二次谐波线二向色性方法研究气液界面手性的理论分析与实验  

Theoretical Analysis and Experiment of Monolayer Chirality at Air/Water Interface by in situ Surface Second Harmonic Generation Linear Dichroism

作　　者：王晓宇[1] 李林[1] 林路[2] 张贞[2] 陆洲[2] 郭源[2] 

机构地区：[1]北京理工大学光电学院,北京100081 [2]中国科学院化学研究所,北京100190

出　　处：《光学学报》2015年第3期225-233,共9页Acta Optica Sinica

基　　金：国家自然科学基金(91027042;21227802)

摘　　要：二次谐波线二向色性方法是定量研究气液界面手性的重要光学方法,此方法得到的手性响应既可能来源于界面超分子的电偶极矩的贡献,也可能是电偶极矩和磁偶极矩的共同贡献。分清这两种贡献,是研究界面超分子手性形成机理的前提条件。对两种情况下S偏振的二次谐波强度的偏振公式进行了对比分析和数值模拟,总结了各自的偏振曲线的线型特点,进一步分析了电偶极矩和磁偶极矩的二阶非线性极化率张量分量对手性响应的影响。推导了两种情况下表征界面手性的物理量——手性过量的表达式,分析了电偶极矩和磁偶极矩对手性过量的影响。通过卟啉气液界面手性的实验检测结果,验证了理论分析的正确性,该模拟对实验数据分析有重要意义。Second harmonic generation（SHG）- linear dichroism（SHG- LD） is an important method for the investigation of monolayer chirality at air/water interface. The chirality SHG response may originate from the contributions of electric dipole transitions or from contributions of both electric dipole transitions and magnetic dipole transitions. The distinction between these two cases is a prerequisite when studying the formation mechanism of the interfacial supramolecular chiraliy. The numerical simulations of the S-polarized SHG intensity as a function of the incident polarization angle are presented and compared for the two cases. The influences on the chirality SHG responses from the second-order nonlinear susceptibility tensors which account for the contributions of electric dipole transitions and magnetic dipole transitions are also analyzed, respectively. In addition, the significance of theoretical simulations to the analysis of experimental data is verified by the SHG- LD experiments on the supramolecular chirality of the porphyrin molecules at air/water interface.

关 键 词：非线性光学 手性 二次谐波的线二向色性 电偶极跃迁 磁偶极跃迁 

分 类 号：O436[机械工程—光学工程]