NMR methods of studying orientational order in the liquid crystalline and isotropic phases of mesogenic samples

The understanding of how to describe the orientational order of the molecules in liquid crystalline phases, and in the isotropic phase formed by mesogens, has undergone considerable development in the past 25 years; this progress is reviewed. In parallel with the theoretical developments it has also been shown that NMR spectroscopy plays a unique role in the measurement of the orientational order of the molecules, and it is explained how biaxial ordering can be characterized for rigid molecules, and how the conformationally-dependent order parameters necessary for flexible molecules can be obtained.