Proton Dipolar Spin–Lattice Relaxation in Nano-channels of Natrolite

The (1)H nuclear magnetic resonance (NMR) spectra and the dipolar spin–lattice relaxation time T(1D) for (1)H in the natural natrolite (Na(2)Al(2)Si(3)O(10)·2H(2)O) have been measured in the temperature range of 190–390 K. From the temperature transformations of (1)H NMR spectra, it follows that at T > 300 K, the diffusion of water molecules along the nano-channels is observed. From experimental T(1D) data, it follows that the 180° flip motion of the water molecules takes place in natrolite. At low temperature (T < 250 K), the dipolar interaction with paramagnetic impurities as a relaxation mechanism of (1)H nuclei becomes significant.