Article

Direct mapping of the angle-dependent barrier to reaction for Cl + CHD3 using polarized scattering data

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Abstract

The transition state, which gates and modulates reactive flux, serves as the central concept in our understanding of activated reactions. The barrier height of the transition state can be estimated from the activation energy taken from thermal kinetics data or from the energetic threshold in the measured excitation function (the dependence of reaction cross-sections on initial collision energies). However, another critical and equally important property, the angle-dependent barrier to reaction, has not yet been amenable to experimental determination until now. Here, using the benchmark reaction of Cl + CHD3(v1 = 1) as an example, we show how to map this anisotropic property of the transition state as a function of collision energy from the preferred reactant bond alignment of the backward-scattered products—the imprints of small impact-parameter collisions. The deduced bend potential at the transition state agrees with ab initio calculations. We expect that the method should be applicable to many other direct reactions with a collinear barrier.

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Acknowledgements

The authors thank J.-S. Lin and O. Tkac for assisting with some imaging acquisitions. This work was supported by Academia Sinica and the Minister of Science and Technology of Taiwan (MOST-105-2113-M-001-019-MY3). F.W. also acknowledges support from the National Nature Science Foundation of China (grants 21322309 and 21673047) and the Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning. G.C. thanks the Scientific Research Fund of Hungary (PD-111900) and the Bolyai Research Scholarship for financial support and the National Information Infrastructure Development Institute for computer resources.

Author information

Author notes

    • Huilin Pan
    •  & Fengyan Wang

    These authors contributed equally to this work.

Affiliations

  1. Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, PO Box 23-166, Taipei 10617, Taiwan

    • Huilin Pan
    • , Fengyan Wang
    •  & Kopin Liu
  2. Department of Chemistry, Collaborative Innovation Centre of Chemistry for Energy Materials, Fudan University, Shanghai 200433, China

    • Fengyan Wang
  3. Department of Physical Chemistry and Materials Science, Institute of Chemistry, University of Szeged, Rerrich Béla tér 1, Szeged H-6720, Hungary

    • Gábor Czakó
  4. Department of Physics, National Taiwan University, Taipei 10617, Taiwan

    • Kopin Liu

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Contributions

K.L. conceived and designed the experiments. H.P. and F.W. performed the experiments and analysed the data. G.C. performed theoretical calculations. All authors discussed the results and commented on the manuscript. K.L. wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Fengyan Wang or Gábor Czakó or Kopin Liu.

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