Size effect in nuclear spin-lattice relaxation and atomic mobility for molten gallium particles

The spin-lattice relaxation rate of gallium isotopes in a melt was shown by NMR to increase considerably with a decrease in gallium particle size. The dominant relaxation mechanism of gallium embedded in an synthetic opal matrix changes from magnetic dipole to electrical quadrupole. The increase in the correlation time of atomic motion in gallium particles with a decrease in their size was estimated. For gallium in opal, the correlation time was found to increase by more than an order of magnitude. It was shown that a variation in atomic mobility becomes noticeable already in gallium particles about 5 µm in size.