Dipolar Relaxation of 7Li by Hindered Rotators NDxH3−x in Lithimn Hydrazinium Sulfate.
Parker, Robert S.
Schmidt, V. Hugo
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When a hindered rotation does not change the spatial charge distribution but merely permutes the locations of nuclear magnetic moments, the resulting spin-lattice relaxation of a nearby fixed nucleus is likely to be dipolar even if this nucleus has a quadrupole moment. The dipolar relaxation rate is props rtional to the average of γ2I(I + 1) for the rotating nuclei and accordingly varies linearly with percentage of deuteration. For 7Li in LiN2H5SO4 at 14 MHz the peak is 1.8 sec− at 185°K, while in 81% deuterated LiN2D5SO4 it is 4.2 times smaller, as predicted. The ND2 group deuterons also have a peak at this temperature, and all three curves show activation energy of about 0.19 eV, as found previously for protons and deuterons within rotating NH3 and ND3 groups.
Parker, Robert S, and V Hugo Schmidt. â€œDipolar Relaxation of 7Li by Hindered Rotators NDxH3âˆ’x in Lithimn Hydrazinium Sulfate.â€� Journal of Magnetic Resonance (1969) 6, no. 4 (April 1972): 507â€“515. doi:10.1016/0022-2364(72)90160-6.