Spectroscopy and Dynamics of Ions

Lineberger提出了一项更新建议，利用负离子光电子能谱和离子络合物的超快泵浦-探测激发来研究气相中负离子及其团簇的性质。利用这些技术，可以研究一大类系统的结构信息和反应动力学，这些系统要么是化学瞬变的，要么是活性中间体，要么是过渡态物种。在将要研究的分子中，有有机自由基和双自由基，金属和金属簇合物，以及单分子和双分子过程的过渡态。将获得电子亲和能、单重态-三重态分裂、振动频率和几何信息。将使用立体化学控制来合成邻位、间位和对位形式的苯并(C6H4)。用超快方法研究的单分子过程包括亚乙叉中的1，2氢转移生成乙炔。通过在部分溶剂化离子中电子转移后出现笼中解体和溶剂重组的产物，也将扩大溶剂笼中离子的动力学。这些研究的目标之一是增加对驱动最简单的化学转变的过程的量化理解。通过研究既孤立又被溶剂物种包围的分子的化学转化，Lineberger将能够证明不同的溶剂对反应性以及这些反应进行的速度的影响。

Lineberger has submitted a renewal proposal to investigate the properties of negative ions and their clusters in the gas phase using negative ion photoelectron spectroscopy and ultrafast pump-probe excitation of ionic complexes. With these techniques both the structural information and the reaction dynamics will be investigated for a broad class of systems which are either chemical transients, reactive intermediates, or transition state species. Among the molecules to be studied are organic radicals and biradicals, metals and metal clusters, and transition states for both unimolecular and bimolecular processes. Electron affinities, singlet-triplet splittings, vibrational frequencies, and geometrical information will be obtained. Ortho, meta, and para forms of benzyne (C6H4) will be synthesized using stereochemical control. Unimolecular processes investigated by ultrafast methods include the 1,2 hydrogen shift in vinylidene to form acetylene. The dynamics of ions in a solvent cage will also be extended by following the appearance of products of cage disintegration as well as solvent reorganization following electron transfer in partially solvated ions. One goal of these studies is to increase the quantitative understanding of the processes driving the simplest chemical transformations. By studying the chemical transformations of molecules which are both isolated as well as surrounded by solvent species, Lineberger will be able to demonstrate the effect that different solvents have on reactivity as well as on the rates at which these reactions proceed.