Spin-lattice relaxation of radicals in the solid state. Part 3

Some causes of spin-lattice relaxation in the solid state are considered. It is found that anisotropic hyperfine interaction can make an appreciable contribution to the spin-lattice relaxation time, which becomes dependent on the orientation of the radical relative to the external field and on the number of HS components. There is no appreciable contribution from frequency modulation of the vibrations (of the radical as a whole or purely intramolecular) caused by the lattice vibrations.