Ozone chemiluminescence reactions

Various approaches have been described to convert other nitrogen species to NO before detection by the ozone chemiluminescence reaction. The most common converter is hot molybdenum, which converts all of the higher... 

Kummer et al. 8) have reported that at pressures of about 0.5 torr, the relative emission intensities of the higher olefins and of the organic sulfides were substantially greater than that of ethylene Table II summarizes the reported relative emission intensities. Since a recently developed commercial ozone monitor is based on the chemiluminescent reaction between ozone and ethylene, this suggests the possibility of using the sulfide-ozone chemiluminescent reaction to monitor the low concentration of sulfur compounds in ambient air. This possibility is being further investigated now. 

O ne. Air pollution (qv) levels are commonly estimated by determining ozone through its chemiluminescent reaction with ethylene. A relatively simple photoelectric device is used for rapid routine measurements. The device is caHbrated with ozone from an ozone generator, which in turn is caHbrated by the reaction of ozone with potassium iodide (308). Detection limits are 6—9 ppb with commercially available instmmentation (309). 

Nickel Carbonyl The extremely toxic gas nickel carbonyl can be detected at 0.01 ppb by measuring its chemiluminescent reaction with ozone in the presence of carbon monoxide. The reaction produces excited nickel(II) oxide by a chain process which generates many photons from each pollutant molecule to permit high sensitivity (315). 

The chemiluminescence reaction between nitrogen monoxide and ozone is formulated as ... 

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. 

Typically, intense chemiluminescence in the UV/Vis spectral region requires highly exothermic reactions such as atomic or radical recombinations (e.g., S + S + M - S2 + M) or reactions of reduced species such as hydrogen atoms, olefins, and certain sulfur and phosphorus compounds with strong oxidants such as ozone, fluorine, and chlorine dioxide. Here we review the chemistry and applications of some of the most intense chemiluminescent reactions having either demonstrated or anticipated analytical utility. 

The chemiluminescent reaction of SO with ozone is the basis of the sulfur chemiluminescence detector (SCD) [23] discussed later in this chapter,... 

Chemiluminescence is believed to arise from the 2Bj and the 2B2 electronic states, as discussed above for the reaction of NO with ozone [17]. The primary emission is in a continuum in the range =400-1400 nm, with a maximum at =615 nm at 1 torr. This emission is significantly blue-shifted with respect to chemiluminescence in the NO + 03 reaction (Xmax = 1200 nm), as shown in Figure 2, owing to the greater exothermicity available to excite the N02 product [52], At pressures above approximately 1 torr of 02, the chemiluminescence reaction becomes independent of pressure with a second-order rate coefficient of 6.4 X 10 17 cm3 molec-1 s-1. At lower pressures, however, this rate constant decreases and then levels off at a minimum of 4.2 X 1(T18 cm3 molec-1 s-1 near 1 mtorr, and the emission maximum blue shifts to =560 nm [52], These results are consistent with the above mechanism in which the fractional contribution of (N02 ) to the emission spectrum increases as the pressure is decreased, therefore decreasing the rate at which (N02 ) is deactivated to form N02. Additionally, the radiative lifetime and emission spectrum of excited-state N02 vary with pressure, as discussed above for the NO + 03 reaction [19-22],... 

Finlayson, B. J., J. N. Pitts, Jr., and R. Atkinson. Low-pressure gas-phase ozone-olefin reactions. Chemiluminescence, kinetics, and mechanisms. J. Amer. Chem. Soc. % 5356-5357, 1974. 

In 1965, a gas-phase chemiluminescent reaction between ozone and ethylene was reported by Nederbragt et and the sensitivity of this technique was later improved by Warren and Babcock.The reaction between ozone and ethylene yields chemiluminescent emission in the 300- to 600-nm region, with maximal intensity at 435 nm. The intensity of this emission is directly proportional to the ozone concentration. 

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. ... 

However, of all the methods used to measure ozone, the chemiluminescence reaction with ethylene is the one most often used. 

Figure 12.12—Chemiluminescence reactions using ozone. Schematic showing the principle of a nitrogen analyser based on the luminescence of nitrogen monoxide.

This technique calls for drying the sample in a liq drying column using Linde 4A molecular sieves (water detn), and then using the near IR spectrum between 2.2 and 1.7 micrometers to determine the ratio of UDMH to diethylenetriamine] 5) H.N. Voltrauer, Hydrazine Analysis Using Chemiluminescence , SAM-76-37, Aero Chem Res Lab, Princeton, Contract F41609-76-C-0029 (1976) [A procedure is reported using the chemiluminescent reactions of ozone with monomethylhydrazine and Aero-zine-50 (UDMH/hydrazine in 50/50 wt %) to... 

Thus, for a nitric oxide sensor dependent on ozone chemiluminescence, a 1.5-liter reaction chamber operating at 60 torr with a flow of 1.0 standard liter per second has a residence time of approximately t = (1.5/1.0) X (60/ 760) = 0.12 s. 

The reaction between olefins and ozone produces light that can be measured and related to the concentration of the reactants. One of the preferred methods for measuring ambient ozone concentrations utilizes the chemiluminescence generated in the ozone-ethylene reaction for detection. Recently, Hills and Zimmerman (16) described the use of this detection principle for determining hydrocarbon concentrations. They utilized the chemiluminescence created when ozone reacts with isoprene for development of a continuous, fast-response isoprene analyzer. This real-time isoprene system is reported to be linear over three orders of magnitude and to have a detection limit of about 1 ppbv. Because the system doesn t include a preseparation of hydrocarbons, interferences from other olefins (ethylene, propylene, and so forth) could occur. Thus far the chemiluminescent detector has been used to monitor isoprene emissions under conditions in which the concentrations of olefins that could interfere are negligible compared to those of the biogenic hydrocarbon. 

An alternative to FPD in the sulfur mode is the sulfur chemiluminescence detector (SCD) (48). This detector works by forming sulfur monoxide in a reducing flame. Sulfur monoxide is detected by its chemiluminescent reaction with ozone. The SCD is at least one order of magnitude more sensitive than most FPDs. It provides a linear response with high selectivity and does not suffer considerably from quenching. 

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