Ferroeloctricity in cholesteric liquid crystals of polypeptide and its helicoidal cavity effect of SHG

多肽胆甾液晶的铁电性及其二次谐波螺旋腔效应

• 批准号: 10450361
• 负责人: WATANABE Junji
• 金额: $ 8.13万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10450361/
• 关键词: polypeptide; cholesteric liquid crystal; helical structure; second harmonic generation; ferroelectricity; helicoidal cavity effect; dipole moment; polar structure; らせん分布型キャビティー効果; 強誘電液晶

Relatively strong second harmonic generation (SHG) was observed in the lyotropic cholesteric phase of the poly(γ-benzyl L-glutamate) (PBLG) in benzyl alcohol (BA) with application of an electric field. Using an SHG interferometry technique, we confirmed that the phase of SHG was reversed by reversing the electric field, clearly indicating the switching of nonlinear polarization. By applying a triangular wave voltage, a switching current peak was observed, indicating the existence of spontaneous polarization.SHG was also observed in a cholesteric solid film of PBLG using fundamental light propagating along the helicoidal axis. Relatively strong SH light was observed when the optical pitch in the helicoid was the same as the SH-light wavelength, although, otherwise, the generated SH light was canceled by the helicoid so that the SH intensity was negligibly weak.Based on these experimental results, we safely concluded that the cholesteric phase of the PBLGBA lyotropic system is in fact a ferroelectric cholesteric phase, where a polar plane rotates along the helical axis. This is the first proper ferroelectricity in liquid crystals.

我们利用SHG干涉技术，在苯甲醇（BA）中的聚（γ-L-谷氨酸苄酯）（PBLG）的溶致胆甾相中观察到相对较强的二次谐波产生（SHG）。通过反转电场，SHG 的相位发生反转，清楚地表明非线性极化的切换。通过施加三角波电压，观察到切换电流峰值，表明存在。使用沿着螺旋轴传播的基本光，在 PBLG 的胆甾型固体膜中也观察到了 SHG，当螺旋中的光学螺距与 SH 光波长相同时，观察到相对较强的 SH 光。 ，产生的 SH 光被螺旋抵消，因此 SH 强度可以忽略不计。基于这些实验结果，我们有把握地得出结论，PBLGBA 溶致性的胆甾相该系统实际上是铁电胆甾相，其中极面沿螺旋轴旋转，这是液晶中第一个适当的铁电性。

项目成果

H. Hakezoe and J. Watanabe: "Ferroelectricity in Liquid Crystals"Mol. Cryst. Liq. Cryst.. 328. 325-372 (1999)

H. Hakezoe 和 J. Watanabe：“液晶中的铁电性”Mol。

J. Watanabe, et. al.: "Polar structure in polypeptide cholesteric liquid crystals evidenced from SHG due to the helicoidal cavity effect"Macromolecules. 31, (19). 5937-5939 (1998)

J.渡边等。

J.Watanabe 他4名: "Enhancement of second harmonic generation due to the selective reflection of cholesteric liquid crystals"Mol.Cryst.Liq.Cryst.. (in press).

J. Watanabe 和其他 4 人：“由于胆甾型液晶的选择性反射而增强二次谐波的产生”Mol.Cryst.Liq.Cryst..（出版中）。

J. Watanabe, et. al.: "Ferroelectricity of lyotropic liquid crystal of poly L-glutamate"Jpn. J. Appl. Phys.. 37. L136-L138 (1998)

J.渡边等。

J.Watanabe 他2名: "Molecular Modeling of Polar Rod Like Molecules"Mol.Cryst.Liq.Cryst.. (in press).

J. Watanabe 和另外 2 人：“极棒状分子的分子建模”Mol.Cryst.Liq.Cryst..（正在出版）。