Ozone reactions with nitric oxide

Light emitted by oxidation reactions with ozone leads to the most numerous applications of chemiluminescence. A common example of CL in the gas phase is the reaction of nitric oxide with ozone ... 

Chemiluminescence. Chemiluminescence (262—265) is the emission of light duting an exothermic chemical reaction, generaUy as fluorescence. It often occurs ia oxidation processes, and enzyme-mediated bioluminescence has important analytical appHcations (241,262). Chemiluminescence analysis is highly specific and can reach ppb detection limits with relatively simple iastmmentation. Nitric oxide has been so analyzed from reaction with ozone (266—268), and ozone can be detected by the emission at 585 nm from reaction with ethylene. 

Chemiluminescent techniques have been used to determine nanomolar quantities of nitrate and nitrite in seawater [124,125]. This method depends on the selective reduction of these species to nitric oxide, which is then determined by its chemiluminescent reaction with ozone, using a commercial nitrogen oxides analyser. The necessary equipment is compact and sufficiently sturdy to allow shipboard use. A precision of 2nmol/l is claimed, and an analytical range of 2nmol/l with analysis rates of 10-12 samples hourly. 

In the chemiluminescent detection of nitrogen oxides, a constant source of ozone reacts with a metered air sample containing nitric oxide. Fontijn et al. suggested that this method could also be used for ozone detection by using a constant nitric oxide source for reaction with ozone in the air sample. The ozone-nitric oxide reaction is carried out at reduced pressure, to avoid quenching the chemiluminescent reaction. Detection of the emission in the spectral r on involved (600-3,000 nm) requires using a near-infrared-sensitive photomultiplier tube. The noise of such a photomultiplier tube is reduced by cooling it to about - 20 C. ... 

If some other reactant was introduced into the system to remove nitric oxide in competition with the ozone-nitric oxide reaction, it was predicted that the ozone would accumulate. Nitrogen pentoxide was found to produce the predicted effect photolysis of the nitrogen dioxide-nitrogen pentoxide-oxygen system yielded substantial quantities of ozone. 

Several commercial analyzers for the determination of gases are based on chemiluminescence. Nitric oxide (NO) can be determined by reaction with ozone (O3). The reaction converts the NO to excited NO2, with the subsequent emission of light. 

In the stratosphere nitric oxide is converted to nitrogen dioxide by reaction with ozone ... 

OH is converted to HO2 by reactions with carbon monoxide (Reaction (5.79)) and ozone (Reaction (5.90)), and HO2 is converted back to OH by reactions with nitric oxide (Reaction (5.92)) and ozone (Reaction (5.91)). The loss of HOx results from the conversion of OH and HO2 into soluble species like H2O2 and HNO3, followed by wet scavenging of these molecules through precipitation. 

Nitric oxide is quite rapidly oxidized to N02 by reaction with ozone. Nitrogen dioxide, in turn, is subject to photolysis whereby NO is regenerated. This leads to the following reaction sequence... 

The removal of NO2 from the atmosphere occurs via its oxidation and hydration to form nitric acid. In the course of the oxidizing process, NO3 may be formed by the reaction with ozone ... 

As so far described, photolysis of nitrogen dioxide can give rise to small steady-state concentrations of ozone, which are limited by the reaction with nitric oxide. Concentrations of ozone in city centers tend to be lower than those in adjacent rural areas due to fresh emissions of NO from traffic reacting with ozone, as above. Equating the rate of NO2 loss by photolysis to the rate of NO2 formation leads to the following expression for the concentration of ozone ... 

The reaction of ozone with nitric oxide (reaction [IV]) has been utilized for several analytical applications, including the determination of atmospheric nitric oxide, which has a linear response over six orders of magnitude and a detection limit of about one part in 10 by volume. The wavelength distribution of this chemiluminescence ranges from the visible to the near-infrared ... 

The nitric oxide is then determined by its reaction with ozone (reaction [I]). This reaction is specific and can be used for screening purposes without any kind of separation. Alternatively, it can be used as a detector for gas or liquid chromatography where the effluent passes through a pyrolysis chamber and the N-nitrosoamines decompose to form nitric oxide. The pyrolysis chamber consists of a quartz or ceramic tube with the catalyst coated onto the walls, or packed into the tube. The most effective catalyst has been found to be a mixture of tungsten oxides. 

The oxidation of sulfur monoxide with ozone (reaction [V]) is similar to that of nitric oxide (reaction [I]), but it is more exothermic. The chemiluminescence emission spectrum accompanying this reaction extends from about 260 to 480 nm. At least four excited states of sulfur dioxide are thought to be involved A2, and B2, which have radiative lifetimes of 8 ms, 30 ps, 600 ps, and 30 ns, respectively ... 

Other processes explored, but not commercialized, include the direct nitric acid oxidation of cyclohexane to adipic acid (140—143), carbonylation of 1,4-butanediol [110-63-4] (144), and oxidation of cyclohexane with ozone [10028-15-5] (145—148) or hydrogen peroxide [7722-84-1] (149—150). Production of adipic acid as a by-product of biological reactions has been explored in recent years (151—156). 

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