Nanoporous materials have the potential to be used as \emph{molecular sieves} to separate chemical substances in a mixture via selective adsorption and kinetic sieving. The separation of isotopologues is also possible via the so-called \emph{quantum sieving} effect: the different effective size of isotopologues due to their different ZPE. Here we compare the diffusion rates of Hydrogen and Deuterium in (8,0) Single Walled Carbon Nanotubes obtained through quantum dynamics methods. The diffusion channels obtained present important contributions from resonances connecting the potential wells. These resonances, which are more important for H2 than for D2, increase the low-temperature diffusivity of both isotopologues, but prevent the inverse kinetic isotope effect reported for similar nanostructured systems.
@article{arxiv.2011.01348,
title = {Competition of quantum effects in H$_2$ /D$_2$ sieving in carbon nanotubes},
author = {Manel Mondelo-Martell and Fermín Huarte-Larrañaga},
journal= {arXiv preprint arXiv:2011.01348},
year = {2021}
}
Comments
7 pages, 6 figures; Changed title; Re-formated for revtex; Clarified the discussion of the effect of below-barrier resonances; other minor changes