Quantum calculations of nonadiabatic 2A1–2B2 conical-intersection effects in the reactions and N(4S)+O2(A3Δu)

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

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.

Dynamics of Inelastic and Reactive Collisions of 16O(3P) with 15N18O

The dynamics of O(³P) + NO collisions were investigated at a collision energy of ⟨E_coll⟩ = 84.0 kcal mol^-1 with the use of a crossed molecular beams apparatus employing a rotatable mass spectrometer detector. This experiment was performed with beams of ¹⁶O atoms and isotopically labeled ¹⁵N¹⁸O molecules to enable the products of reactive and inelastic scattering to be distinguished. Three scattering pathways were observed: inelastic scattering (¹⁶O + ¹⁵N¹⁸O), O-atom exchange (¹⁸O + ¹⁵N¹⁶O), and O-atom abstraction (¹⁸O¹⁶O + ¹⁵N). All product channels exhibited a preponderance of forward scattering, but scattering over a broad angular range was also observed for all products. For inelastic scattering, an average of 90% of the collision energy is retained in the translation of ¹⁶O and ¹⁵N¹⁸O. On the other hand, for O-atom exchange (which also leads to O + NO products), the collision energy is partitioned roughly evenly between the translation of ¹⁸O + ¹⁵N¹⁶O and the internal excitation of ¹⁵N¹⁶O. The available energy for O-atom abstraction is significantly lower than the collision energy because of the endoergicity of this reaction, but the available energy is again roughly evenly partitioned between the translation of ¹⁸O¹⁶O + ¹⁵N and the internal excitation of the molecular (O₂) product. The relative yields of the three scattering pathways were determined to be 0.751 for inelastic scattering, 0.220 for O-atom exchange, and 0.029 for O-atom abstraction.