Segmental mobility as a function of an external (e.g. elec.) perturbation of liq. crystals [LC] and liq. crystal polymers [LCP] was studied using FTIR methods. Step-scan FTIR spectroscopy was used for time-resolved measurements down to the sub-microsecond range of orientation-relaxation of LC's and LCP's in an elec. field. The flexible aliph. segments and the rigid mesogens of the LC mols. reorient synchronously. In the case of nematic LCP's and ferroelec. LCP's, only a small part of the spacer moves in phase with the mesogen, whereas the rest of the mol. is more or less stable during the switching of nematic LCP's or poling of ferroelec. LCP's.