DEUTERIUM NMR-STUDY OF ORIENTATIONAL ORDER IN CAMPHOR

This investigation of the 2H NMR absorption profile of D-camphor-3,3-d2 demonstrates that the solid 1 (cubic)-solid II (rhombohedral) phase transition, through which complete rotational disorder was thought to be preserved, is actually accompanied by the onset of weakly preferred orientations. It is shown that throughout the temperature range of solid II, the spectra can be simulated by introducing temperature-dependent average order parameters analogous to those of liquid crystals and other partially ordered structures. Relaxation rates and angular correlation times are also presented for solid I. © 1979.