Diffusion of H2 and D2 Confined in Single-Walled Carbon Nanotubes: Quantum Dynamics and Confinement Effects

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• 作者：Manel Mondelo-Martell ; Fermín Huarte-Larrañaga
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：August 25, 2016
• 年：2016
• 卷：120
• 期：33
• 页码：6501-6512
• 全文大小：550K
• 年卷期：0
• ISSN：1520-5215

文摘

We present quantum dynamics calculations of the diffusion constant of H₂ and D₂ along a single-walled carbon nanotube at temperatures between 50 and 150 K. We calculate the respective diffusion rates in the low-pressure limit by adapting well-known approaches and methods from the chemical dynamics field using two different potential energy surfaces to model the C–H interaction. Our results predict a usual kinetic isotope effect, with H₂ diffusing faster than D₂ in the higher temperature range but a reverse trend at temperatures below 50–70 K. These findings are consistent with experimental observation in similar systems and can be explained by the different effective size of both isotopes resulting from their different zero-point energy.