Deuteron line shape study of molecular order and conformation in the nematogens PAA and MBBA

Abstract
The deuteron fast Fourier transform (FFT) spectra of the ring deuterated nematogens para‐azoxyanisole (PAA‐d8) and p‐methoxybenzylidene pn‐butylaniline (MBBA‐d8) have been studied as a function of temperature. An interpretation of the spectra is presented. It is based on the assumption of nonequivalent deuterons, a twist angle φ between the planes of the benzene rings, and an asymmetry order parameter δ in addition to the usual nematic order parameter S. The temperature dependences of δ and φ have been obtained.