Deuteron magnetic resonance in liquid crystals : the interplay of molecular ordering and conformational changes

Abstract

Examination of deuteron magnetic resonance data in different thermotropic systems calls into question the explanation recently proposed by Bos and Doane wherein (i) the average molecular conformation does not change with temperature, even at phase transitions, and (ii) uniaxial and biaxial (Smc) mesophases are characterized by two and three molecular order parameters, respectively. Some counter-examples indicate that these points are not general, and in some cases ambiguities are present in their analysis. The role of conformational changes cannot be neglected