Absolute rate constant and O(<sup>3</sup>P) yield for the O(<sup>1</sup>D)+N<sub>2</sub>O reaction in the temperature range 227 K to 719 K

Abstract

Abstract. The absolute rate constant for the reaction that is the major source of stratospheric NO x , O( 1 D)+N 2 O → products, has been determined in the temperature range 227 K to 719 K, and, in the temperature range 248 K to 600 K, the fraction of the reaction that yields O( 3 P). Both the rate constants and product yields were determined using a recently-developed chemiluminescence technique for monitoring O( 1 D) that allows for higher precision determinations for both rate constants, and, particularly, O( 3 P) yields, than do other methods. We found the rate constant, k R1 , to be essentially independent of temperature between 400 K and 227 K, having a value of (1.37±0.11)×10 −10 cm 3 s −1 , and for temperatures greater than 450 K a marked decrease in rate constant was observed, with a rate constant of only (0.94±0.11)×10 −10 cm 3 s −1 at 719 K. The rate constants determined over the 227 K-400 K range show very low scatter and are significantly greater, by 20% at room temperature and 15% at 227 K, than the current recommended values. The fraction of O( 3 P) produced in this reaction was determined to be 0.002±0.002 at 250 K rising steadily to 0.010±0.004 at 600 K, thus the channel producing O( 3 P) can be entirely neglected in atmospheric kinetic modeling calculations. A further result of this study is an expression of the relative quantum yields as a function of temperature for the chemiluminescence reactions (k CL1 )C 2 H + O( 1 D) → CH(A) + CO and (k CL2 )C 2 H + O( 3 P) → CH(A) + CO, both followed by CH(A) → CH(X) + hν, as k CL1 (T )/k CL2 (T )=(32.8T −3050)/(6.29T +398).

Portable calibrator for NO based on the photolysis of N<sub>2</sub>O and a combined NO<sub>2</sub>∕NO∕O<sub>3</sub> source for field calibrations of air pollution monitors

“…An important fundamental difference is that the 184.9 nm absorption cross section for N 2 O is approximately 14 times larger than that of O 2 . The absorption cross section, σ , of N 2 O at the 184.9 nm mercury emission line is ∼ 1.4 × 10 −19 cm 2 molec −1 (Creasey et al, 2000;Cantrell et al, 1997) compared to ∼ 1 × 10 −20 cm 2 molec −1 for O 2 (Yoshino et al, 1992, Creasey et al, 2000. Also, O 2 is only 21 % of the air that passes through the photolysis chamber in the ozone calibrator, while N 2 O is supplied to the photolysis chamber by a source that is > 99 % N 2 O.…”

“…Nishida et al (2004) report a quantum yield for O( 3 P) from N 2 O photolysis of 0.005 ± 0.002 (i.e., NO 2 /NO = 0.005/1.22 ∼ 0.4 %). Quenching of O( 1 D) to O( 3 P) by N 2 O (Reaction R5c) likely contributes up to another 0.8 % (Vranckx et al, 2008, report a limit of φ 5c < 0.01 at 298 K). Oxygen (O 2 ), which is a typical N 2 O impurity, can also photolyze to produce two O( 3 P) atoms.…”

The impact of current CH4 and N2O atmospheric loss process uncertainties on calculated ozone abundances and trends

“…[], and Vranckx et al . []. The temperature dependence of the rate coefficient was derived from the results of Davidson et al, Dunlea and Ravishankara, and Vranckx et al using only data at <400 K after scaling to the recommended k (298 K) value.…”

“…The recommended 2σ uncertainty range in the total rate coefficient is included in Figure . The reactive channels (4a + 4b) of the O( 1 D) + N 2 O reaction have a combined yield greater than 99% [ Vranckx et al ., ].…”

Hydroxyl radicals in the tropical troposphere over the Suriname rainforest: airborne measurements

“…The quenching Reaction (R3e) is negligible compared to the other reactions (Vranckx et al, 2008). The flux can be calculated from the NO concentrations produced by irradiating defined mixtures of N 2 O in a carrier gas:…”