Gas Phase Ion Chemistry and Thermochemistry

在这项由化学系实验物理化学计划资助的提案中，科罗拉多大学的Veronica Bierbaum将继续开展一项关于气相离子-分子反应的动力学、机理和热化学的研究计划。串列流动余辉选择离子流管仪将用于研究过氧化氢、六亚甲基四胺、降冰片二烯和戊二烯的气相离子热化学。亲核取代和消除反应，它们的竞争，溶剂化效应和溶剂动力学同位素效应将被考察。将研究氮和氧与许多不同离子的反应，重点是阴离子化学、新产物离子和同位素交换。用于挥发性有机化合物检测的正、负化学电离技术将扩展到研究挥发性有机化合物的速率常数、分支比、H/D交换和CID碎片模式。该程序收集的大部分热化学数据与重要的燃烧和大气过程有关。地球对流层中高浓度含氧碳氢化合物的来源目前尚不清楚，但它们对大气化学的影响是巨大的。对各种生长和收获植物的生物排放的表征解决了大气化学中的这一关键问题。这项研究的实验结果也将有助于对反应动力学和热化学的基本理解，并将提供有价值的理论比较。

In this proposal funded by the Experimental Physical Chemistry Program of the Chemistry Division, Veronica Bierbaum of the University of Colorado will pursue a program of research on the kinetics, mechanisms, and thermochemistry of gas phase ion-molecule reactions. Tandem flowing afterglow-selected ion flow tube instruments will be used to study the gas-phase ion thermochemistry of peroxyls, hexamethylene tetramine, nobornadiene, and pentalene. Nucleophilic substitution and elimination reactions, their competition, solvation effects, and solvent kinetic isotope effects will be examined. Reactions of nitrogen and oxygen with many different ions will be investigated, with special emphasis on anion chemistry, novel product ions, and isotope exchange. Negative and positive chemical ionization techniques for volatile organic detection will be extended to studying rate constants, branching ratios, H/D exchange and CID fragmentation patterns.Much of the thermochemical data gathered in this program has relevance to important combustion and atmospheric processes. The sources of high concentrations of oxygenated hydrocarbons in the earth's troposphere are not currently understood, but their impact on atmospheric chemistry is significant. The characterization of biogenic emissions from a variety of growing and harvested plants addresses this critical problem in atmospheric chemistry. The experimental results from this research will also contribute to the fundamental understanding of reaction kinetics and thermochemistry and will provide valuable intercomparison with theory.