Rapid Reactions of Ions and Radicals in Organized and Constrained Media: Polymer Films and Zeolites

在有机动力学项目的支持下，圣母大学的克里·托马斯教授研究了离子和自由基在有组织和受限制的介质中的快速反应。分子筛和固体聚合物中的有机探针分子的低能光化学反应和高能辐射分解反应可以分析产生的离子的光谱发展速度，从而能够探索宿主修饰对这些系统中发生的独特离子动力学的影响。有机溶剂的小池在沸石的空腔内产生，约束和稳定通常短暂的电荷分离的离子物种，否则这些离子物种将被迅速中和。能量和电荷向固定在固体聚合物主体中的探针分子的迁移是由聚合物的激发引起的。沸石和聚合物系统都有一个共同的特征，即沉积在一个区域的能量快速转移到选定的区域，在目标位置产生化学作用。能量转换、传输和损耗的基本问题是许多重要技术过程的核心。通过研究有机分子与光和高能电子的反应，托马斯教授探索了自由电子、有机自由基(含有奇数个电子的化合物)和有机离子(带有正电荷或负电荷的化合物)的形成和反应机制。正在进行的研究针对的是“宿主”在通过将能量从宿主转移到宿主中的有机分子而在这些活性物种的生成中所起的作用，以及在调节这些活性物种的运输和反应中所起的作用。这些研究揭示了高能激发过程，例如用于x射线光刻的那些过程，其中使用的高分辨率结构，例如在微电子电路生产中，是通过辐射诱导聚合物材料的形成或破坏来产生的。

Supported by the Organic Dynamics Program, Professor Kerry Thomas of the University of Notre Dame studies rapid reactions of ions and radicals in organized and constrained media. Low-energy photochemical and high-energy radiolytic reactions of organic probe molecules held within zeolites and solid polymers permit assay of the rates of development of spectra of the resulting ions, allowing the exploration of the effects of host modification on the unique ion kinetics occurring in these systems. Small pools of organic solvents are created within the cavities of zeolites, constraining and stabilizing usually short-lived charge-separated ionic species which would otherwise be rapidly neutralized. Migration of energy and charge to probe molecules held within solid polymeric hosts is induced by excitation of the polymer. Both the zeolite and the polymer systems share a common feature, the rapid migration of energy deposited in one region to a selected region, creating chemistry at the targeted site. Fundamental questions of energy conversion, transport, and loss are at the heart of many important technological processes. Through an examination of the reactions with light and with high-energy electrons of organic molecules constrained to remain within a tightly-defined `cage` rather than freely moving in solution, Professor Thomas explores the mechanisms of formation and reaction of free electrons, organic radicals (compounds containing an odd number of electrons), and organic ions (compounds bearing either positive or negative charges). Ongoing studies target the role of the `host` both in the generation of these reactive species through the transfer of energy from the host to the organic molecules contained within it and in the moderation of the transport and reactivity of these reactive species. These studies shed light on energetic excitation processes such as those employed in x-ray photolithography, wherein high-resolution structures of use, for example, in microelectronic circuitry production, are produced through the radiation-induced formation or destruction of polymeric materials