Reactive and Nonreactive Collisions between NO(X²Π) and O(³P) under Hyperthermal Conditions

Abstract

Quasiclassical trajectory calculations are performed for hyperthermal collisions between NO­(X2Π) and O­(3P) on recently developed potential energy surfaces for the lowest doublet and quartet states of the NO2 system. Three product channels are investigated, and their branching fractions are in reasonably good agreement with the recent crossed molecular beam study at 84 kcal/mol of collision energy. The dominant inelastic channel has a strong forward scattering bias and a high translational energy distribution with limited internal excitation in the scattered NO. The exchange channel has significantly higher NO internal excitation and is also forward biased. The abstraction channel producing internally excited O2 has the smallest branching fraction and a broader angular distribution also with a forward peak. The angular and translational energy distributions in the three channels are consistent with experiment, but the agreement is not always quantitative. The sources of the differences are discussed. Finally, the impact of NO vibrational excitation on the reactive channels and the corresponding rate coefficients are reported.

Experimental and Theoretical Studies of Hyperthermal N + O2 Collisions

“…Although these extensive previous studies provided a detailed characterization of the N + O 2 system, both existing theoretical and experimental investigations lack information about nonreactive and reactive collisions of N + O 2 under the extreme conditions in hypersonic shock layers, where collision energies may be tens of kcal mol –1 . Caracciolo et al have recently reported an experimental study on the reverse of Reaction at a collision energy of ⟨ E coll ⟩ = 84.0 kcal mol –1 , and subsequent theoretical calculations by Lu et al have reasonably reproduced most of the measurements . In addition, theoretical studies of the NO + O reaction have been reported by Castro-Palacio et al , In the present paper, a joint experimental and theoretical investigation involving all three of these groups on the dynamics of hyperthermal N + O 2 collisions is reported.…”

“…Caracciolo et al have recently reported an experimental study on the reverse of Reaction 1 at a collision energy of ⟨E coll ⟩ = 84.0 kcal mol −1 , 38 and subsequent theoretical calculations by Lu et al have reasonably reproduced most of the measurements. 39 In addition, theoretical studies of the NO + O reaction have been reported by Castro-Palacio et al 24,32 In the present paper, a joint experimental and theoretical investigation involving all three of these groups on the dynamics of hyperthermal N + O 2 collisions is reported. We focus our attention on products generated from nonreactive (1a) and reactive (1b) collisions:…”

Quantum and semiclassical studies of nonadiabatic electronic transitions between N(4S) and N(2D) by collisions with N2

“…Such exchange channels are known to be efficient in hyperthermal collisions. [49][50][51][52] In our calculations reported here, (R2) is either implicitly included in the WP calculations, through the use of a damping term, or explicitly included in the CSDM calculations. As shown in this work, the adiabatic exchange channel (R2b) has much larger rate coefficients than the nonadiabatic channels (R-1 and (R2a)).…”

Low-temperature kinetics for the N + NO reaction: experiment guides the way

“…In light of the present results, these reactions involving atomic nitrogen should be reviewed in future astrochemical modeling studies to determine whether their rate coefficients need to be reevaluated, supported and accompanied by simulations such as those carried out here and for other, related systems. 9,49,[61][62][63][64] In summary, this joint experimental and theoretical investigation of the N + NO reaction allowed us to determine rate coefficients for this process at room temperature and below (30-300 K). Experiments were conducted down to 50 K on a supersonic flow (Laval nozzle) type apparatus employing pulsed laser photolysis for the (indirect) production of ground state atomic nitrogen and pulsed laser induced fluorescence at VUV wavelengths to detect these atoms.…”

“…In light of the present results, these reactions involving atomic nitrogen should be reviewed in future astrochemical modeling studies to determine whether their rate coefficients need to be reevaluated, supported and accompanied by simulations such as those carried out here and for other, related systems. 9,49,61–64…”