CF_3 Cl,CF_2 Cl_2和CFCl_3分子外价壳层轨道特性的电子动量谱学研究

An electron momentum spectroscopic research of the character of outer valence orbitals for CF_3Cl, CF_2Cl_2 and CFCl_3

通过比较相同电子成分轨道的实验和DFT-B3LYP/6-311+G*理论的电子动量分布,系统研究了CF_3Cl,CF_2Cl_2和CFCl_3分子外价壳层的轨道特性.研究结果表明CF_3Cl,CF_2Cl_2和CFCl_3分子的Cl(3p)孤对电子轨道随着Cl原子个数增多,分子内相互作用逐渐增强,Cl原子3p轨道电子动量分布的特征逐渐淹没;F孤对电子轨道和的电子动量分布在高动量区出现了一个弱结构,且随Cl原子个数增多和F原子个数减少逐渐消失,这可能是由于部分轨道C_Clσ键电子成分的贡献;除3a_1 轨道外,C-F成键轨道和的理论的电子动量分布均在低动量端低于实验结果,可能是由于"d-like"轨道低动量端的扭曲波效应;3a_1轨道理论的电子动量分布均在0.3a.u.<p<0.8a.u.范围内低于实验结果,可能是由于扭曲波效应和电子关联等效应的影响.

The character of outer valence orbitals for series molecules CF_3Cl,CF_2Cl_2 and CFCl_3 are researched by comparing the experimental and DFT-B3LYP/6-311+ G * theoretical electron momentum distribution for same element orbitals of three molecules. It is show that for Cl(3p) lone-pare orbitals, with the increase of number of Cl,Cl 3p character in electron momentum spectroscopy are gradually disappeared , and the interaction in molecule is increased. A weak structure appeared in electron momentum distribution of F lone-pare orbitals for three molecules. And it is gradually disappeared when the number of Cl are increased. A possible reason is the contribution of C-Cl σ bond for some of these orbitals. Except 3a_1 ,the theoretical electron momentum distributions of C-F bonding orbitals are lower than the experi- mantl ones for three molecules. The distorted-wave effect for 'd-like' orbital is considered as a proper reason. For 3a_1, all theoretical lines are lower than experimental ones in the region The distorted-wave effect and electron correlation effect should be considered.