A study was made of the paramagnetic F centers that were created by radiation doses that ranged over several orders of magnitude. Measurements were made of the electronic spin relaxation times of F centers, at low temperatures, by monitoring recovery of the magnetic circular dichroism of absorption and the temperature dependence of the 19F and 7Li nuclear spin relaxation times. The results indicated that nuclear spin relaxation was dominated by spin-diffusion limited paramagnetic relaxation. The electron spin correlation function was determined by the electronic spin–lattice relaxation. At 4 to 300K, the electron spin–lattice relaxation time was long when compared with the nuclear Larmor period. The temperature variation of the 19F and 7Li nuclear spin relaxation times indicated that the electron spin–lattice relaxation was dominated by phonon-F center interactions. At above 360K, an annealing process eliminated the F centers and their agglomerates.

Magnetic Resonance Investigation of the Dynamics of F Centers in LiF. T.Klempt, S.Schweizer, K.Schwartz, O.Kanert, D.Suter, U.Rogulis, J.M.Spaeth: Solid State Communications, 2001, 119[7], 453-8