In this publication we report the first application of continuous flow hyperpolarized (HP) 129Xe techniques to studies of pore structure in ordered mesoporous materials. In particular, we report extensive 129Xe NMR chemical shift and spin-lattice relaxation time measurements of xenon adsorbed in mesoporous materials of different porosities and surface chemical composition. The use of HP Xe has allowed us to work at very low concentrations of xenon where the contribution of the Xe-Xe interactions is negligible and the observed 129Xe chemical shift reflects mainly interactions between the xenon atoms and the surface. Variable temperature measurements gave access to information on the adsorption parameters of xenon, and allowed us to follow the changes in these properties due to modification of the mesopore voids. Our 129Xe NMR data reveal a non-uniform porosity and irregular pore structure in contrast to N2 adsorption and TEM measurements that indicate regular nanoporous channels.
Revised: July 5, 2002 |
Published: June 13, 2002
Citation
Moudrakovski I.L., V.V. Terskikh, C.I. Ratcliffe, J.A. Ripmeester, L.Q. Wang, Y. Shin, and G.J. Exarhos. 2002.A Xe-129 NMR Study of Functionalized Ordered Mesoporous Silica.Journal of Physical Chemistry B 106, no. 23:5938-5946.PNNL-SA-35917.