Nuclear magnetic relaxation of adsorbed liquids in porous media containing paramagnetic impurity

G. G. Pimenov, B. I. Gizatullin

Institute of Physics, Kazan (Volga region) Federal University

Abstract: Pulse NMR was used to measure nuclear magnetic relaxation times of diethylene glycol molecules in porous Vycor glasses with a diameter of pores of 11 nm in the temperature interval of 99–342 К and of water molecules in bentonite (Dash-Salakhly deposits, Azerbaijan) at temperatures of 178–293 K. The concentration of diethylene glycol in porous glasses was close to the monolayer content of 11.1 wt %, and the water content in bentonite was kept at 22 wt %. In the range of low temperatures, spin-lattice relaxation time $T_1$ of diethylene glycol is determined by the relaxation times of an electron spin of impurity ions and the spin diffusion mechanism both in original and HCl-washed porous glasses. This work discusses nature of the strong difference in temperature dependences of relaxation times $T_1$ of diethylene glycol molecules in original and HCl-washed porous glasses. Spin-lattice relaxation of the water molecules depends on the paramagnetic ions concentration and the correlation time of the water molecular motions.

Keywords: NMR, relaxation time, porous glasses, bentonites, monolayer, correlation time.

UDC: 539.143.43+544.723.213

Received: 19.01.2011