DIELECTRIC-RELAXATION OF TRIMETHYLPHOSPHATE IN ITS PURE LIQUID-STATE AND IN MESITYLENE SOLUTION

The dielectric loss spectrum of trimethylphosphate, OP(OCH3)(3)(TMP), has been measured up to 72 GHz for concentrations ranging between 0.5 mole percent in mesitylene to pure TMP at 20 degrees C. It is interpreted in terms of whole molecule reorientational motion mixed with substantial contributions from intramolecular motion. Most spectral parameters change only little with concentration, but a superlinear increase in the total relaxation strength with concentration (that is, an increase in the apparent dipole moment) is a remarkable feature. This points to a certain preference for specific conformations.