Order director fluctuations contribute to the low-field magnetic relaxation of dilute solutes in a nematic solvent

High-resolution magnetic relaxation dispersion (HR-MRD) is used to measure the field dependence of the 19F spin–lattice relaxation rates of C6F6 dissolved in the nematic phase of p-methoxybenzilidene–p-n-butylaniline (MBBA). HR-MRD permits measurement of low concentration solute spectral densities, which can be interpreted in terms of the various contributions to the spin Hamiltonian and dynamical models of molecular motion. In this case, C619F6 solute relaxation induced by magnetic dipole–dipole interactions reveal distinct components attributable to anisotropic rotational diffusion, and low-frequency order director fluctuations associated with the solvent.