乙醚团簇的激光电离质谱及从头计算

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 关键词： 乙醚团簇 偶极-偶极相互作用 从头计算

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

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)₂H⁺(E stands for CH₃CH₂OCH₂CH₃), 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 9.35meV when considering the basis set superposition error with counterpoise method, which is equivalent to the dipole-dipole interaction between the partners. Comparing with the binding energy 221.93meV of complex (CH₃CH₂OCH₂CH₃)-H₂O, 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.