Electron Spin-Lattice Relaxation at Defect Sites;E′Centers in Synthetic Quartz at 3 Kilo-Oersteds

Measurements of the spin-lattice relaxation time $T_1$ by the inversion-recovery technique are reported for two paramagnetic centers in quartz over a wide temperature range: from 1.3 to 250°K for the ${E_1}^{\prime }$ center, and from 2 to 80°K the ${E_2}^{\prime }$ center. The data, extending over several orders of magnitude in $T_1$, are interpreted in terms of cross relaxation, direct processes, and Raman processes. The dominant feature of the Raman relaxation is a temperature variation of about $T^3$, which is much slower than expected by standard theory.