【作者】 郭晶；

【导师】 闫冰；

【作者基本信息】 吉林大学 ， 原子与分子物理， 2012， 硕士

【摘要】 分子光谱是研究分子与辐射相互作用的学科，通过对各种光谱的研究能够了解分子的能级结构、电子态跃迁等方面的信息，近而得到关于分子结构与性质的知识。分子光谱是研究分子结构最重要的手段之一。可以说，今天所获得的有关分子结构方面的知识，大部分来自于分子光谱学的研究成果。光谱学是一门用途广泛的技术，在化学成份分析与物质结构的测定方面为我们提供了大量可靠的数据。现阶段关于Cl₂分子结构与光谱的报告和文献已经很多，但是与之相比较，Cl₂⁺分子离子的研究相对较少。Cl₂⁺分子离子在自然界中占有很重要的地位，Cl₂⁺分子离子是许多含氯分子电离、解离等化学、物理过程的中间产物，也是Cl2分子的电离产物。研究Cl₂⁺的电子结构与能级的信息有助于理解Cl₂分子与Cl₂⁺分子离子的物理和化学性质。我们使用量子化学程序包MOLPRO2010对Cl₂⁺分子离子进行了以下几个方面的理论研究：1.采用完全活性空间自洽场（CASSCF）和多参考组态相互作用（MRCI）方法计算了Cl₂⁺分子离子基态X2Πg的势能曲线。使用不同基组cc-PVXZ（X=T,Q,5,6）进行计算，并将计算结果外推到完全基（CBS）下。同时，我们分别考虑了标量相对论，自旋－轨道劈裂和芯－价壳层电子相关能（CV）等修正效应；结果表明，CV修正对势能曲线的影响较大。修正后的势能曲线与实验结果符合更好。2.基于上述计算所得到的Cl₂⁺分子离子基态X2Πg的势能曲线，我们计算了Cl₂⁺基态X2Πg的振动-转动能级，并与已有实验值进行了比较。结果表明计算得到的较低的振动能级与实验上的结果符合的非常好，同时，计算结果补充了实验上缺失的振动-转动能级信息。3.在本文中，我们讨论了同位素效应（35^Cl和37^Cl）对振-转常数的影响。由我们计算的结果可知，Cl₂⁺分子离子的同位素效应不明显，而且随着质量的增加，振-转能级有下降的趋势。此外，我们采用耦合簇理论，进一步计算了Cl₂⁺分子离子X2Πg态的解离能。4.在MRCI/aug-cc-pV5Z理论水平上，计算了Cl₂⁺分子离子与前三个解离限相对应的激发态势能曲线，并与实验上观测到的激发态相比较；同时表征了一些实验上没有观测到的激发态的势能曲线，并且计算了Cl₂⁺分子离子束缚态的光谱常数。更多还原

【Abstract】 Molecular spectroscopy is the disciplines to study the interaction betweenmolecules and radiation, which is helpful in understanding the electronic structuresand the transitions properties in molecules. Most of the information aboutmolecules is based on molecular spectroscopy. Molecular spectroscopy is one ofthe most important means in studying molecular structure. Nowadays，it can beconcluded that most knowledge on the molecular structure comes from molecularspectroscopy. Spectroscopy is a widely used technology, which provides us with alot of reliable data in determining the chemical composition and the structure ofmatter.Reports and documents of Cl2molecular structure and spectra at this stage isubiquitous, in contrast, reports of Cl₂⁺molecular ion are very rare. Cl₂⁺molecularion plays an important role in nature world; it is not only the intermediates of thechemical, physical processes of many molecules with chlorine, but also theionization product of Cl2molecules. The study of Cl₂⁺electronic structure andenergy levels will be useful to understand the physical and chemical properties ofthe Cl2molecules and Cl₂⁺molecular ions.We use the quantum chemistry package MOLPRO2010calculate someaspects of Cl₂⁺molecular ion theoretically: 1. The complete active space self-consistent field （the CASSCF） andmulti-reference configuration interaction （MRCI） methods were used tocalculate the potential energy curve of the ground state X2Π+gof Cl2molecularion. Firstly we employ different basis sets cc-PVXZ （X=T, Q,5,6） in ab initiocalculations, the calculated results were extrapolated to complete basis set（CBS）. At the same time, we also take the scalar relativistic, spin-orbit coupling,and core-valence （CV） shell electron correlation energy corrections intoaccount. The results show that the CV correction has a greater impact on thepotential energy curve, and the modified potential energy curve match with theexperimental results better.2. According to the calculation result of ground state X2Πgof Cl₂⁺molecular ion,we calculate the vibration-rotational levels of ground state X2Πgof Cl₂⁺molecular ion, and they are comparable with available experimental values.The results show that the calculation error falls into the experimental error bar,and the lower vibrational levels of calculated results in line with theexperimental ones, at the same time, the calculation results complement thelack of vibration-rotational energy levels on the experiment.3. In this article, we discuss the isotope effect （35Cl and37Cl） on vibrational-rotational constants. The results show that the isotope effect of Cl₂⁺molecularion is not palpable; there was a downward trend of vibrational-rotationalenergy with increasing of mass. In addition, we adopt the coupled-clustertheory to calculate dissociation energy of X2Π+gstate of Cl2molecular ion. 4. At MRCI/aug-cc-pV5Z theoretical level, we calculated potential energy curvesof excited states of Cl₂⁺molecular ion that correspond to the first threedissociation limits. And we also compare these excited state with the oneswhich already been observed. As the same time, we give some excited stateswhich have not been observed. We also calculate spectroscopy constants ofbound states of Cl₂⁺molecular ion.更多还原