The effect of collision energy on the stereodynamics of the reaction triatomic NH₂ system

Abstract

The stereodynamics of the reaction H(²S) + NH (v = 0, 1, 2, 3; j = 0) → N(⁴S) + H₂ are studied using the quasi-classical trajectory method on a double many-body expansion potential energy surface to understand the alignment and orientation of the product molecules in the collision energy range of 2–20 kcal·mol⁻¹. The vibrational–rotational quantum number of the NH molecules is specifically investigated for v = 0, 1, 2, and 3 and j = 0. The $P\left({\theta }_r\right),$ $P\left({\varphi }_r\right),$ $P\left({\theta }_r,{\varphi }_r\right),$ differential cross section [DCS; $(2\pi /\sigma )(d{\sigma }_{00}/d{\omega }_t)$], and average rotational alignment factor $〈P_2\left(\text{cos}\hspace{0.17em}{\theta }_r\right)〉$ are calculated. The stereodynamics results indicate that the reagent vibrational quantum number and initial collision energy significantly affect the distributions of the k–j′, k–k′–j′ and k–k′ vector correlations along with $〈P_2\left(\text{cos}\hspace{0.17em}{\theta }_r\right)〉.$ In addition, while DCS is extremely sensitive to the collision energy, it is not significantly affected by the vibrational excitation of the reagents.

Keywords:

• Quasi-classical trajectory method
• stereodynamics
• potential energy surface
• vector correlation

Additional information

Funding

This work was supported by the National Natural Science Foundation of China (Grant No. 11704172) and the National Undergraduate Scientific and Technological Innovation Project (201610451011, 201710451477).