Nuclear magnetic resonance relaxation studies of adsorbed water on porous glass of varying pore size

The proton magnetic resonance relaxation times of water adsorbed on porous glass of varying pore size has been measured as a function both of temperature in the range −91 to +92°C and of percentage relative humidity at 50 and 100%. Only the adsorbed water on the glass with the smallest pore size was amenable to a least squares fit of the Resing model for magnetic relaxation. The data indicate that the intracrystaline fluid at room temperature has about 10 times the average viscosity of bulk water but is four orders of magnitude less viscous than ice. With regard to mobility, the water in all the porous glasses studied behaved more like liquid than like ice but had a definite degree of ordering quite different from that of bulk water. A freezing phenomenon was only observed for the two larger pore-size glasses at about −16°C.