Product state distribution and stereodynamics of the O(1D) + N2O reaction

Abstract

The vibrational state distribution and the stereodynamics of product NO in the highly exothermic O( 1 D) + N 2 O reaction are compared with those of OH produced in the O( 1 D) + H 2 O reaction which proceeds via a long-lived HOOH collision complex. In opposition to the expectation from the lifetime of the collision complex, the product NO showed rather statistical vibrational distribution and isotropic differential cross section (DCS). Further, the product OH of the O( 1 D) + H 2 O reaction was found to preferentially rotate within the plane spanned by the reactant and product velocity vectors, whereas the direction of the product rotational axis is quite isotropic in the O( 1 D) + N 2 O reaction. Such features negate the simple-minded expectation from the lifetime of the collision complex. The real factor determining the product energy distribution is the mass combination in the collision complex. The heavy mass combination in the O( 1 D) + N 2 O reaction causes the efficient momentum coupling among the local modes of the collision complex which in turn facilitates the vibrational energy randomization to produce the statistical distribution in the vibrational state and the isotropic distribution in the product rotational axis.