The dynamical Renner–Teller effect. II. Rotationally inelastic scattering of NCO(X̃ 2Π,0010)+He

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Abstract
State-resolved integral cross sections for the inelastic scattering of the Hund’s case (a) radical NCO(X̃ 2Π) by He have been measured in a crossed-beam apparatus. Two different types of measurements are reported: (1) state-resolved integral cross sections at fixed collision energies from 0.94–3.05 kcal mol−1 and (2) the collision energy dependence of state-specific product states for both 2Π3/2 and 2Π1/2 spin–orbit states of NCO(X̃ 2Π,0010). As in a preliminary account of this work for E0=3.74 kcal mol−1 [J. Phys. Chem. 91, 9630 (1991)], herein referred to as part I, dramatically different rotational level distributions were found for spin–orbit conserving or changing collisions. It is argued that this behavior and many other observations on this system are generic to the inelastic scattering of Hund’s case (a) 2Π radicals. A conceptual framework to understand these results is elucidated in detail. The direct connection between the experimental observables and the Hund’s case classification is made for the inelastic scattering of radicals. This connection can be viewed as a dynamical consequence of the Renner–Teller effect.