Correlating PFG NMR and IR Diffusion Measurements in Porous Glasses

1. Introduction Molecular diffusion is among the famous topics of current research on nanoporous materials [1]. Diffusion of molecules in porous media can be measured by a large variety of experimental methods. However, diffusivities measured with different techniques for the same system vary in several zeolitic systems over more than two orders of magnitude [2]. In many cases the origin of this discrepancy still remains unclear, even after 30 years of zeolite research. Hence, demonstrating agreement between results measured by different techniques on identical material assumes an important step in the concerted efforts to solve the existing, formidable puzzle about molecular transport in zeolites and other nanoporous materials. With the rise of a new class of nanoporous glasses now ideal conditions are provided to solve this challenging task. In the present work we show the perfect agreement of diffusivities yielded by two prominent representatives of experimental techniques, namely pulsed field gradient (PFG) NMR and IR Microscopy (IRM).