Paramagnetic Mn2+ ions were incorporated in silica gel during the preparation of the sol. Doped silica xerogels were obtained by heat treatment at different temperatures and studied by Si-29 and Xe-129 nuclear magnetic resonance (NMR) experiments. Comparison between Si-29 NMR magic angle spinning (MAS) spectra of doped and undoped xerogels showed that there is a significant effect of the paramagnetic probe on Q(2), Q(3) and Q(4) peaks. Reduction of the Si-29-T-1 relaxation time in the presence of the Mn2+ probe was observed. Xe-129 NMR spectra were recorded on the xerogels at variable Xe pressures. Results were consistent with 29Si NMR data and confirmed the localization of the paramagnetic probe in surface sites as shown by electron paramagnetic resonance (EPR) of Mn2+. (C) 1998 Elsevier Science B.V. All rights reserved.
|Journal||Journal of Non-Crystalline Solids|
|State||Published - 1998|