An Upper Limit on the Formation of NO(X²Π_r) in the Reactions + O(³P) and + at 298 K

Abstract

The concentration of the product nitric oxide, [NO(X 2 Π r )] product , formed in the title reactions is measured as a function of the vibrational energy distribution in the N 2 (A 3 Σ u + ) for V′ e 6 in a rapidly pumped dischargeflow reactor at ∼298 K and a total pressure of ∼2 Torr using laser-excited fluorescence techniques. For the reaction N 2 (A 3 Σ u + ,V′ e 2) + O( 3 P) there is no [NO(X 2 Π r )] observed detected above the noise in the background emission signal. Correcting this null measurement for competing reactions, the NO(X 2 Π r ) + N( 4 S, 2 D) product yield accounts for e2% (signal-to-background noise ) 1, 1σ) of the [N 2 (A 3 Σ u + ,V′)] total . For the reaction N 2 (A 3 Σ u + ,V′ e 6) + O( 3 P) the [NO(X 2 Π r )] observed is seen to increase slightly relative to the reaction N 2 (A-3 Σ u + ,V′ e 2) + O( 3 P). Correcting the [NO(X 2 Π r )] observed for competing reactions, the NO(X 2 Π r ) + N( 4 S, 2 D) product yield accounts for 5.7 ( 1.1% of the [N 2 (A 3 Σ u + )] total and as much as 57 ( 14% of the [N 2 -(A 3 Σ u + ,3 e V′ e 6)]. For the reaction N 2 (A 3 Σ u + ,V′ e 6) + O 2 (X 3 Σ g -) no [NO(X 2 Π r )] observed is detected above the noise in the background emission signal. Correcting this null measurement for competing reactions, the NO(X 2 Π r ) + NO(X 2 Π r ) product yield represents <0.1% of the [N 2 (A 3 Σ u + ,V′)] total . Possible implications of these observations are discussed.

Study of fast gas heating in a capillary nanosecond discharge in air. TALIF O atoms measurements and kinetic modeling.

“…The Ratio of reaction channels for N 2 (A 3  ,v) quenching by oxygen atoms has been studied in Ref. 5:…”

Active nitrogen and oxygen: Enhanced emissions and chemical reactions

“…(ii) The vibrational level specific bimolecular chemical reaction rate constants for N 2 ðA 3 R þ u ; mÞ quenching by O( 3 P) used [74] for the determination of the above fraction of the N 2 ðA 3 R þ u ; mÞ chemical reactions are expected to have also been affected, as shown earlier (Section 5.1) in this work.…”

“…It should also be noted that, in contrast to the assumed [14,30,57,58] {O 2 (a 1 D g ) + N( 4 S)} chemical reaction, there is clear evidence of O( 1 S) product formation assigned to the fN 2 ðA 3 R þ u Þ þ Oð 3 PÞg chemical reaction [54,55,73,74]. However, the reported branching fraction {>0.25 [55], (0.75 ± 0.13) [54] and (0.80 ± 0.25) [73]} for O( 1 S) product formation was estimated from the variation of the concentration ratio ½Oð 1 SÞ=½N 2 ðA 3 R þ u ; m ¼ 0Þ as a function of the O( 3 P) atom concentration.…”

“…Similarly, the reported branching fraction for NO(X 2 P r ) product formation [74] in the study of the chemical reactions fN 2 ðA 3 R þ u ; mÞ þ Oð 3 PÞg, is also expected to have been affected by the above-mentioned (Section 5.1) extraneous change in ½N 2 ðA 3 R þ u Þ caused by the energy transfer reac-…”

“…u Þg chemical reaction has not been taken into consideration along with the other N 2 ðA 3 R þ u Þ removal processes [74] in the determination of the reported fraction of the chemical reactions of N 2 ðA 3 R þ u ; mÞ that proceed via the fN 2 ðA 3 R þ u ; mÞ þ Oð 3 PÞg chemical reaction path under pseudounimolecular conditions. (ii) The vibrational level specific bimolecular chemical reaction rate constants for N 2 ðA 3 R þ u ; mÞ quenching by O( 3 P) used [74] for the determination of the above fraction of the N 2 ðA 3 R þ u ; mÞ chemical reactions are expected to have also been affected, as shown earlier (Section 5.1) in this work.…”