XE-129 NMR LINEWIDTHS AS INDICATORS OF SPATIAL INHOMOGENEITIES IN ZEOLITES

The widths of the Xe-129 nuclear magnetic resonance (NMR) lines of xen on in zinc- and cadmium-exchanged zeolites NaY and HY were measured at ambient temperature as a function of the xenon gas equilibrium pressu re. It is demonstrated that the observed values of the linewidths as w ell as their quite different dependence on pressure can be explained o n the basis of a theoretical approach which traces back the origin of line broadening to inhomogeneous spatial distributions of transition m etal cation sites interacting strongly with the encaged xenon atoms.