Nuclear double resonance cross-relaxation in solid NH4NO3

The double resonance cross-relaxation rates between H1 and N15 in powders of solid NH4NO3 were measured as a function of the rotating field magnitude H1. The cross-relaxation rate, obtained in a low dipolar temperature state, exhibits an exponential dependence on H1. This result shows that the previous assumptions of a Lorentzian correlation function for the dipolar fluctuations introduced by McArthur et al., is a correct approximation in this case, too. An attempt was made to include the molecular motion effects on the cross-relaxation rate. (author)