制备条件对Langmuir－Blodgett膜中分子聚集态的影响

通过对不同制膜条件下样品的π－Ａ曲线及紫外－可见吸收光谱的测量，研究ＬＢ单分子层膜中半花菁衍生物（ｈｅｍｉｃｙａｎｉｎｅｄｅｒｉｖａｔｉｖｅ简称ＨＤ）分子的聚集状态及其形成机制。纯半花菁衍生物单分子层膜中分子以Ｈ聚集体的形式存在导致吸收峰的兰移及有效分子二阶非线性极化率β（基频波长λ＝１．０６４μｍ）的减小。实验表明聚集体的形成主要发生在压膜过程。提高压膜速度或降低压膜终极压力（拉膜压力）可显著减小分子的聚集程度，从而提高单分子层膜的光学非线性极化率。

Effects of Preparation Conditions on the Molecular Aggregations in Langmuir-Blodgett Films

We investigated the aggregation status and formation mechanisms of a hemicyanine derivative(HD)in Langmuir-Blodgett monolayers prepared under different conditions by π-A isotherm and UV-vis absorption measurements.The HD molecules formed H-aggregates in LB monolayers leading to a blue-shift of the absorption peak with respect to that of the monomeric HD in the chloroform solution and reduction of molecular hyperpolarizability β(the fundamental wavelength λ=1.064 μm)through a second-harmonic off-resonant effect. The H-aggregate formation mainly occurred and effective molecular hyperpolarizability β could be enhanced by raising the compressional speed and/or lowering the deposition surface pressure.