摘要
本文采用引入外场微扰的CNDO/S-CI方法,计算了一系列取代共轭多烯分子的二阶非线性光学系数β_(vec),探讨了取代基及共轭链长与分子微观非线性光学效应的关系和规律.结果表明:吸电子或供电子基团的引入,有利于增强分子的微观非线性光学效应,但该效应随取代基数目增多有减缓的趋势,“饱和”取代时由于“饱和效应”而使β_(vec)值降低;取代基间的距离增大,分子的β_(vec)值提高,端基取代时β_(vec)值最大;取代共轭多烯的lnβ_(vec)与分子中所含双键数n之间具有线性关系.本文还对上述结论给出了理论解释.
The second order nonlinear-optical coefficients of a series of substituted polyenes have been calculated by the semi-empirical CNDO/S-CI method. The results show that the introduction of the electronic donor or acceptor and the increase in the distance between the substituents and the length of the conjugated chain may enhance NLO response. It is also shown that the calculated In β_(vec) is linear with the number of double bonds in planar and linear transpolyenes. A saturation effect in substitution is discovered. The theoretical explanations are presented for these results. Based on our discussion one can get the guidelines for synthesis of molecules with larger SHG coefficients.
出处
《化学学报》
SCIE
CAS
CSCD
北大核心
1992年第8期783-787,共5页
Acta Chimica Sinica
