The shape of the NMR spectrum and the spin-lattice relaxation in aqueous suspensions of charcoals

H-1 NMR spectra of aqueous suspensions of charcoals used in the oximetry of living tissues and spin-lattice relaxation times T-1 of individual lines o f the spectra were measured. The spectra involve two lines. The higher inte nsity line was assigned to protons of water molecules located in the space between charcoal particles and in the macropores of these particles, whose volume was estimated at about half the volume of the charcoal particles. Th e dependence of T-1 for this line on the particle size L was used for estim ating the diameter of the macropores and the relaxation time T-1,T-s of pro tons of water molecules in the surface layer. The second line, having a rel ative integral intensity of approximate to0.04, was shifted towards the hig h-field region by approximate to5 ppm. The time T-1 (approximate to 50 mus) for this line did not depend on L. This line was assigned to protons of wa ter molecules located in charcoal micropores. The disintegration in the str ucture of hydrogen bonds resulted in a shift of the NMR signal and a dramat ic lowering of the freezing point of water in the micropores. The second li ne occurred in spectra of suspensions cooled to -80 degreesC, whereas the f irst line disappeared in the range from 0 to -10 degreesC.