2-硝基萘激发态衰减动力学和光解通道的从头计算研究  

Study on the Decay Dynamic of Excited State and Photodissociation Channel for 2-Nitronaphthalene

作　　者：杨梦 张腾烁 郑旭明[1] 薛佳丹[1] YANG Meng;ZHANG Tengshuo;ZHENG Xuming;XUE Jiadan(Department of Chemistry,School of Science,Zhefiang Sci-Tech University,Hangzhou 31 O018,China)

机构地区：[1]浙江理工大学理学院化学系,杭州310018

出　　处：《高等学校化学学报》2018年第8期1734-1740,共7页Chemical Journal of Chinese Universities

基　　金：国家"九七三"计划项目(批准号:2013CB834604);国家自然科学基金(批准号:21202032;21473163);浙江省自然科学基金(批准号:LY16B030008)资助~~

摘　　要：采用密度泛函理论(DFT)和完全活化空间自洽场理论(CASSCF)计算方法,在CASSCF(10,10)/6-31G(d)//CASPT2(10,10)/Aug-cc-PVDZ计算水平下,研究了2-硝基萘(2NN)S1(ππ*)激发态的衰减动力学.获得了2NN及其亚硝酸酯异构体(ISO)的基态、低能激发态和势能面交叉点的优化结构和能量,以及异构化反应的过渡态结构和能垒;给出了S0,T1和S1态时ISO沿N—O键的势能曲线;描绘了激发态衰变路径图.结果表明,被激发至S1(ππ*)激发态后,2NN经S1T3,S1T2交叉点发生S1!T3,S1!T2系间窜越过程再经T2T1锥形交叉点发生T2!T1内转换过程,最后无辐射衰减到T1态.具体衰减路径可以描述为S1-FC-2NN!S1T3-MIN-2NN或S1T2-MIN-2NN!T3-MIN-2NN或T2-MIN-2NN!T2T1-MIN-2NN!T1-MIN-2NN.该条路径能垒较小,T1态瞬态物种形成效率较高,为2NN激发态衰变动力学中最重要的无辐射衰变通道.在S0,T1和S1态势能面上,2NN!ISO异构化反应的能垒高,跃迁概率十分低下,难以形成芳氧自由基(Ar O"),2NN紫外光解离效率很低.Density functional theory（ DFT） and complete active space self-consistent field（ CASSCF） calculation methods,combination with the level of activation space（ 10,10）,and basis set 6-31 G（ d） were used to obtain structures information of ground state,excited states,intersections and transition states for 2-nitronaphthalene（ 2 NN） and its nitrous acid ester isomer（ ISO）. Multi-configurational second-order perturbation（ CASPT2） method with basis set Aug-cc-PVDZ was adopted in calculating the energy of all the given structures and the Frank-Condon areas. At the same time,the potential energy surface scans along N—O bond were carried out to determine the feasibility of the dissociation for isomers. Finally,the overall picture of decay dynamics for 2 NN after being excited to S1-FC（ ππ＊） was presented based on those calculation results. The results show that the nonradiative decay pathway to T1 state of 2 NN originates from S1-FC（ ππ＊）,undergoes intersystem crossing and internal conversion through curve-crossing points of S1 T3,S1 T2 and T2 T1. Thus the efficient decay channel can be： S1-FC-2 NN!S1 T3-MIN-2 NNor S1 T2-MIN-2 NN!T3-MIN-2 NNor T2-MIN-2 NN!T2 T1-MIN-2 NN!T1-MIN-2 NN. This pathway is the most important nonradiative decay channel for excited state decay dynamics of2 NN due to the small energy barrier and high efficiency of forming transient species of T1 state. In addition,calculation results on the potential energy surface suggest that isomerization reactions from 2 NN to ISO need to overcome big energy barriers in S0,T1 and S1 states,respectively,which results in the pretty low efficiency of Ar O＂radicals.

关 键 词：2-硝基萘 完全活化空间自洽谈场理论 衰减动力学 异构化反应 光解离 

分 类 号：O641[理学—物理化学]