NMR study of 3He adsorbed on exfoliated graphite

The present work has been carried out to investigate the dynamic properties of 3 He film adsorbed on an exfoliated graphite substrate, using pulsed NMR techniques. It has been found that the dipolar interaction is the dominant mechanism for the spin relaxation, although the effect of the grafoil local fields can not be ignored. The spin-lattice relaxation time T1 and the spin-spin relaxation time T2 which characterize the spin system were determined.The study has been concentrated on two phases. The registered phase and the solid phase. Some data were taken at the mixed phase which lies between them. Both relaxation times were determined as functions of monolayer capacity, frequency, temperature and spin orientations. For temperatures less than 2 K, the spins exhibit quantum motion behaviour. The frequency of this motion was determined and was found to be inversely proportional to the spin density.At the registered phase, the activation temperature was determined, where it was a maximum corresponding to perfect registry. Special attention was given to the T1 data at the minima in the solid phase since there the frequency of the motion is comparable to the Larmor frequency.