State-to-state dynamics of the H(*)(n) + HD → D(*)(n') + H2 reactive scattering

The state-to-state dynamics of the H(*)(n) + HD → D(*)(n(')) + H2 reactive scattering at the collision energy of 0.5 eV have been carried out for the first time by using H-atom Rydberg tagging time-of-flight technique. Experimental results show that the angular distribution of the total H2 products presents clearly forward-backward asymmetric, which considerably differs from that of the corresponding H(+) + HD → D(+) + H2 reaction predicted by previously theoretical calculations. Such disagreement between these two processes suggests that the Fermi independent-collider model is also not valid in describing the dynamics of isotopic variants of the H(*) + H2 reaction. The rotational state distribution of the H2 products demonstrates a saw-toothed distribution with odd-j(') > even-j('). This interesting observation is strongly influenced by nuclear spin statistics.