中文摘要：

根据分子轨道理论，借助半经验分子轨道计算方法研究吡虫啉可能的的光解途径，发现硝基亚氨基是接受光子能量后最不稳定的位置，并预测了各种可能的光解产物．以300W中压汞灯（λ〉280nm）为光源，实验发现吡虫啉在甲醇溶剂中的光解符合一级动力学规律，其主要降解产物为1-[（6-氯-3-吡啶）甲基]-2-咪唑酮．实验结果与理论预测结果吻合，从而提出了吡虫啉可能的光解途径．

英文摘要：

In this paper, we predicted the photolysis pathways of imidacloprid by semiempirical molecular orbital theoretical computations. Firstly, we obtained the main transition styles of imidacloprid at λ〉 280 nm by Configuration Interaction. Then we calculated the value of △M/in these transition styles. The results showed that the bonds of N14-N15,C13=N14 and C8-N9 of imidaeloprid tended to break. On the other hand, photodegradation behaviors of imidacloprid in methanol were studied under irradiation of a 300 W medium pressure mercury lamp （λ〉280 nm）. The primary degradation of imidacloprid followed a pseudo-first-order kinetics in methanol, and the photodegradation half life of imidacloprid in methol is about 67, 9 min. The main photoproduct of imidacloprid was determined as 1-[ （6-chloro-3-pyridinyl） methyl]-2-imidazolidone by GC/MS, The results of theoretical prediction agreed well with the experimental conclusions, which suggested that semiempirical molecular orbital theoretical computations could be potentially applied to predict the photolysis pathways of organic contaminations.