Tracking the structural change of the predissociating molecule near the transition state.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39753540.
- Also identified by DOI 10.1038/s41467-024-55249-z and PMC identifier 11698995.
- Licence recorded as CC BY-NC-ND.
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Abstract
Despite its profound significance, the molecular structural changes near the transition state, driven by the vibronic coupling, have remained largely unexplored, leaving a crucial aspect of chemical reactions shrouded in uncertainty. Herein, the dynamical behavior of the reactive flux on the verge of chemical bond breakage was revealed through the spectroscopic characterization of a large amplitude vibrational motion. Highly excited internal rotor states of S<sub>1</sub> methylamine (CH<sub>3</sub>ND<sub>2</sub>) report on the structural change as the molecule approaches the transition state, indicating that the quasi-free internal rotation is strongly coupled to the reaction coordinate as their energies near the maximum of the reaction barrier for the N-D chemical bond predissociation. Energy-dependent behavior of the rate constant perfectly correlates with that of the molecular structural change in the N-D bond length, providing unprecedented crucial information about how vibrational energy flows into the reaction coordinate on the adiabatic potential energy surfaces.