Interference microscopy as a technique for directly measuring intracrystalline transport diffusion in zeolites

A detailed description of the application of interference microscopy to mea sure intracrystalline transport diffusion in zeolites is given. It is demon strated how phase differences as the primary data of interference microscop y may be transferred into information about intracrystalline concentration profiles and their evolution with time. As an example, molecular uptake of methanol in zeolite NaCaA is considered. The concentration profiles along t he crystallite diagonal are given at different instants of time. Finally, t he range of diffusivities obtained by applying the microscopic version of F ick's second law to the concentration data is presented. (C) 1999 Elsevier Science B.V. All rights reserved.