Reactive, Inelastic, and Dissociation Processes in Collisions of Atomic Nitrogen with Molecular Oxygen

Abstract

Collisions of atomic nitrogen with molecular oxygen have been treated with the quasiclassical trajectory method (QCT) in order to obtain a complete database of vibrationally detailed cross sections and rate coefficients for reactive, inelastic, and dissociation processes. For reaction rate coefficients, the agreement with experimental and theoretical data in the literature is excellent on the whole available interval 300–5000 K, with reliable extension to 20,000 K. For the inelastic case and for dissociation, no comparisons are available; therefore, a study of QCT reliability is proposed. In the inelastic case, it is found that “purely inelastic” and “quasireactive” collisions show not only different mechanisms but also different QCT levels of reliability at low energy. For dissociation, similar considerations bring to the conclusion that for the present collisional system, the QCT method is appropriate on the whole energy range studied. Rate coefficients for all the processes studied are provided in the electronic form.

Reaction of the N Atom with Electronically Excited O2 Revisited: A Theoretical Study

“…Presently, there is an acceptable consensus among the experimental data available in the literature on the R1 reaction thermal rate constant. ,− Specifically, the rate constant approximation proposed by Fernandez et al, elaborated initially for the temperature interval T = 400–1220 K [ k ( T ) = 1.20 × 10 6 T 2.15 exp­(−2557/ T ) cm 3 mol –1 s –1 ], in fact, , is in good consistency with the other measurements in a much wider temperature range. ,,− However, there are still problems with the quantitative interpretation of these data. Particularly, some theoretical studies ,− ,, using the precise potential energy surfaces (PESs) and advanced methods for calculating the thermal rate constants, such as the quasi-classical trajectory (QCT) approach and even wave packet (WP) dynamics, markedly (by more than an order of magnitude) underestimated the low-temperature measurements. − , Only just recently, Esposito and Armenise have succeeded in QCT simulations in obtaining the R1 thermal rate constant, which is consistent with experimental data over a wide temperature range.…”

“…The reaction of the ground-state atomic nitrogen ( 4 S) with normal oxygen molecules is one of two principal elementary channels involved in the Zeldovich mechanism for high-temperature conversion of air N 2 to nitrogen oxides (NO x ), − while this mechanism, also known as the “thermal NO” one, underlies the complex chemical kinetic models describing the NO x pollutant emission from combustion or high-temperature industrial processes − and the nitrogen oxidation in re-entry flows. − The kinetics of the R1 process has been extensively studied for a long time, both experimentally (see for the low-, − elevated-, , and high-temperature measurements , ) and theoretically. ,− In addition, there are some available experimental − and theoretical data ,,− ,,,,,, on the nascent distribution of vibrationally excited NO­( v ) formed in the R1 reaction.…”

Dynamics on Multiple Potential Energy Surfaces: Quantitative Studies of Elementary Processes Relevant to Hypersonics

“…135 perimental data [136][137][138] are extracted from the vibrational relaxation time parameters (pτ vib ) following the Bethe-Teller model. 139 In a recent study, 134 QCT calculated VR rates are found to significantly underestimate the experimental results. The VR rates calculated from QCT simulations in this work using the HB and GB schemes are shown in Figure 5.…”

“…The reverse reaction and the N 2 dissociation are also studied recently and rate expressions are reported. 133,134 In another recent study the PESs for the two lowest triplet states of N 2 O have been reconsidered based on MRCI+Q/aug-cc-pVTZ calculations. 135 The grid was considerably extended, in particular for the diatomic separation (r), and in the long range interaction region (along R) was treated more accurately.…”

“…Olive dashed line is a double Arrhenius type fit to the experimental result 140. Rates obtained in this work from QCT simulations and using HB and GB schemes are given along with the full QCT (magenta solid line) and quasi-reactive QCT (blue solid line) results from Ref 134. Data taken from Ref 135.…”