论文标题
分子双轴性决定了螺旋结构 - 在二氟苯基二聚体的NTB相中分子阶的红外测量
Molecular biaxiality determines the helical structure -- Infrared measurements of the molecular order in the NTB phase of difluoro terphenyl dimers
论文作者
论文摘要
采用了IR极化光谱法，以获得含有双氟二苯基核心的弯曲形二聚体（n = 5,7,9,11）的串联DTC5CN（n = 5,7,9,11）的三个成分。然后，用于计算各种分子二聚体基团的单轴（S）和双轴（D）阶参数。由于观察到的苯基核心和中央碳氢化合物接头的S参数之间的差异，因此估计了分子弯曲。尽管几乎没有宏观主管Bend，但发现它在N期很重要。顺序参数S的温度依赖性s明显地逆转了其单调趋势的增加趋势，以在过渡温度，TN-NTB降低到NTB相，因为董事倾斜在NTB阶段。双轴顺序参数D在N相中可以忽略不计，然后在进入NTB温度时开始增加，与SIN2Q相似。发现局部主曲率被分子双轴参数控制。
IR polarized spectroscopy was employed, to obtain the three components of IR absorbance for a series DTC5Cn (n=5,7,9,11) of bent-shaped dimers containing double fluorinated terphenyl core. Then, they were used to calculate both uniaxial (S) and biaxial (D) order parameters, for various molecular groups of dimers. The molecule bend was estimated due to observed difference between S parameters for the terphenyl core and central hydrocarbon linker. It is found to be significant in N phase despite almost no macroscopic director bend. The temperature dependence of the order parameter, S, distinctly reverses its monotonic trend of increase to decrease at the transition temperature, TN-NTB to the NTB phase as result of the director tilt in the NTB phase. The biaxial order parameter, D, is negligible in the N phase, and then starts increasing on entering the NTB temperature, similarly to sin2q. The local director curvature is found to be controlled by the molecular biaxiality parameter.
