Ozone, photodissociation

Madronich, S., and C. Granier, Impact of Recent Total Ozone Changes on Tropospheric Ozone Photodissociation, Hydroxyl Radicals, and Methane Trends, Geophys. Res. Lett., 19, 465-467 (1992). 

The peak of the O2 photodissociation occurs in the stratosphere (near 35 km for an overhead sun) where the total number of 02 molecules pho-todissociated is of the order of 107 cm-3 sec-1. Below the ozone peak (<25 km) the photodissociation rate decreases rapidly, particularly when the solar zenith angle increases. Below 20 km, the atomic oxygen production becomes very small and there is no atomic oxygen production in the troposphere by the 02 photodissociation. The ozone photodissociation is the result of the absorption of solar radiation in the visible and the ultraviolet ... 

However, in the stratosphere, where H20 is not photodissociated, it is necessary to consider a reaction involving the ozone photodissociation. This is a process in which an excited oxygen atom O( D) reacts with a molecule to produce H and OH (Fig. 4) as follows ... 

Sheppard, M.G. and Walker, R.B. (1983). Wigner method studies of ozone photodissociation, J. Chem. Phys. 78, 7191-7199. 

The main atmospheric cleaner is ozone, photodissociation of which ... 

Several authors have been able to show experimentally that natural air containing trace amounts of SO2, exposed to sunlight, is photochemical-ly oxidized and that the rate of SO2 oxidation was a complex function of the trace gas composition of the air mixture (NO, NO2 - hydrocarbons level and composition). The oxidation of SO2 within the natural troposphere is therefore expected to occur largely through reactions 7,8 and 9 of table I. The main mechanism is through radicals which might be formed in various ways such as from ozone photodissociation and from the reaction ... 

Madronich S. and Granier C. (1992) Impact of recent total ozone changes on tropospheric ozone photodissociation, hydroxyl radicals, and methane trends. Geophys. Res. Lett. 19, 465 67. 

Figure 4.37 shows the relative contribution of each band to the ozone photolysis frequency as a function of altitude. It should be noted that the value of the ozone photodissociation coefficient depends critically on the absorption by ozone itself, introducing a nonlinear coupling as a function of altitude. The calculation of Jo3 must include the effects of molecular scattering and albedo (see Figure 4.38). 

Ozone photodissociates to produce either ground-state atomic oxygen... 

Ndengue SA, Schinke R, Gatti F, Meyer H-D, lost R (2012) Ozone photodissociation isotopic and electronic branching ratios for asymmetric isotopologues. J Phys Chem A 116 12271... 

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