On the detection of second-order director fluctuations at a standard high field by spin-spin relaxation

We report measurements of the deuteron spin-spin relaxation time T2 in the nematic phase of p-methoxybenzylidene-p-n-butylaniline using the quadrupolar echo pulse train in a magnetic field of 7 T. The derived zero-frequency spectral densities J0(0) at different carbon sites, unlike the J1(Ω0) and J2(2Ω0), could not be interpreted using molecular reorientation and internal bond rotations in the butyl chain. It is shown that experimental T2 data at a high magnetic field could be used to gain information on second-order director fluctuations.