Flowing Afterglow and SIFT-Drift Studies of Gas Phase Ion-Molecule Reactions

该项目属于有机动力学项目，涉及科罗拉多大学C. De Puy和V. Bierbaum的持续工作。它们将在高真空下通过电子冲击产生高活性的离子，并通过质谱法观察这些离子与中性分子碰撞产生的反应。通过消除存在于缩合相反应中的溶剂化效应，这将有助于更好地理解有机离子反应。本文将研究在流动余辉中离子与中性分子的反应。离子将通过电子冲击或离子合成反应等其他方法产生，在四极质量过滤器中与其他离子和中性前体分离，并与0.5 torr的氦气一起注入流管。高活性离子，例如CH阴离子，将被允许与各种中性试剂反应，以便与更常规的反应物离子比较它们的反应速率和产物通道。同位素标记的离子，特别是那些含有S-34、Cl-37、O-18和C-13的离子，将被用作示踪剂，以检查反应速率，否则这些反应将被隐藏，例如在HS-34阴离子和硫化氢（S-32）之间的反应。预计在星际介质中出现的带正电的碳氢化合物阳离子将被允许与已知存在于太空中的分子（例如水）发生反应，以试图了解在不寻常的太空条件下有机分子的起源。极弱酸性分子的酸度，如胺、杂芳香族化合物和烷烃，将通过硅烷的化学反应来探测。总体目标是通过消除溶剂化的模糊效应来了解简单有机离子反应的细节。

This project, within the Organic Dynamics Program, involves the continuing work of C. De Puy and V. Bierbaum of the University of Colorado. They will generate highly reactive, ionic species by electron impact under high vacuum, and observe, by mass spectrometry, reactions resulting from the collision of these ions with neutral molecules. This will lead to a better understanding of organic ionic reactions by removing the effects of solvation which are present in condensed phase reactions. Reactions between ions and neutral molecules in a flowing afterglow selected ion flow tube apparatus will be studied. Ions will be generated by electron impact or by other methods including ion synthesis reactions, separated from other ions and neutral precursors in a quadrupole mass filter and injected into a flow tube together with 0.5 torr of helium. Highly reactive ions, as for example CH anion, will be allowed to react with a variety of neutral reagents in order to compare their reaction rates and product channels with more conventional reactant ions. Isotopically labeled ions, particularly those containing S-34, Cl-37, O-18 and C-13, will be used as tracers to examine rates for reactions which would otherwise be hidden as in, for example, that between HS-34 anion and hydrogen sulfide (S-32). Positively charged hydrocarbon cations which are expected to occur in the interstellar medium will be allowed to react with molecules (e.g., water) known to be present in space in an attempt to understand the origin of organic molecules under the unusual conditions of space. The acidity of very weakly acidic molecules, for example amines, heteroaromatic compounds and alkanes, will be probed by chemical reactions of silanes. The overall goal is to understand the details of simple organic ionic reactions by removing the obscuring effects of solvation.