Unraveling the Energetics and Dynamics of Atom-Radical and Radical-Radical Reactions of Atomic Silicon and Silylidyne Radicals with Main Group Hydride Radicals

在化学系的化学结构，动力学和机制-A（CSDM-A）计划和刺激竞争研究的既定计划（EPSCoR）的支持下，Ralf I.夏威夷大学的Kaiser正在使用交叉分子束实验研究最简单的含硅开壳层反应物与原型第二行主族氢化物自由基在单次碰撞条件下形成小的含硅分子的基本原子-自由基和自由基-自由基反应。这些实验是非常具有挑战性的，因为他们的目标是以前未研究的两个开壳瞬态涉及难熔元素硅的双分子反应。Kaiser教授和他的学生将利用最先进的超净交叉分子束机器，在单次碰撞条件下研究双分子原子-自由基和自由基-自由基反应的能量依赖化学动力学。实验结果将与Martin Head-Gordon教授（加州大学伯克利分校）合作，与从头算和准经典轨道计算相结合。这项研究将为培训研究生和本科生提供极好的机会，包括妇女、退伍军人、沿着夏威夷土著人和太平洋岛民，从而鼓励学生在反应动力学方面进行实践研究，并为他们担任教育和研究方面的领导职务做好准备。该项目通过组织硅化学专题讨论会、扩大代表性不足的少数群体的参与、该项目的重点是两种开壳层反应物的基元反应的协同实验和计算研究，其中包括最简单的含硅物质[原子硅（Si）]，和次甲硅烷基（SiH）]和第二列主族氢化物基团[次甲硅烷基（CH）、氨基（NH 2）、羟基（OH）]。这个项目的意义在于，我们的研究提供了新的知识，外来的主族硅化学在分子水平上导致原型双核含硅化合物[Si E; E = C，N，O]沿着与它们的氢化对应物，其中许多只预测理论上存在。这些结果还将提供对潜在化学动力学和反应机制的深入了解，揭示小的含硅系统的化学键合和分子结构，并提供一个框架，用于考虑硅基分子作为星际介质中碳化硅和硅酸盐纳米颗粒的分子构建块。这些研究可能会改变我们对小分子中硅的化学键合、反应性和电子结构的概念以及它们与等价碳对应物的比较的看法。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Structure, Dynamics, and Mechanisms-A (CSDM-A) program in the Division of Chemistry and the Established Program to Stimulate Competitive Research (EPSCoR), Professor Ralf I. Kaiser of the University of Hawaii is using crossed molecular beam experiments to study elementary atom-radical and radical-radical reactions of the simplest silicon-containing open shell reactants with prototype second row main group hydride radicals forming small silicon-bearing molecules under single collision conditions. These experiments are exceptionally challenging since they target previously unstudied bimolecular reactions of two open-shell transients involving the refractory element silicon. Professor Kaiser and his students will investigate the energy-dependent chemical dynamics of the bimolecular atom-radical and radical-radical reactions under single collision conditions utilizing a state-of-the-art, ultra-clean crossed molecular beam machine. The experimental results will be merged with ab initio and quasi classical trajectory calculations in collaboration with Professor Martin Head-Gordon (University of California, Berkeley). This study will provide excellent opportunities for the training of graduate and undergraduate students including women, veterans, along with indigenous Hawaiians and Pacific Islanders, thus encouraging students to do hands-on research in reaction dynamics and preparing them for leadership positions in education and research. This project benefits society by incorporating outreach activities through the organization of a symposium on silicon chemistry, broadening the participation of underrepresented minorities, and enabling educators to incorporate research activities into school and college teaching.This project focuses on synergistic experimental and computational studies of elementary reactions of two open shell reactants comprising the simplest silicon containing species [atomic silicon (Si) and the silylidyne radical (SiH)] and second row main group hydride radicals [methylidyne (CH), amino (NH2), hydroxyl (OH)]. The significance of this project is that our study provides new knowledge on the exotic main group silicon chemistry at the molecular level leading to archetype dinuclear silicon-bearing diatomics [SiE; E = C, N, O] along with their hydrogenated counterparts, of which many have been only predicted to exist theoretically. The results will also provide insight intol the underlying chemical dynamics and reaction mechanisms, expose the chemical bonding and molecular structure of small silicon-bearing systems, and provide a framework for considering silicon-based molecules as molecular building blocks of, for example, silicon carbide and silicate nanoparticles in the interstellar medium. These studies may change our perception on the concepts of chemical bonding, reactivity, and electronic structure of silicon in small molecules and how they compare to the isovalent carbon counterparts.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.