@article {464, title = {2-Dimensional Xe-129 Exchange Nmr Measurements of Xenon Dynamics in Na-a Zeolite}, journal = {Zeolites and Related Microporous Materials: State of the Art 1994}, volume = {84}, year = {1994}, note = {Stud Surf Sci CatalPart a-CBd02eTimes Cited:3Cited References Count:21Studies in Surface Science and Catalysis}, pages = {519-526}, abstract = {Two-dimensional (2D) exchange NMR is a powerful tool for measuring the dynamics and energetics of adsorbed xenon atoms undergoing slow exchange between the alpha-cages of Na-A zeolite. In this proceedings, we present recently published results, as well as additional discussion and data obtained, using 2D Xe-129 NMR to determine rate coefficients for intercage xenon hopping and to correlate them with adsorption and activation energies. Variable-temperature experiments establish the activation energy for hopping between alpha-cages to be 60+/-10 kJ/mol. The dependence of these kinetic and thermodynamic quantities on xenon occupancy of the alpha-cages reflects the importance of intracage interactions on the behavior of the adsorbed guest molecules.}, keywords = {cavities}, isbn = {0167-2991}, url = {://WOS:A1994BD02E00063}, author = {Janicke, M. and Chmelka, B. F. and Larsen, R. G. and Shore, J. and Schmidt-Rohr, K. and Emsley, L. and Long, H. and Pines, A.} } @article {476, title = {Nmr-Study of Xenon Dynamics and Energetics in Na-a Zeolite}, journal = {Chemical Physics Letters}, volume = {214}, year = {1993}, note = {Chem Phys LettMd614Times Cited:56Cited References Count:22}, month = {Oct 29}, pages = {220-226}, abstract = {

For xenon atoms adsorbed in Na-A zeolite, electronic interactions cause shifts in NMR frequencies, resulting in a spectrum with discrete peaks from xenon atoms in cages with different xenon occupancies. Using two-dimensional exchange NMR, it is possible to determine the microscopic rates of intercage motion and to relate them to the adsorption and activation energies of the xenon atoms. The dependence of the adsorption energies on xenon cage occupancy reflects the importance of the intercage interactions and is directly related to the cage occupancy distribution. Variable temperature measurements yield an activation energy of about 60 kJ/mol for the transfer of a xenon from one cage to another.

}, keywords = {xe}, isbn = {0009-2614}, doi = {Doi 10.1016/0009-2614(93)90085-F}, url = {://WOS:A1993MD61400015}, author = {Larsen, R. G. and Shore, J. and Schmidt-Rohr, K. and Emsley, L. and Long, H. and Pines, A. and Janicke, M. and Chmelka, B. F.} }