Dynamic of water molecules in natrolite

Molecular mobility of water molecules has been investigated in the natural zeolite natrolite (Na2Al2Si3O10 ·2H2O) by 1H NMR. Spin-lattice relaxation times in the laboratory and rotating frames (T1 and T1-) have been measured as a function of temperature for a polycrystalline sample. It has been shown that the spin-lattice relaxations times of 1H are governed by the translation motions of water molecules in the natrolite pores. From experimental T1 data it follows that at T > 286 K the diffusion of water molecules along channels parallel to the c axis is observed. From experimental T1 data it follows that at T > 250 K the diffusion of water molecules in transversal channels of natrolite is observed also. At low temperature (T < 250 K) the dipolar interaction with paramagnetic impurities (presumably with Fe3+ ions) become significant as a relaxation mechanism of 1H nuclei