Unprecedented Insight into Diffusion by Monitoring the Concentration of Guest Molecules in Nanoporous Host Materials

Abstract

How many guests? Interference microscopy is used to monitor the concentration of guest molecules in a ferrierite zeolite. The micropore diffusivities are determined as a function of loading through the microscopic application of Fick's second law. This method can be used to study isotropic and anisotropic diffusion, as well as to locate and quantify surface barriers and internal defects.

Analysis of thermal effects in infrared and interference microscopy: n-Butane-5A and methanol–ferrierite systems

“…This mean concentration (i.e., the total amount of mole cules in beam direction) may be deduced by analyzing the interference patterns after superposition of these two beams. The potential of the method to shed unprecedented insight into the internal diffusion transport has been recently discussed by Kärger et al [5].…”

Transport in Nanoporous Materials Including MOFs: The Applicability of Fick’s Laws

“…during uptake and release) concentrations vary with time and space. The recent advent of microimaging [23,24,25] has made it possible to record the evolution of such profiles with unprecedented accuracy. Figure 1a shows the concentration profiles of cyclohexane, determined in this way during uptake by a porous glass.…”

The surface barrier phenomenon at the loading of metal-organic frameworks

“…First hints regarding the microscopic origin of these strong sample-to-sample variations have been provided by studies using interference microscopy 16 and infrared microimaging 17 . Analysis of intracrystalline concentration profiles found that so-called surface barriers may influence the uptake of molecules into these porous materials.…”