EFFECTS OF SLOW MOTION ON DEUTERON RELAXATION-TIME ANISOTROPY

When molecular motion occurs on multiple timescales, interpreting deut eron Zeeman relaxation times, T-1Z, yields ambiguous results, Simultan eous measurements of the orientation dependence of T-1Z and the quadru pole order relaxation time, T-1Q, are required to provide a more accur ate description. Processes with microsecond correlation times necessit ate analysis based on the stochastic Liouville equation. Relaxation of methyl deuterated bisphenol-A polycarbonate is considered as an illus tration, Numerous Redfield models are consistent with the T-1Z data, b ut their failure to reproduce the observed T-1Q anisotropy is characte ristic of slow motion. In complex systems where slow motion is ubiquit ous, it is essential that motional studies include measurement of both T-1Z and T-1Q anisotropies.