaction - surface-oxide formation on para-crystalline carbon and graphite. Carbon 1969 7(5) 555-558. 

Tagawa, M. and Minton, T. K., Mechanistic studies of atomic oxygen reactions with polymers and combined effects with vacuum ultraviolet hght, MRS Bulletin, 35(1), 35-40 (2010). 

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