Résumé

Stereodynamics experiments of Ne(3P2) reacting with Ar, Kr, Xe, and N2 leading to Penning and associative ionization have been performed in a crossed molecular beam apparatus. A curved magnetic hexapole was used to state-select and polarize Ne(3P2) atoms which were then oriented in a rotatable magnetic field and crossed with a beam of Ar, Kr, Xe, or N2. The ratio of associative to Penning ionization was recorded as a function of the magnetic field direction for collision energies between 320 cm−1 and 500 cm−1. Reactivities are obtained for individual states that differ only in Ω, the projection of the neon total angular momentum vector on the inter-particle axis. The results are rationalized on the basis of a model involving a long-range and a short-range reaction mechanism. Substantially lower probability for associative ionization was observed for N2, suggesting that predissociation plays a critical role in the overall reaction pathway.

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