SPIN-LATTICE RELAXATION OF THE HYDROGEN-ATOM IN A FUSED QUARTZ

The paramagnetic spin-lattice relaxation of hydrogen atoms in gamma-ir radiated fused quartz at 77 K was measured by an electron spin echo me thod. The relaxation was induced by dipole interactions between electr on spins, so that the relaxation rate increased with the concentration of the hydrogen atoms. The observed relaxation was compared with theo retical one in which the spin diffusion and the phonon-induced simulta neous transition of the electron spin state and the local vibrational state of the hydrogen atoms in trapping sites were taken into account. The theoretical relaxation behavior was in perfect accordance with th e observed one. The relaxation was ten orders of magnitude accelerated by the spin diffusion of the hydrogen atoms, which indicates that the spin diffusion plays a significant role on the spin-lattice relaxatio n of paramagnetic species with small g anisotropy.