SELECTIVE INVERSION INVESTIGATIONS OF SLOW MOLECULAR-MOTION IN SOLID-STATE DEUTERON NMR-SPECTROSCOPY

Deuteron selective inversion experiments are reported for polycrystall ine dimethyl sulfone-d(6) as a function of temperature from 288 to 333 K. Double sideband modulation was used to achieve efficient off-reson ance orientation-selective inversion. Fitting the selective inversion- recovery curves to two-site jump equations yields the motional rate. T emperature dependent jump rates, obtained from both selective inversio n and deuteron quadrupole echo lineshapes, give an activation energy E (a) = 86.5 +/- 1.4 kJ mol(-1) and a frequency factor In(A)= 39.2 +/- 0 .5. These values differ significantly from those of earlier C-13 lines hape studies. At 298 K, variable power excitation was used to determin e the underlying orientation dependent homogeneous linewidth, which is predominantly dipolar. The temperature dependence of the homogeneous linewidth is a sensitive indicator of large angle jump motion in the r ange 10(3)-10(4) s(-1).