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The absorption signals of protons and deuterons in bound and nonbound water molecules in the aqueous nickelous system were observed. From the PMR and DMR measurements, the hyperfine coupling constants were calculated and found to be (1.3±0.1)×105 and (2.0±0.2)×104 Hz, respectively. The spin density at the proton (and deuteron) nuclei was calculated to be (2.9±0.3)×10−5 electrons/a.u.3, in accordance with theoretical expectations. The rate constant at 298°K for the exchange of water was found to be 3×104 sec−1, and the activation energy 12 kcal/mole. The relaxation time of the electron at 243°K, assuming T1e =T2e was found to be 1.9×10−12 sec and the activation ernergy 0.8 kcal/mole. The temperature dependence of the proton transverse relaxation rate was studied. It is suggested that in the absence of chemical exchange the transverse relaxation rate is governed both by the relaxation of the nickelous unpaired electrons and by the diffusional motion of the water molecules. Methods of estimating the diffusional correlation time are discussed.

Whole frog sartorius and gastrocnemius muscles were incubated in Ringer's solutions, either unenriched or enriched with H2 7O or 2D20. Subsequently, the rates of transverse (l/T2) and of longitudinal (lTIT) nuclear magnetic relaxation were measured for 170, 2D, and 'H at room temperature and at 8.1 MHz.The ratio (T, /T2) for 170 was measured to be approximately 1.5-2.0, close to the value roughly estimated from the Larmor frequency dependence of 1/ T, alone over the range 4.3-8.1 MHz. On the other hand (T, /T2) for 2D and 'H were both measured to lie in the range 9-11. Insofar as the entire 170 signal was detected, the data indicate the presence of an exchange mechanism between the major fraction of intracellular water and a minor fraction characterized by enhanced rates of relaxation. Possible molecular mechanisms are presented.

A technique of double resonance in the laboratory frame is applied for the measurement of the pure quadrupole resonances of oxygen-17 in polycrystalline Ba(ClO3)2⋅H2 17O at 77°K. The spectrum comprises three frequency bands displaying fine structure that is interpreted in terms of the intramolecular dipolar interactions within the hydration water molecule. The experimental results are compared with theoretical spectra calculated for various geometries of the water molecule and relative orientations of the quadrupolar and dipolar interactions. It is not possible to obtain a complete agreement between the calculated and experimental spectra, since apparently not all predicted lines show experimentally. It is suggested that the transitions involving triplet eigenstates of the proton–proton dipolar interaction are not observed, presumably due to excessive line broadening. Based on this assumption a good fit with the experimental spectrum is obtained with the following parameters: e2qQ/h (17O) = (−7.61±0.01)MHz, η=0.94±0.01, proton–oxygen distance ROH= (0.99±0.02) Å, and the HOH angle 2ϑ=110°±2°. These results are discussed in terms of the electronic and geometric structure of the hydration water molecule.