Abstract
The temperature dependence of the spin-lattice relaxation time T1 is investigated in the chiral smectic liquid crystal (S)-4-(1-methylhexyloxycarbonyl)phenyl 4′-octyloxybiphenyl-4-carboxylate (S-MH(6)POBC) by solid-state 13C-NMR spectroscopy. The T1 of an aromatic carbon belonging to the core part of the liquid-crystalline molecule decreases from 1 s to 0.2 s with decreasing temperature in smectic phases, where the frequency of the molecular rotation around its long axis is higher than the Larmor frequency of 100 MHz in the present study. Because the molecular rotation freezes during the phase transformation from the smectic phase to the crystalline phase, T1 rapidly increases from 0.2 s to 16 s.
Acknowledgment
This work was supported by a Grant-in-Aid for Scientific Research C (No. 20550167) from the Ministry of Education, Culture, Sports, Science and Technology (MEXT).