Condensed phase isomerization through tunneling gateways
2022 | journal article. A publication with affiliation to the University of Göttingen.
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- Authors
- Choudhury, Arnab; DeVine, Jessalyn A.; Sinha, Shreya; Lau, Jascha A.; Kandratsenka, Alexander; Schwarzer, Dirk ; Saalfrank, Peter; Wodtke, Alec Michael
- Abstract
- Quantum mechanical tunnelling describes transmission of matter waves through a barrier with height larger than the energy of the wave1. Tunnelling becomes important when the de Broglie wavelength of the particle exceeds the barrier thickness; because wavelength increases with decreasing mass, lighter particles tunnel more efficiently than heavier ones. However, there exist examples in condensed-phase chemistry where increasing mass leads to increased tunnelling rates2. In contrast to the textbook approach, which considers transitions between continuum states, condensed-phase reactions involve transitions between bound states of reactants and products. Here this conceptual distinction is highlighted by experimental measurements of isotopologue-specific tunnelling rates for CO rotational isomerization at an NaCl surface3,4, showing nonmonotonic mass dependence. A quantum rate theory of isomerization is developed wherein transitions between sub-barrier reactant and product states occur through interaction with the environment. Tunnelling is fastest for specific pairs of states (gateways), the quantum mechanical details of which lead to enhanced cross-barrier coupling; the energies of these gateways arise nonsystematically, giving an erratic mass dependence. Gateways also accelerate ground-state isomerization, acting as leaky holes through the reaction barrier. This simple model provides a way to account for tunnelling in condensed-phase chemistry, and indicates that heavy-atom tunnelling may be more important than typically assumed.
- Issue Date
- 2022
- Journal
- Nature
- Organization
- Institut für Physikalische Chemie ; Max-Planck-Institut für Multidisziplinäre Naturwissenschaften
- ISSN
- 0028-0836
- eISSN
- 1476-4687
- Language
- English