NMR relaxation rate measurements are reported for protons in aqueous nitroxide solutions over the frequency range from 0.01 to 20 MHz. A complete relaxation dispersion curve is observed that is analyzed in terms of dynamical models for the interaction between the solvent and solute. Both translational and rotational motions contribute to the relaxation behavior, although the translational contribution is dominant. Dipolendash;dipole interactions are sufficient to account for the data over this frequency range. At 298 K translational motions account for 75percnt; for the relaxation, and are characterized in the present analysis by correlation time of 73 ps and 2.5 Aring; as the distance of closest approach. The small rotational term requires a 22 ps correlation time and an interdipole separation of 2.1 Aring;.
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