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.