EVALUATION OF STRUCTURE AND OPTICAL PROPERTIES OF LB ULTRATHIN FILMS USING THE ATTENUATED TOTAL REFLECTION MEASUREMENT

本文用衰减全反射(ATR)法研究了LB超薄膜的结构和光学性质。我们已经研究了各种LB膜的ATR性质，用ATR方法研究了吸附给电子体和不吸附电子给体的四氰基喹甲烷LB膜的结构。通过对实验ATR曲线的拟合，确定了单轴各向异性介质方(SQ)LB膜的复介电常数。研究了螺吡喃(SP)与花生四烯酸、十八烷不同摩尔比的LB膜的ATR特性。含有十八烷的SPLB膜具有较高的有序性，并且由于光异构化而表现出可逆的变化。吸附菁染料的偶氮苯LB膜的ATR特性依赖于热处理后的激光波长，且复介电常数的实部随着波长的变短而减小。这些特性被认为是由于强吸收引起的反常色散所致。在具有聚酰亚胺LB取向层的液晶盒的ATR测量中，观察到表面等离子体波模式和导波模式的共振激发。根据测量结果估算了液晶盒中液晶分子5CB的倾斜角。利用ATR方法中的激发表面等离子体对花生状镉盐LB膜的表面粗糙度进行了估算。这些结果对LB膜的光学应用具有重要的指导意义。

In this report, structure and optical properties of LB ultrathin films have been evaluated using the attenuated total reflection (ATR) measurement. We have already investigated the ATR properties of various LB films.The structure of the tetracyanoquinodimethane LB films with and without adsorbed electronic donors was investigated using the ATR method. The complex dielectric constants of the squarylium (SQ) LB film of uniaxial anisotrpic dielectrics were determined by fitting the throretical ATR curves to the experimental ones. The ATR prorerties of the spiropyran (SP) LB films were obse ved for various molar ratios of the mixtures of SP,arachidic acid and octadecane. The SP LB films containing the octadecane had the higher order structure and exhibited the reversible changes due to the photoisomerization. the ATR properties of the azobenzene LB films adsorbing cyanine dyes depended upon the wavelength of the lasers after heat treatments, and the real parts of the complex dielectric constants decreased as the wavelength become shorter. The properties were thought to be due to an anomalous dispersion caused by strong absorption. The resonant excitaions of the surface plasmon wave mode and the guided wave ones were observed in the ATR measurements for the liquid crystal cell with the polyimide LB aligning layrs. Tilt angles of the liquid crystal molecules, 5CB,in the cell have been evaluated from the messurements. The surface roughness of the arachidic cadmium salt LB film was estimated using the excited surface plasmon in the ATR method. These results are very useful for optical applications of the LB films.