Susceptibility effects in unsaturated porous silica

Nuclear magnetic resonance proton line widths have been studied as the saturation level of water in a porous silica system is varied. Two silica samples were used with nominal pore sizes of 60 and 140 A. It was found that the line width increased with saturation level for both systems; this is consistent with the saturation process suggested by Allen et al. At low saturation levels the peak shift, from bulk water, increased with the saturation level reaching a maximum at filling factors of approximately 40% and 20% for the 60- and 140-A samples, respectively, after which point it began to decrease. Analysis is currently under way to try to model this system to determine whether these results are also consistent. It is anticipated that further analysis will give information on the pore morphology of the system.