Spin-lattice relaxation in HF and NH3 doped ice and the outdiffusion of impurities

T₁ measurements have been done on pure, NH₃ doped and HF doped ice crystals. Three relaxation processes can be distinguished: a low temperature process, an extrinsic and an intrinsic process at high temperatures with activation energies of 0.08 eV, 0.35 eV and 0.62 eV respectively. Vested vacancies are proposed as defects effective in the low temperature process. The extrinsic high temperature process is due to vacancies which are formed by shifting a HF molecule to an interstitial site. Schottky defects are responsible for the intrinsic high temperature relaxation mechanism. Outdiffusion of HF is found to occur in concentration steps and at high concentrations by an interstitial mechanism.