Comparison of the 129Xe NMR Chemical Shift with Simulation in Zeolite Y

Abstract

We report quantitative agreement between Monte Carlo simulation and the experimental NMR chemical shift of 129Xe adsorbed in the supercages of zeolite Y. This agreement supports previous assertions, originating from Ripmeester and Fraissard, that the Xe shift can in principle provide a sensitive measure of the structure imposed on Xe by the three-dimensional potential field provided by the crystal structure of the zeolite. Up to a loading of 7 Xe/cage at 300 K, we verify that the linear rise of shift with loading is due solely to Xe−Xe interaction. We also find excellent agreement at 144 K between simulation and the nonlinear experimental data of Cheung et al. The nonlinear dependence of shift on loading arises both from repulsive Xe−Xe and from repulsive Xe−O interactions. Finally we verify that the effect of temperature on the shift at zero loading can be related to the change of Xe−O pair correlation function at short separations.