¹³C-NMR Spin Lattice Relaxation Time Observation on the Smectic A and Smectic C^* Phases of a Chiral Smectic Liquid Crystal, (S)-4-(1-methylhexyloxycarbonyl)phenyl 4'-octyloxybiphenyl-4-carboxylate

Abstract

A new driving system of an insulated probe is proposed and compared in Ar RF plasma with the conventional insulated probe system using an operational amplifier for probe current detection. In this system, the probe is driven by a low-outputimpedance driver through a transmission line as long as a half-wavelength of the fundamental component of the RF, and the probe current is detected at the midpoint of this transmission line as a voltage signal. It was shown that measurement almost equivalent to that using an operational amplifier is possible with the use of a transmission line. The advantage of this system is that the flexibility of geometric design of the probe system is greatly improved without the parasitic effect due to the increase of stray capacitance.

Recent NMR Studies of Thermotropic Liquid Crystals

“…However, it is not straightforward to carry out these in reality. To list a few recent 13 C relaxation works, these include 10B1M7 [217], 4-(1-methylheptyloxycarbonyl)phenyl-4 0 -octyloxybiphenyl-4-carboxylate (MHPOBC) [218][219][220], 4-(2-methyloctanoyl)phenyl 4 0 -nonylbiphenyl-4-carboxylate (MONBIC) [216], 4-(1-methylhexyloxycarbonyl) phenyl 4 0 -octyloxybiphenyl-4-carboxylate (MH(6)POBC) [221]. In general, the 13 C T À1 1 rates of the aromatic carbons increase with decreasing temperature in a manner similar to the observed spectral densities for the aromatic deuterated sites (see for instant, ZLL 7/* [189]).…”

Phase transitions in ferroelectric liquid crystals

“…On the contrary, the rotational motion is hindered in the low temperature Sm C* phase so that the spontaneous polarization appears [26][27][28][29]. However, recently from a study of the rotational motion in DOBAMBC in the Sm A and Sm C* phases by 13 C-NMR Yoshimitsu et al [30] found that the activation energy in the Sm C* phase is rather small in comparison with that in the Sm A phase, which indicates that the rotational motion becomes less hindered in the Sm C* phase.…”

Molecular Dynamics in Smectic and Crystalline Phases Studied by13C-NMR Spin Lattice Relaxation Time Observation

“…As for its dynamical aspect, however, details of the hindered molecular rotation associated with the emergence of spontaneous polarization are still open for question, although several experimental approaches have been carried so far [1][2][3][4][5][6][7][8][9][10][11][12][13]. Although nuclear magnetic resonance (NMR) spectroscopy is a powerful method for investigating molecular dynamics in liquid-crystalline compounds, neither the slowing down nor the hindrance of molecular rotation has been confirmed even in recent studies [14][15][16][17][18][19][20][21][22][23][24][25].…”