铁电液晶MBOPDOB相变的光散射研究

我们对铁电液晶 MBOPDOB 进行了温度有关的拉曼散射研究。在低频范围记录了三条拉曼谱线(15,49,93cm~(-1))。其中15和49cm~(-1)谱线消失于 C-Sm C相变温度,没有检测到任何频移现象。93cm~(-1)拉曼线产生部分频移,消失于各向同性相,联系着偶极-偶极互作用。高频范围四个振动模(1178和1116cm~(-1),1710和1738cm~(-1))之间能量转移归于由电子转移引起的 C=0键硬化和 C-0健的弱化。同时也讨论了该液晶 Sm C-Sm A 相变的二级连续型特征。

Light scattering study on phase transitions in ferroelectric liquid crystal MBOPDOB

Temperature-dependent Raman spectra of ferroelectric liquid crystal MBOPDOB were examined.Three Raman lines at 15,49 and 93cm~(-1) were recorded in lower spectral region,and two lines at 15 and 49cm~(-1) Vanish at C-Sm C transition temperature without any detectable freqency shift.The line at 93 cm~(-1) partly shifts and dissappears at isotropic phase which are concerned with dipole-dipole interaction.There are four Vibrational modes at 1178,1166,1710 and 1738 cm~(-1) in the higher spectral region.The energy transfer between the former two modes and between the latter two modes is attributed to the stiffening of the C=O bond and the weakening of the C-O bond by the electron transfer.The properties of Sm C-Sm A transition of Second-order continuous type in the liquid crystal are also discussed.