Proton Spin—Lattice Relaxation in Barium Chlorate Monohydrate

The protonic spin—lattice relaxation times were measured as functions of orientation and temperature in a single crystal of Ba(ClO3)2·H2O. Pulse methods were used. The proton—proton vector was the axis of rotation of the crystal. Values of T1 were found within the range from 6 to 2400 sec. The orientational dependence was characteristic of intermolecular relaxation of the kind described by Holcomb and Pedersen. The temperature dependence was characteristic of 180° flipping motion of the H2O molecule whose activation energy was 5.0 kcal/mole. Sharp dips appeared in the values of T1 at certain orientations and temperatures. These probably are caused by cross relaxation between the protons and 35Cl nuclei.