9458017 Grey Adsorption sites for monomethylamine and pyridine on acidic zeolites, and for hydroflourocarbons on basic zeolites, will be probed using double and triple resonance MAS NMR experiments. Distances between nuclei at surface sites and on the adsorbed molecules will be measured in order to determine the structure of the adsorbate/adsorbent complexes. %%% ***