Proton Spin—Lattice Relaxation in Liquid Chloroform

The proton spin—lattice relaxation time has been measured over the temperature range $\text{−54−90°}\mathrm{C}$ at 60 MHz in liquid chloroform. At 65°C a minimum relaxation rate is observed and from this the important contributions to the relaxation rate have been estimated at 65°C and a series of lower temperatures. It is shown that the intermolecular dipolar relaxation rate dominates at the lower temperatures but the intramolecular contribution becomes increasingly important with increasing temperature and dominates above about 55°C. The spin—rotational relaxation rate is relatively significant and is larger than the intramolecular dipolar term over the entire temperature range studied. The intermolecular dipolar relaxation rates are in reasonable agreement with values calculated with use of translational correlation times estimated from the self‐diffusion coefficients at each temperature. The activation energies for the various relaxation mechanisms are reported.