Abstract
The major atmospheric reactions of N-nitrosodimethylamine (NDMA) and dimethylnitramine (DMN) have been investigated in an approx.3500-L environmental chamber utilizing in situ long-path Fourier transform infrared spectroscopy. Rate constants for the reactions of OH radicals with NDMA and DMN were measured relative to that for dimethyl ether at 298 +/- 2K and resulted in values of k(OH + NDMA) = (3.0 +/- 0.4) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/ and k(OH + DMN) = (4.5 +/- 0.5) x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/. Rate constants for the reactions of O/sub 3/ with NDMA and DMN were determined to be less than or equal to 1 x 10/sup -20/ and less than or equal to 3 x 10/sup -21/ cm/sup 3/ molecule/sup -1/ s/sup -1/, respectivley. The photolysis rate NDMA measured in the presence of excess O/sub 3/ indicated the photodissociation quantum yield to be unity for lambda >/approx.290 nm. The photolysis of NDMA in O/sub 3/ resulted in the formation of approx.65% DMN together with lesser yields of HCHO, CH/sub 3/NO/sub 2/, and CO. A mechanism accounting for the observed products is presented. The rapid photolysis of NDMA leads to a tropospheric half-life of onlymore » approx.5 min, while a half-life of approx.2 days is predicted for DMN, with its major removal process being reaction with OH radicals.« less
Published Version
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