Dynamics of Ion-Radical Collisions: Imaging Studies

在这个由化学系化学结构、动力学和机制计划资助的项目中，罗切斯特大学的James Farrar教授及其研究小组将利用在最初资助期间开发的仪器，采用速度图成像（VMI）方法进行产物检测，探索自由基与原子或分子离子的碰撞。 通过采用自由基（例如CH 3和C3 H5）的脉冲超声源，以及低能阳离子（例如N2+、N+、C+、O2+和O+）和阴离子（例如H-、O-、O2-和OH-）的电子撞击或放电源，VMI检测方法将产生动能和角度的微分截面。特别感兴趣的是产生C-C、C-O、C-N、N-O和H-H键的键形成反应。对于阴离子反应，将检测到由缔合分离产生的自由电子。这些实验将产生有关低能离子与自由基反应动力学的信息，这是离子化学的一个领域，文献中现存的例子很少。 这项工作将解决放电模型的严重缺陷和不包括离子自由基反应的行星大气化学。 H- + H缔合脱附反应的研究将对天体物理学有重要意义。除了表征这些化学系统的动力学，这项研究将提供更深入的了解反应模式和分子的化学反应离子蚀刻发生的理解，并在大气和地球外的化学。仪器技术的发展可能对化学的各个分支学科产生影响，包括质谱和离子成像。参与这项研究的学生和博士后将通过开发新的测量技术，新的高附加值产品和进一步培训科学人员，为国家科学和经济基础设施做出贡献。

In this project supported by the Chemical Structure, Dynamics and Mechanisms Program of the Division of Chemistry, Professor James Farrar of the University of Rochester and his research group will explore the collisions of free radicals and atomic or molecular ions, employing the velocity map imaging (VMI) method for product detection, using the instrument developed during the initial grant period. By employing a pulsed supersonic source of free radicals such as CH3 and C3H5, and an electron impact or discharge source of low energy cations such as N2+, N+, C+, O2+, and O+, and anions such as H-, O-, O2-, and OH-, the VMI detection method will produce differential cross sections in kinetic energy and angle. Of particular interest are the bond formation reactions that yield C-C, C-O, C-N, N-O, and H-H bonds. For anionic reactions, free electrons produced by associative detachment will be detected. The experiments will produce information on the dynamics of reactions of low energy ions with free radicals, an area of ion chemistry with few extant examples in the literature. The work will address the serious deficiencies of models for electrical discharges and the chemistry of planetary atmospheres that do not include ion-radical reactions. A study of the H- + H associative detachment reaction will have important implications for astrophysics. In addition to characterizing the dynamics of these chemical systems, this research will provide a deeper understanding of reactivity patterns and a molecular understanding of the chemistry that takes place in reactive ion etching, and in atmospheric and extraterrestrial chemistry. The instrumental technique development may have impacts in various subdisciplines of chemistry, including mass spectrometry and ion imaging. The students and post-doctoral associates involved in this research will contribute to the national scientific and economic infrastructure through the development of new measurement technologies, new high value-added products, and the further training of scientific personnel.