CAUTERIZATION OF DIELECTRIC PROPERTIES FOR MONOLAYERATAIR-WATER INTERFACE BY MEANS OF MAXWELL DISPLACEMENT CURRENT AND OPTICAL SECOND HARMONIC GENERATION MEASURMENT

本研究的目的是通过麦克斯韦位移电流(MDC)和光学二次谐波(SHG)测量来表征有机单层膜的线性和非线性介电性质。宏观介电性质，如线性和非线性介电常数，与组成分子的取向有序参数密切相关。从这一角度出发，本研究基于研究者提出的MDC测量与倍频测量相结合的思想，测量了NCB和nOCB分子表面单分子膜的MDC和SHG信号，并利用532(和1064 nm)基波构建了一种新的测量系统，以获得高信噪比。利用实验结果，在量子化学三态模型的基础上，阐明了MDC与偶氮分子光异构化的关系，并用连续介质弹性理论分析了磷脂和液晶单分子膜的相变。他们在nOCB液晶单分子膜中检测到了这种相变。最后，导出了C_2对称性中微观和宏观非线性极化率之间的理论关系。

The purpose of this investigation was to characterize the linear and nonlinear dielectric properties of organic monolayer films by means of Maxwell-displacement current (MDC) and optical Second Harmonics Generation (SHG) measurement. The macroscopic dielectric properties such as linear and nonlinear dielectric constants are strongly related to the orientational order parameters of the constituent molecules. From this point of view, this investigation has been carried out on the basis of the idea of MDC measurement coupled with SHG measurement, proposed by the investigators.The investigators measured MDC and SHG signals from the monolayer on the water surface of nCB and nOCB molecules, where they constructed a new measurement system using 532 (and 1064 nm) fundamental waves to gain the high SN ratio. Using the experimental results, they clarified the relationship between MDC and photoisomerization of azo-molecules based on the quantum chemical three-state model Furthermore they analyzed the phase transition occurring in phospholipid and liquid crystal monolayers using a continuum elastic-theory. They detected this kind of phase transitions in nOCB liquid crystalline monolayer. Finally they derived the theoretical relationship between the microscopic and macroscopic nonlinear susceptibilities in C_2 symmetry.