Observation of the isotope effect in sub-kelvin reactions
| Autor: | Yuval Shagam, Edvardas Narevicius, Piotr S. Żuchowski, Sasha Gersten, Alon B. Henson, Etay Lavert-Ofir, Jacek Kłos, Julia Narevicius |
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| Rok vydání: | 2014 |
| Předmět: | |
| Zdroj: | Nature Chemistry. 6:332-335 |
| ISSN: | 1755-4349 1755-4330 |
| Popis: | Quantum phenomena in the translational motion of reactants, which are usually negligible at room temperature, can dominate reaction dynamics at low temperatures. In such cold conditions, even the weak centrifugal force is enough to create a potential barrier that keeps reactants separated. However, reactions may still proceed through tunnelling because, at low temperatures, wave-like properties become important. At certain de Broglie wavelengths, the colliding particles can become trapped in long-lived metastable scattering states, leading to sharp increases in the total reaction rate. Here, we show that these metastable states are responsible for a dramatic, order-of-magnitude-strong, quantum kinetic isotope effect by measuring the absolute Penning ionization reaction rates between hydrogen isotopologues and metastable helium down to 0.01 K. We demonstrate that measurements of a single isotope are insufficient to constrain ab initio calculations, making the kinetic isotope effect in the cold regime necessary to remove ambiguity among possible potential energy surfaces. |
| Databáze: | OpenAIRE |
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