Deuteron relaxation in liquid crystals: Di-n-alkoxyazoxybenzenes, n=1,7

Abstract

Deuteron spin lattice relaxation T_1Q has been measured in the liquid crystal and liquid phases of di‐methoxyazoxybenzene deuterated at the aromatic positions (PAA‐d8) and di‐n‐heptyloxyazoxybenzene similarly deuterated (HOAB‐d8). T_1Q of PAA‐d8 was measured at 4.5 and 10.5 MHz over the entire liquid crystal range and also at 15.35 MHz at 133 °C, just below the clearing point. No frequency dependence was observed. In contrast to proton relaxation, T_1Q is strongly temperature dependent in the mesophases of both compounds. The results indicate that relaxation in this frequency range is more strongly influenced by rapid molecular reorientation and internal rotations than by collective mode mechanisms.