التفاصيل البيبلوغرافية
| العنوان: |
Shock Tube Measurements of the Rate Constant of the Reaction NCN + O2. |
| المؤلفون: |
Faßheber, Nancy, Friedrichs, Gernot |
| المصدر: |
International Journal of Chemical Kinetics; Sep2015, Vol. 47 Issue 9, p586-595, 10p |
| مصطلحات موضوعية: |
SHOCK tubes, CHEMICAL reactions, RADICALS (Chemistry), HIGH temperatures, BANDWIDTHS, SHOCK waves |
| مستخلص: |
The rate constant of the comparably slow bimolecular NCN radical reaction NCN + O2 has been measured for the first time under combustion relevant conditions using the shock tube method. The thermal decomposition of cyanogen azide (NCN3) served as a clean high-temperature source of NCN radicals. NCN concentration-time profiles have been detected by narrow-bandwidth laser absorption at v = 30383.11 cm-1. The experiments behind incident shock waves have been performed with up to 17% O2 in the reaction gas mixture. At such high O2 mole fractions, it was necessary to take O2 relaxation into account that caused a gradual decrease of the temperature during the experiment. Moreover, following fast decomposition of NCN3 and collision-induced intersystem crossing of the initially formed singlet NCN to its triplet ground state, an unexpected and slow additional formation of triplet NCN has been observed on a 100-µs timescale. This delayed NCN formation was attributed to a fast recombination of ¹NCN with O2 forming a 3NCNOO adduct acting as a reservoir species for NCN. Rate constant data for the reaction NCN + O2 have been measured at temperatures between 1674 and 2308 K. They are best represented by the Arrhenius expression k2/(cm³mol-1s-1) = 1.3 × 1012exp(-97kl mol-1/RT), (±57%). No pressure dependence has been observed at pressures between 216 and 706 mbar. [ABSTRACT FROM AUTHOR] |
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