Mass-spectrometric determination of product branching probabilities for the NH2 + NO2 reaction at temperatures between 300 and 990 K

Product Branching Ratios of the NH2(X2B1) + NO2 Reaction

“…Table shows a comparison of our results with other recent work. The branching ratio for channel 1a obtained in the present work is in reasonable, although not in outstanding agreement with the study of Park and Lin. , The value reported here is significantly higher than in our previous study using 193 nm NH 3 photolysis, although the qualitative conclusion that channel 1a is a minor contribution at room temperature remains unchanged. Our results, however, differ dramatically from those obtained in the pulse radiolysis study by Meunier et al, who used the F + NH 3 reaction to form NH 2 radicals.…”

“…Although ammonia is a highly efficient NH 2 radical source, secondary sources of NO in that study (primarily due to reaction of photolytically produced hydrogen atoms with NO 2 ) prevented a quantitative determination of the yield of channel 1b. Park and Lin used mass spectrometry detection following NH 3 photolysis to obtain a branching ratio of φ 1a = 0.19 ± 0.02, which was found to be independent of temperature over the range 300−900 K. , Electron impact cracking of NO 2 produces a large amount of NO in their experiment, again preventing determination of φ 1b . Meunier et al, however, used a pulse radiolysis source and infrared detection, estimating φ 1a = 0.59 ± 0.03 and φ 1b =0.40 ± 0.05 at 298 K .…”

Absence of isotope exchange in the reaction of N2O + O(1D) and the global Δ17O budget of nitrous oxide

“…More recent model calculations by Kohlmann and Poppe [1999] adopted a re-measured value of 60% for the branching ratio [Meunier et al, 1996], which -together with a number of other revisions -gave an estimated N 2 O source of only 0.2 Tg N a À1 . Other studies report even lower branching ratios [Lindholm and Hershberger, 1997;Park and Lin, 1996] [Michalski et al, 2003], the contribution of the NH 2 + NO 2 source is likely to be at the higher end of the estimate here, because D 17 O(NO 2 ) is expected to be between 0.9 and 1.5 times D 17 O(HNO 3 ), depending on the formation pathway (hydrocarbon oxidation by NO 3 , heterogeneous hydrolysis of N 2 O 5 or gas-phase reaction of NO 2 + OH).…”

An experimental, theoretical and kinetic-modeling study of the gas-phase oxidation of ammonia

“…12,13 Studies on oxidation focused first on NH 3 flame chemistry [14][15][16] and on its use within the Thermal DeNO x process 17 for the selective non-catalytic reduction of nitrogen oxides (NO x ). Later, oxidation chemistry was studied at a fundamental level through targeted experiments [18][19][20] and theoretical methodologies. [21][22][23][24] As a result, NH 3 kinetic mechanisms have largely benefited from incremental improvements.…”