QENS and NMR Investigation of Molecular DIF Fusion in the Nematic Phase of EBBA

Abstract

In this paper we present a combined Quasi Elastic Neutron Scattering and ¹³C magnetic relaxation study of the molecular dynamics in the nematic phase of EBBA. Attention has been focused on the relatively rigid biphenylic core of the molecule. In both cases a global model dependent fit of the obtained data has been performed. We were able to separate the rotational and translational contributions to QENS. The translational broadening displays an anomalous behavior in the high Q region which has been discussed against different diffusional mechanisms. The values of the rotational diffusion around the long molecular axis has been extracted as a function of temperature and compared to those measured with ¹³C magnetic relaxation of the orthophenylic carbons. Finally, the flexibility of the considered molecular fragment has been taken into account in interpreting the ¹³C relaxation data.

Key Words:

• nematics
• molecular diffusion
• QUENS, NMR