Mass spectrum of laser ionized diethyl ether clusters studied with ab initio calculation
乙醚团簇的激光电离质谱及从头计算

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 CH_3CH_2OCH_2CH_3),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 dipole-dipole interaction between the partners.Comparing with the binding energy 221.93?meV of complex(CH_3CH_2OCH_2CH_3)-H_2O,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.