Direct NMR observation of rotational freeze-out in the smecticCphase

We report here a simple and direct observation that the molecular long axis is not, on the average, a rotation axis for the entire molecule in the smectic $C$ phase (rotational freeze-out). This observation is made in the compound 4-$n$-heptyl-$d_{15}$-oxybenzoic acid-$d_1$ where experiment clearly shows that the principal axes of the time-averaged deuterium quadrupole interactions at specific sites of the hydrocarbon chain are not all parallel, demonstrating that they do not share a common axis of rotation.