Nuclear spin-lattice relaxation in ethylene and trans-dichloroethylene

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Abstract
Measurements have been made by pulse methods of the proton spin-lattice relaxation times T1 in solid ethylene from 60 °K to the melting point. The minimum value of T1 of 85±9 ms is compared with theoretical predictions for both correlated and uncorrelated motion of the molecules between two equilibrium positions, and it is shown that correlated motion is the more likely. Similar measurements have been made on trans-dichloroethylene, the minimum value of T1 being 27±03 s. The activation energies governing the two-fold reorientation process are 26±03 kcal mole-1 for ethylene and 36±02 kcal mole-1 for trans-dichloroethylene.