Absorption cross-sections organic nitrates

Roberts, J. M., and R. W. Fajer, UV Absorption Cross Sections of Organic Nitrates of Potential Atmospheric Importance and Estimation of Atmospheric Lifetimes, Enciron. Sci. Technol., 23, 945-951 (1989). 

One of the objectives of LACTOZ has been to provide absorption cross-sections and quantum yields so that photolysis rates can be calculated under atmospheric conditions. Emphasis has been on (a) refinement of data for the simple, well-characterised molecules (O3, HCHO) involved in HOx radical production, and (b) determination of data for photolysis of organic compounds formed as products in the degradation of alkanes, alkenes and selected multifunctional VOCs, mainly carbonyl compounds and nitrates, which produce HOx indirectly. 

Fig. 8 UV absorption cross-sections of several organic nitrates and dinitrates (Becker). Pyruvic Acid (CH3COCOOH)...

UV absorption spectra have been measured for the ketonitrates and dinitrates (LACTOZ 89). In the region of atmospheric interest (X > 270 nm) the absorption cross sections of the carbonyl nitrates are approximately a factor of 10 higher than those of the dinitrates. From the measured cross sections photolysis frequencies have been calculated for the organic ketonitrates and dinitrates. Although the photolysis frequencies represent upper limits the results indicate that photolysis will generally be somewhat more important than loss via reaction with OH radicals for saturated difunctional nitrates. However, for unsaturated nitrates loss due to reaction with OH will dominate over photolysis as an atmospheric sink. The product studies show that photolysis of ketonitrates/dinitrates will result in the re-release of NO2 and the formation of PAN-type compounds. 

Roberts, J.M., Fajer, R.W. UV absorption cross sections of organic nitrates of potential atmospheric importance and estimation of atmospheric lifetimes. Environ. Sci. Technol. 23, 945-951 (1989)... 

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