Recently, Professor Han Yongchang from School of Physics, Dalian University of Technology, in collaboration with Professors Fu Bina and Zhang Donghui (Academician of CAS) from State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, has discovered the collision-induced roaming mechanism in another system (hydrogen atoms colliding with acetylene molecules) [Journal of Physical Chemistry Letters, 12, 4211 (2021)] after the previous study on the collision of hydrogen atoms with ethylene molecules [Chemical Science, 11, 2148 (2020)].

They report two novel roaming pathways for the H + C₂H₂→ H₂+ C₂H reaction by performing extensive quasiclassical trajectory calculations on a new, global, high-level machine learning-based potential energy surface. One corresponds to the acetylene-facilitated roaming pathway, where the H atom turns back from the acetylene + H channel and abstracts another H atom from acetylene. The other is the vinylidene-facilitated roaming, where the H atom turns back from the vinylidene + H channel and abstracts another H from vinylidene. The “double-roaming” pathways account for roughly 95% of the total cross section of the H₂+ C₂H products at the collision energy of 70 kcal/mol. These computational results give valuable insights into the significance of the two isomers (acetylene and vinylidene) in chemical reaction dynamics and also the experimental search for roaming dynamics in this bimolecular reaction.

The research result was published in The Journal of Physical Chemistry Letters with Fu Yanlin, a PhD student from School of Physics, as the first author and Professors Han Yongchang and Fu Bina as co-corresponding authors. This work was supported by the National Natural Science Foundation of China, the Key R&D Program of the Ministry of Science and Technology of the People’s Republic of China, and the Chinese Academy of Sciences.

Link to the paper: