N-芳基吡啶盐染料的一阶超极化率性质

在纳秒激光器上通过超瑞利散射 (HRS) 技术测定了具有推拉结构的 N-芳基取代吡啶盐类化合物的一阶超极化率，研究了它们的二阶非线性光学性质。结果表明，当吡啶环中N原子上的取代基由烷基变成芳基时，化合物的荧光发射强度急剧降低，但是一阶超极化率却明显增加。该系列化合物中两个相连的六元环破坏了吡啶盐的共轭平面结构，降低了化合物的荧光量子效率；另一方面，吡啶环上的取代芳基相对于烷基而言，其共轭体系增大，推拉电子能力增强，分子内电荷转移程度增大，从而提高了吡啶盐化合物的一阶超极化率。

First hyperpolarizabilities of N-aryl pyridinium dyes

First hyperpolarizability(β) values of a series of N-aryl pyridinium dyes with "push-pull" structure were measured by hyper-rayleigh scattering(HRS) technique with an Nd:YAG nanosecond laser.The result showed that fluorescence of these compounds decreased intensively but β values increased when alkyl was replaced with aryl at pyridine N atom.The simulative geometrical structure indicated that aryl substitute directly linked to pyridine ring broke the planarity of the conjugated system which decreased the fluorescence quantum field greatly.The increase of β might be mainly attributed to the enhanced electron-withdrawing abilities of corresponding aryl substitute.