NMR-STUDY OF XENON DYNAMICS AND ENERGETICS IN NA-A ZEOLITE

For xenon atoms adsorbed in Na-A zeolite, electronic interactions caus e shifts in NMR frequencies, resulting in a spectrum with discrete pea ks from xenon atoms in cages with different xenon occupancies. Using t wo-dimensional exchange NMR, it is possible to determine the microscop ic rates of intercage motion and to relate them to the adsorption and activation energies of the xenon atoms. The dependence of the adsorpti on energies on xenon cage occupancy reflects the importance of the int ercage interactions and is directly related to the cage occupancy dist ribution. Variable temperature measurements yield an activation energy of about 60 kJ/mol for the transfer of a xenon from one cage to anoth er.