Measurement of xenon distribution statistics in Na-A zeolite cavities

Abstract

$^{129}\mathrm{Xe}$ NMR spectroscopy has been used to probe directly the distribution of xenon atoms confined in atomic-size Na-A zeolite cavities. For mean xenon occupancies less than about three Xe atoms per \ensuremath{\alpha}-cage, the guest populations are well described by binomial statistics. At higher guest loadings the finite volumes of the xenon atoms become significant, as reflected by a fit of the experimental populations with a hypergeometric distribution. The data and hypergeometric analysis indicate a maximum occupancy of seven Xe atoms/cage. At the highest xenon loadings the experimental distribution is narrower than hypergeometric.