The H+D2 reaction: Quantum-state distributions at collision energies of 1.3 and 0.55 eV

Abstract
We have studied the H+D2 →HD+D reaction using thermal D2 (∼298 K) and translationally hot hydrogen atoms. Photolysis of HI at 266 nm generates H atoms with center‐of‐mass collision energies of 1.3 and 0.55 eV, both of which are above the classical reaction barrier of 0.42 eV. The rovibrational population distribution of the molecular product is measured by (2+1) resonance‐enhanced multiphoton ionization (REMPI). The populations of all energetically accessible HD levels are measured. Specifically, we observe HD(v=0, J=0–15), HD(v=1, J=0–12), and HD(v=2, J=0–8). Of the available energy, 73% is partitioned into product translation, 18% into HD rotation, and 9% into HD vibration. Both the rotational and vibrational distributions are in remarkably good agreement with quasiclassical trajectory (QCT) calculations, though the calculated rotational distributions are slightly too hot. We discuss factors contributing to the success of the QCT calculations.

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