Temporary Anions and Dissociative Attachment: Probes of Intra- and Intermolecular Interactions

在化学部实验物理化学计划的这个项目中，Burrow（内布拉斯加大学）和Jordan（匹兹堡大学）将继续联合实验和理论研究气相取代烃中临时阴离子的形成。 在这两个机构的实验研究将检查振动激发和解离附着（DA）反应，其中产生稳定的碎片阴离子。 将测量用于形成临时阴离子的总DA横截面和垂直附着能（VAE）。 一个新的仪器将被构建来测量由DA产生的碎片阴离子的角度依赖性。溶剂化对临时阴离子的能量和衰变性质的影响将被检查在氯甲烷（CH3Cl）与溶剂，如水共膨胀。 高层次的电子结构计算将进行预测的垂直连接能量是如何受到溶剂化。 占据和未占据电子态的概念提供了可视化分子结构和化学反应性的有力手段，这些电子态也被称为轨道。 光电子能谱长期以来提供了一种研究占据轨道的方法，但直到最近，正常未占据轨道的相应数据一直很稀少。 这项工作旨在收集这些数据，从而帮助回答复杂分子中结构和键合的关键化学问题。 它还提供了电子转移模型的关键数据，电子转移是涉及各种化学过程的机制，如光合作用，光诱导表面解吸，化学致癌作用和生物修复。

In this project in the Experimental Physical Chemistry Program of the Chemistry Division, Burrow (University of Nebraska) and Jordan (University of Pittsburgh) will continue joint experimental and theoretical studies of temporary anion formation in gas-phase substituted hydrocarbons. Experimental studies at both institutions will examine vibrational excitation and dissociative attachment (DA) reactions in which stable fragment anions are produced. Both total DA cross sections and vertical attachment energies (VAEs) for formation of temporary anions will be measured. A new instrument will be constructed to measure the angular dependence of fragment anions produced by DA. The effect of solvation on the energies and decay properties of temporary anions will be examined in methyl chloride (CH3Cl) co-expanded with solvents such as water. High-level electronic structure calculations will be carried out to predict how the vertical attachment energy is influenced by the solvation. A powerful means of visualizing molecular structure and chemical reactivity is provided by the concept of occupied and unoccupied electronic states, which are also known as orbitals. Photoelectron spectroscopy has long provided a means of studying occupied orbitals, but until recently the corresponding data for normally unoccupied orbitals has been scarce. This work aims at gathering such data, thereby helping to answer key chemical questions on structure and bonding in complex molecules. It also offers data crucial to models of electron transfer, which is the mechanism involved in a large variety of chemical processes, such as photosynthesis, light-induced desorption from surfaces, chemical carcinogenesis, and bioremediation.