title: Transport in Nanoporous Materials Including MOFs: The Applicability of Fick's Laws.
abstract: Diffusion in nanoporous host-guest systems is often considered to be too complicated to comply with such "simple" relationships as Fick's first and second law of diffusion. However, it is shown herein that the microscopic techniques of diffusion measurement, notably the pulsed field gradient (PFG) technique of NMR spectroscopy and microimaging by interference microscopy (IFM) and IR microscopy (IRM), provide direct experimental evidence of the applicability of Fick's laws to such systems. This remains true in many situations, even when the detailed mechanism is complex. The limitations of the diffusion model are also discussed with reference to the extensive literature on this subject.
authors.affiliation: Department of Interface Physics, University of Leipzig, Linnéstrasse 5, 04103 Leipzig (Germany).
authors.forename: Tobias
authors.initials: T
authors.lastname: Titze
authors.affiliation: Department of Interface Physics, University of Leipzig, Linnéstrasse 5, 04103 Leipzig (Germany).
authors.forename: Alexander
authors.initials: A
authors.lastname: Lauerer
authors.affiliation: Institute of Functional Interfaces, Karlsruher Institut für Technologie, Karlsruhe (Germany).
authors.forename: Lars
authors.initials: L
authors.lastname: Heinke
authors.affiliation: Department of Interface Physics, University of Leipzig, Linnéstrasse 5, 04103 Leipzig (Germany).
authors.forename: Christian
authors.initials: C
authors.lastname: Chmelik
authors.affiliation: Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, (USA).
authors.forename: Nils E R
authors.initials: NE
authors.lastname: Zimmermann
authors.affiliation: Department of Chemical Reaction Engineering, Hamburg University of Technology, Hamburg (Germany).
authors.forename: Frerich J
authors.initials: FJ
authors.lastname: Keil
authors.affiliation: Chemical and Biological Engineering, University of Maine, Orono, (USA).
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Ruthven
authors.affiliation: Department of Interface Physics, University of Leipzig, Linnéstrasse 5, 04103 Leipzig (Germany). kaerger@physik.uni-leipzig.de.
authors.forename: Jörg
authors.initials: J
authors.lastname: Kärger
mesh_terms: D001692:Biological Transport; D009682:Magnetic Resonance Spectroscopy; D008853:Microscopy / Q000379:methods; D008956:Models, Chemical; D049329:Nanostructures; D016062:Porosity
keywords: Fick’s laws; diffusion; metal-organic frameworks; nanoporous materials; zeolites