组装L-B膜光学二次谐波的实验研究

一种分子形成的多层L-B膜由于相邻层的分子取向相反而使非线性极化抵消,总的X~(2)=0.本文用光学二次谐波方法确定了带有不同极性基团的L-B单分子层的有效非线性系数的大小和符号,对有效非线性系数符号相反的两种单分子层交替组装,使相邻单分子层的非线性极化相互叠加,得到了具有较大二阶非线性系数的组装L-B膜.

Experimental study on optical second harmonic generation of Langmuir-Blodgett monolayer assembly

The second order non-linear polarizability of Langmuir-Blodgett multilayer formed with one sort of molecules is zero because of the counteraction of non-linear polarization in adjacent monolayers which have opposite orientation. The magnitude and sign of effective non-linear optical coefficient of Langmulr-Blodgett monolayer with different polar groups have been studied experimentally by optical second harmonic gener ation technique. We alternatively assembled the monolayers which have opposite sign of polarizability and successfully have their non-linear polarizability superposed constructively. In this way, we can obtain a molecular membrance possessing much larger effective second order non-linear optical coefficient.