Hydrocarbon early atmosphere

In the early 1950 s, it was reported by Haagen-Smit that many of the characteristics of photochemical smog could be explained by the presence of ozone and other photochemical oxidants. These substances, he believed, were formed in the atmosphere as a result of chemical reactions involving nitrogen oxides and hydrocarbons present in automobile exhaust. Significant quantities of nitrogen oxides were also emitted by power plants. 

Early attention focused on the most reactive of the hydrocarbons, the olefins, because it was expected and was observed by atmospheric sampling that they were preferentially consumed during smog formation. Lab-oratoiy studies confirm that olefln-NO mixtures are very prolific sources of ozone. However, these olefins are not essential to oxidant formation. 

The importance of OH radicals in atmospheric chemistry is the basis of another reactivity scale for organics that do not photolyze in actinic radiation (Darnall et al., 1976 Wu et al., 1976). This scale is based on the fact that, for most hydrocarbons, attack by OH is responsible for the majority of the hydrocarbon consumption, and this process leads to the free radicals (H02, R02) that oxidize NO to N02, which then leads to 03 formation. Even for alkenes, which react with 03 at significant rates, consumption by OH still predominates in the early portion of the irradiation before 03 has formed. It has therefore been suggested that the rate constant for reaction between OH and the... 

Mass Spectrometry. Mass spectrometric detection was used in early laboratory studies of H02 (103, 104) and has also been used in more recent investigations (105). The H02 peak at the mass-to-charge ratio mle = 33 is useful in laboratory identification and quantification, but in the atmosphere, most likely multiple species will interfere because of, for example, fragmentation of hydrocarbons, hydrogen peroxide, or oxygen isotopes. 

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