Field-induced alignment of the nematic director: studies of nuclear magnetic resonance spectral oscillations in the limit of fast director rotation.

Time-resolved NMR spectroscopy is a powerful method to investigate field-induced rotation of the director in a nematic liquid crystal. The method requires that the director does not rotate significantly during the acquisition of the free induction decay and hence the NMR spectrum. We have extended the method to systems where this is not the case and the observed NMR spectra are now found to contain novel oscillatory features. To understand these oscillations, we have developed a model combining both director and spin dynamics. In addition to increasing the information content of the time-resolved NMR spectra, it also proves possible to determine the field-induced relaxation time from a single spectrum.