WATER-SATURATED MESOPOROUS MCM-41 SYSTEMS CHARACTERIZED BY H-1-NMR

H-1 NMR measurements on a new family of mesoporous molecular sieves, d esignated MCM-41, saturated with water show abrupt changes in the sign al intensity of the water signal at specific temperatures, denoted as transition temperatures. A model equation is presented describing the intensity vs temperature behavior. Similar transition phenomena are al so observed in line width vs temperature. A linear relationship betwee n the spin-lattice relaxation rate (at -10 degrees C) and the first tr ansition temperature, as determined from the intensity measurements, i s found. This behavior is expected if it is assumed that the transitio n temperature can be predicted by Kelvin's equation and that the spin- lattice relaxation rate is proportional to the inverse of the pore rad ius, as previously reported in the literature.