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Ballistic molecular transport through two-dimensional channels

  • Date: 2018/05/15
  • Authors : A Keerthi, AK Geim, A Janardanan, AP Rooney, A Esfandiar, S Hu, SA Dar, IV Grigorieva, SJ Haigh, FC Wang, B Radha
  • Journal : arXiv preprint arXiv:1805.05835

Gas permeation through nanoscale pores is ubiquitous in nature and plays an important role in a plethora of technologies. Because the pore size is typically smaller than the mean free path of gas molecules, their flow is conventionally described by the Knudsen theory that assumes diffuse reflection (random-angle scattering) at confining walls. This assumption has proven to hold surprisingly well in experiment, and only a few cases of partially specular (mirror-like) reflection are known. Here we report gas transport through angstrom-scale channels with atomically-flat walls and show that surface scattering can be both diffuse or specular, depending on fine details of the surface atomic landscape, and quantum effects contribute to the specularity at room temperature. The channels made from graphene or boron nitride allow a helium gas flow that is orders of magnitude faster than expected …