摘 要
论文采用共振多光子电离和Ion-dip两种检测手段对碱土金属单卤化物的里德堡态进行了实验研究。主要成果是：⑴首次观测到中等有效主量子数的CaCl预解离里德堡态：在n*=5-7区域内，有5个文献未报导过的2+实贯穿里德堡态，填补了CaCl分子此一区域里德堡态研究的空白，对CaCl里德堡态结构的完整分析和其电子态完整的图像的建立具有重要意义；⑵通过理论分析，论证了这些态是因为和一个2+连续态的相互作用而导致强烈的预解离。由实验测定的预解离线宽拟合出45000-47500cm-1范围内的2+连续态势能曲线，它能很好地解释这些里德堡态的预解离行为；⑶还观测到若干转动常数值反常小的里德堡态，它们可能是实非贯穿里德堡态的片段。以上结果为阐明高极化分子的离解机理和其他的动力学过程提供了丰富的信息。
论文第二部分工作是采用微扰增强的光学－光学双共振荧光探测方法研究Na2分子的高激发三重电子态。主要结果为：⑴首次观测到Na2的13g-双电子激发价态，并归属了该电子态的v=0~57振动能级，它们覆盖了整个势阱的99%以上。并发现13g-态能级即使超过电离限时亦无明显的自电离倾向，反映了双电子激发态不同于里德堡态的独特性质。13g-态是碱金属双原子分子电离限以下唯一的3g-对称性的态和电离限下唯一较纯的双电子激发态，这些结果为分子结构和量子化学的定量研究提供了重要的信息；⑵通过检测Na 3d3p原子荧光，观察到Na2分子的33g和43g+态在3s+3d解离限以上的预解离能级及其转动线宽加宽；⑶利用从头计算势能曲线对33g和43g+态预解离机理作了深入的理论分析与论证。结果表明：33g态在3s+3d解离限以上能级强烈的预解离是由于23g和33g之间的静电相互作用，其寿命缩短到102飞秒量级。43g+态的预解离则主要是通过和23g连续态的直接相互作用以及通过预解离的33g能级与23g态的间接相互作用（偶然预解离）；⑷新观察到Na2的(3s+nd) (n=5~7) 4, 7, 103g三重里德堡态并首次在Na2分子中得到三重里德堡系列的量子亏损。以上一系列Na2高激发态新光谱线的发现及其合理的量子力学解释，在前人基础上进一步丰富了关于双原子分子双电子激发态和里德堡态的知识。
关键词：分子电子激发态，里德堡态，预解离，Na2，CaCl
Abstract
Electronic excited state is one of the common forms in which atoms, molecules and ions exist in the nature. Study on the characters and dynamics behaviors of the molecular excited states, such as energy levels, lifetimes, predissociation and auto-ionization, as well as on their electronic structures, is not only a significant topic related to chemical reactions and chemical dynamics, but also one of the frontiers in the field of atomic and molecular physics.
In present dissertation, experimental studies of the predissociated Rydberg states of CaCl by using the resonance enhanced multiphoton ionization (REMPI) and ion-dip detection spectroscopy were carried out. Five core-penetrating Rydberg states of CaCl in the intermediate effective principle quantum number region, n*=5~7, were observed for the first time. Theoretical analysis confirmed the predissociation mechanism which supposed these Rydberg states were led by an interaction with a 2+ continuum state. A potential energy curve of this 2+ continuum state in the energy region of 45000~47500cm-1 was fitted based on the observed predissociation linewidths. Some Rydberg levels with anomalously small rotational constants were also observed. They might be the fragments of the core-nonpenetrating Rydberg states. All these results provide rich information for understanding the mechanism of dissociation of molecules with highly polar core and some correlative dynamical processes. 英语毕业论文----德维在线 www.devay.net
Systematical investigation on the high-lying triplet gerade states of Na2 by using the perturbation facilitated optical-optical double resonance (PFOODR) method is also made. A doubly excited valence state of Na2, 13g- state, which consists in the unique 3g- state as well as the unique pure two-electron excitation state below the ionization threshold, was first observed and characterized. A number of v=0~57 vibration levels were determined and assigned. The levels cover more than 99% of the potential well depth of the state. No evident autoionization was found related to the levels belonging to the 13g- state above the ionization threshold, implying the distinct character of the doubly excited valence state from the Rydberg states. The observation of this state is of great importance for expounding homo-diatomic molecular structure in quantum chemistry.
The energy levels of 33g and 43g+ states of Na2 above the 3s+3d atomic limit were detected by monitoring of the 3d3p fluorescence of Na atom. An obvious rotational line broadening was observed. A theoretical analysis of the predissociation mechanism of the 33g and 43g+ states based on the ab initio potential energy curves was presented. The strong predissociation of the 33g levels above the 3s+3d limit is due to the electrostatic interaction with the 23g state, resulting in their lifetime as short as hundreds of femtoseconds. The predissociation mechanism of the 43g+ state was determined also. Both the direct predissociation by the 23g state and the accidental predissociation by the 23g state via the 33g state could have contributed to the predissociation of the 43g+ state. The theoretical predictions were in fairly good agreement with the experimental observations.
The (3s+nd) (n=5~7) 4, 7, and 103g Rydberg states of Na2 were observed and the quantum defect of its triplet Rydberg series were first obtained.

Key words: molecular excited state, rydberg state, predissociation, Na2, CaCl