Assessing guest diffusivities in porous hosts from transient concentration profiles.
Using the short-chain-length alkanes from ethane to n-butane as guest molecules, transient concentration profiles during uptake or release (via interference microscopy) and tracer exchange (via IR microimaging) in Zn(tbip), a particularly stable representative of a novel family of nanoporous materials (the metal organic frameworks), were recorded. Analyzing the spatiotemporal dependence of the profiles provides immediate access to the transport diffusivities and self-diffusivities, yielding a data basis of unprecedented reliability for mass transfer in nanoporous materials. As a particular feature of the system, self- and transport diffusivities may be combined to estimate the rate of mutual passages of the guest molecules in the chains of pore segments, thus quantifying departure from a genuine single-file system.
Heinke
Lars
L
Faculty of Physics and Geosciences, Department of Interface Physics, University of Leipzig, Linnéstrasse 5, 04103 Leipzig, Germany.
Tzoulaki
Despina
D
Chmelik
Christian
C
Hibbe
Florian
F
van Baten
Jasper M
JM
Lim
Hyuna
H
Li
Jing
J
Krishna
Rajamani
R
Kärger
Jörg
J