The stereodynamics of the inelastic collisions of NO(A2Σ+) with atoms and molecules

Abstract

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A newly constructed crossed molecular beam velocity map imaging experiment is used to study vector correlations for the rotationally inelastic collisions of NO(A2Σ+) with a range of atoms and diatomic molecules. Measurements are made of the differential cross section (DCS), and the  2 qA (θ) moments. Where possible, the experimental vector correlations are compared to the results of quantum scattering (QS) calculations performed on literature ab initio potential energy surfaces (PESs). Collisions of NO(A) with Ar and Ne lead to distinct features in the DCS, with a sharp, forward-scattered peak caused by scattering through the attractive region of the PES, and broader, higher-angle rotational rainbow peaks caused by scattering through the repulsive region of the PES. Sharp, angle-dependent fluctuations are observed in the   2  qA (θ) moments. While there is generally good agreement between the experimental and QS results, deviations in the QS DCS highlight inaccuracies in the literature PESs. Collisions of NO(A) with He are controlled entirely through interactions on the repulsive region of the PES. Excellent agreement between experiment and QS calculations was found for both the DCS and 2 q A (θ) moments, showing that the literature PES is accurate. Collisions of NO(A) with D2 produced results similar to He, showing that the uncalculated NO(A)-D2 PES is similar to the NO(A)-He PES. Differences in the experimental results for the two systems were used to provide details on the differences between the two PESs. DCSs and 2 q A moments are successfully recorded for the collisions of NO(A) with N2, O2 and CO as a function of rotational excitation of the unobserved partner. Trends in the DCSs for different degrees of rotational energy transfer to the unobserved collision partner are found to be consistent with collisions with the repulsive region of the PES leading to quenching collisions, rather than rotational energy transfer.