NMR MEASUREMENT OF PORE STRUCTURE

Several different NMR experiments are described for obtaining information about pore sizes and the physical chemistry of molecules in restricted geometries. These methods include Xe-129 chemical shifts, Xe-129 freezing, N-15(2) freezing, and (CO2)-C-13 freezing in pores. We conclude that care must be taken in the application of the mean free path model relating Xe-129 chemical shifts and pore diameters. The freezing experiments are interesting in providing information about the state of small molecules in pores but they do not yield quantitative pore size information in themselves.