DIFFUSION OF ATOMIC-HYDROGEN IN ICE-IH

We report new measurements of EPR spin relaxation times T1 and T2 for H atoms in hexagonal ice at -6-degrees-C. We find T1 = 23 +/- 3 mus, a nd T2 = 6.9 +/- 1.0 mus at this temperature, in good agreement with ex pectation based on previous experiments. Motional correlation times ha ve been calculated from these values and from previous T2 measurements for H and D atoms in isotopically mixed ice. The hopping rate deduced - 2.8 x 10(10) s-1 near the crystal melting point, implies a diffusio n rate of H atoms in ice nearly as fast as occurs in liquid water.