大气中单个水分子影响HOBr+OH·反应的理论研究  

Theoretical Studies on the Single Water Molecule Effects on the Reaction of HOBr with OH·

作　　者：高成贵[1] 隆正文[1] 谭兴凤[2] 龙波[2] 龙超云[1] 秦水介[1] 张为俊[3] 

机构地区：[1]贵州大学物理系,贵阳550025 [2]贵州民族大学信息工程学院,贵阳550025 [3]中国科学院安徽光学精密机械研究所环境光学实验室,合肥230031

出　　处：《化学学报》2013年第5期849-856,共8页Acta Chimica Sinica

基　　金：国家自然科学基金(No.41165007);贵州省科学技术基金(Nos.黔科合J字[2011]2107;黔科合J字[2012]2189);中国科学院大气成分与光学重点实验室(No.JJ1107);贵州大学研究生创新基金(2013023)资助~~

摘　　要：在aug-cc-pVTZ基组下采用CCSD(T)和B3LYP的理论方法,研究了OH·与HOBr的反应,并考虑在大气中单个水分子对HOBr+OH·反应机理及动力学的影响.理论计算表明:对于OH+HOBr反应,发现了两个反应通道及其对应的反应前络合物,且计算出的能垒与实验结果符合得较好,当加入一个水分子后,共找到6个不同的反应通道.更加重要的是对于HOBr与H2O…HO·氢键络合物反应,反应能垒降低约1.00 kcal·mol-1.为了评估这些过程在大气化学中的重要性,应用过渡态理论计算各个反应通道的反应速率常数.计算结果表明,在298 K,没有水分子参加反应的反应速率常数为1.77×10-13cm3 molecule-1·s-1,与以前的理论计算一致.当加入水分子时,HOBr…H2O+OH·反应速率常数增加约50倍.In this article, the reactions of OH. with HOBr in the absence and presence of water are investigated using the CCSD（T） and B3LYP theoretical methods at the aug-cc-pVTZ basis set. The goal of the present investigation is to determine how the single water molecule can affect the reaction mechanisms and kinetics of OH.＋HOBr and estimate the importance of water effects on the OH. ＋HOBr reaction. The calculated results show that there are two reaction channels and the corre- sponding pre-complexes for the reaction of OH-＋ HOBr. The barriers of the reaction OH. ＋ HOBr are 1.13 kcal.mo1-1, 2.02 kcal.mol-~, respectively, which are in good agreement with the previous experimental and theoretical results. In addition, the reaction of OH. ＋HOBr is very complex when one water molecule is introduced because there are six reaction pathways and corresponding pre-reactive complexes. In particular, the activated barriers of the reaction HOBr＋ H20＂＂HO＂ are about 1.00 kcal.mo1-1 lower than those of the naked reaction OH. ＋HOBr. Additionally, to estimate the importance of these processes in the atmosphere, the rate constant is evaluated using the conventional transition state theory with Wigner tunneling correc- tion. The calculated rate constant of the naked reaction is 1.77 ~ 10-~3 cma.molecule-l.s-1 at 298 K, which is consistent with the previous computational value. However, the rate constant of HOBr＇-＇H20＋OH. reaction is 50 times faster than that of the naked reaction OH. ＋HOBr. Combined with concentrations of these species in the atmosphere, the reaction of OH. with HOBr in the presence of water is less important than the naked reaction OH.＋HOBr. However, water effects on the OH.＋ HOBr are very obvious, which is very similar to the reaction OHo＋HOC1. Therefore, the present study provides further in- sight into water effects in the atmospheric chemistry.

关 键 词：大气化学 HOBr 羟基自由基 水分子 反应机理 反应动力学 

分 类 号：O643.12[理学—物理化学]