乙醚团簇的激光电离质谱及从头计算  

Mass spectrum of laser ionized diethyl ether clusters studied with ab initio calculation

作　　者：王艳[1] 张树东[1] 朱湘君[1] 孔祥和[1] 

机构地区：[1]曲阜师范大学物理工程学院,曲阜273165

出　　处：《物理学报》2007年第8期4491-4496,共6页Acta Physica Sinica

基　　金：曲阜师范大学博士科研启动基金资助的课题.~~

摘　　要：应用激光多光子电离质谱与超声脉冲分子束技术研究了乙醚团簇,实验中观测到乙醚的碎片离子以及强度较小的(E)H+,(E)2+和(E)2H+(E代表CH3CH2OCH2CH3),没有发现更大尺寸的团簇离子.结合从头计算理论,在B3LYP/6-311++G(d,p)基组水平上对乙醚团簇的可能构型进行优化及能量计算,发现乙醚二聚体的最稳定构型是一个乙醚分子中的氧原子和乙基分别与另一个乙醚分子的乙基和氧原子构成环状结构,考虑基组重叠误差修正的结合能为9.35meV,与其分子间的偶极-偶极相互作用能相当,远小于通过氢键结合的乙醚-水复合物的结合能221.93meV.由此推测乙醚通过偶极-偶极弱相互作用形成团簇,且以二聚体为核生长.由于结合能随团簇尺寸的增大而减小,因而实验中不易观测到更大尺寸的团簇.Diethyl ether clusters were studied using both laser multiphoton ionization mass spectrum and supersonic pulsed molecular beam technique. Only less intensity ions of （E）H^＋, （E）^＋2 and （E）2 H^＋ （E stands for CH3 CH20CH2 CH3 ）, accompanying with some stronger fragmented ions of diethyl ether, were observed. Using ab initio calculation to optimize the geometric structure and calculate the energy of diethyl ether clusters at B3LYP/6-311 ＋ ＋ G（d, p） level, the results show that the most stable structure of （ E）2 is a six-side-like ring, in which the oxygen atom and the ethyl group of one molecule are located close to the ethyl group and the oxygen atom of another molecule, respectively. The binding energy of （E）2 is 9.35 meV when considering the basis set superposition error with counterpoise method, which is equivalent to the dipele-dipele interaction between the partners. Comparing with the binding energy 221.93 meV of complex （CH3CH2OCH2CH3 ）-H20, which is associated by hydrogen bonding, it is suggested that the diethyl ether clusters are formed by weak dipole-dipole interaction and the initially formed dimmer acts as a seed for further cluster growth, meanwhile, as the binding energy decreases with size increasing, so larger clusters are not easily observed in experiment.

关 键 词：乙醚团簇 偶极-偶极相互作用 从头计算 

分 类 号：O561.2[理学—原子与分子物理]