State-to-state reactive dynamics of H + HD→H₂ + D at 2.20 eV

As the simplest neutral triatomic reaction system, the H + H₂ bimolecular reaction and its isotope variants are critically important for understanding elementary chemical reactions at the microscopic level. A high-resolution crossed molecular beams method was used in this work to explore the H + HD→H₂ + D elementary chemical reaction at a collision energy of 2.20 eV. The product D atoms were detected using the 1 + 1' (vacuum ultraviolet and ultraviolet laser) D-atom near-threshold ionization technique. Differential cross sections with vibrational and rotational state resolutions were experimentally acquired, covering the full scattering angular range. Particularly, fast forward oscillations were presented at several rovibrational states, such as v' = 0, j' = 10 and v' = 1, j' = 5. Our analysis shows that scattering partial waves close to J = 36 mainly contribute to the oscillatory structures. Moreover, the branching ratios of the odd j' and even j' were also derived, revealing that the rotational populations of the H₂ (v' = 0) co-product strongly depend on the nuclear spin statistics.