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Absolute State-Selected Cross Sections for Ion-Molecule Reactions of Importance in Planetary Ionospheres

行星电离层中重要离子分子反应的绝对状态选择横截面

基本信息

批准号：
9521558
负责人：
Cheuk-Yiu Ng
金额：
$ 24.91万
依托单位：
Iowa State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
1995
资助国家：
美国
起止时间：
1995-09-01 至 1999-08-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9521558&HistoricalAwards=false
关键词：
Absolute State Selected Cross Sections

项目摘要

Many aeronomic techniques depend on knowledge of the cross section for reactions involving singly ionized atomic oxygen. In this project, these cross sections will be measured using a triple-quadropole double octopole (TQDO) mass spectrometer. Significant technical advances have been made in the application of this technique for absolute, total, state-selected cross section measurements. In previous work conducted by the investigators, state-selected beams of ionized oxygen with high purities and intensities were prepared for scattering experiments by controlling the collision energies for dissociative charge transfer collisions of singly ionized helium, neon, and argon with molecular oxygen in a radio frequency (RF) ion guide gas cell, and by applying appropriate effective ion trapping potentials to the RF octopole ion guide. The method also makes use of a differential retarding potential method for improving the kinetic energy resolution of the ionized oxygen reactant ions that are produced by the reactions of molecular oxygen with helium, neon, and argon. Absolute total cross section measurements for the ion-molecule reactions of atomic oxygen with molecular nitrogen, oxygen, hydrogen, carbon dioxide, carbon monoxide, and water are made down to thermal energies using the simple electrostatic aperture of the TQDO apparatus, even though the reactant ions are formed originally with a broad kinetic energy distribution. The investigators will continue these cross section measurements and develop new experimental schemes for absolute cross section measurements of ion-atom reactions relevant to planetary ionospheres.***

许多航空技术依赖于涉及单电离原子氧的反应的截面知识。在这个项目中，这些横截面将使用三重四极双章鱼质谱仪（TQDO）进行测量。该技术在绝对、总、状态选择截面测量中的应用取得了重大的技术进步。在前人的工作中，通过控制单电离氦、氖和氩与分子氧在射频（RF）离子导气池中解离电荷转移碰撞的碰撞能量，并在射频八爪离子导上施加适当的有效离子俘获电位，制备了高纯度、高强度的电离氧状态选择束，用于散射实验。该方法还利用微分缓速势方法来提高由分子氧与氦、氖和氩反应产生的电离氧反应物离子的动能分辨率。原子氧与分子氮、氧、氢、二氧化碳、一氧化碳和水的离子-分子反应的绝对总横截面测量使用TQDO装置的简单静电孔径降为热能，尽管反应物离子最初形成时具有广泛的动能分布。研究人员将继续进行这些横截面测量，并为与行星电离层有关的离子-原子反应的绝对横截面测量开发新的实验方案