C-13 NMR INVESTIGATIONS OF SPIN-LATTICE RELAXATION IN 99-PERCENT C-13-ENRICHED DIAMONDS

The paper is devoted to investigations of spin-lattice relaxation proc esses in 99% C-13-enriched diamonds. Relaxation time measurements were performed as a function of orientation, magnetic field, and temperatu re. Both experimental results and theoretical discussion are presented . Multiexponential behavior of nuclear magnetization recovery was obse rved. There was found no significant influence of the diamond orientat ion on the nuclear spin-lattice relaxation. The field dependence of th e spin-lattice relaxation time was found to be proportional to the sec ond power of the magnetic field. The temperature measurements showed a weak increase of the spin-lattice relaxation time with decreasing tem perature. Possible mechanisms of impurity relaxation are considered an d compared with the experimental data. (C) 1998 Academic Press.