Collaborative Research: Experimental and Theoretical/Computational Studies of Low Energy Electron Collisions with Molecules

这项工作继续并进一步发展了美国和巴西几个机构之间非常成功的合作，以研究低能电子与多原子分子，特别是生物燃料和其他生物分子的相互作用。这项合作包括来自加州州立大学富勒顿分校、加州理工学院和坎皮纳斯州立大学的科学家。它涉及实验和理论小组谁走到一起，共同努力的问题，他们有重叠的利益和互补的专业知识。未来工作的重点将是多原子分子的电子碰撞激发和多原子分子的解离电子附着。在多原子电子碰撞激发过程的计算和测量是具有挑战性的，结果是稀缺的，尽管需要这样的数据在理解反应等离子体和放电。为了建立在这一领域的专业知识，测量和计算进行了两个原型分子，乙烯和呋喃，这两个都有低洼的三重态，以及从其他阈值隔离。接着，测量和计算了甲醇和乙醇的电子碰撞激发截面。电子碰撞激发这些原型和无处不在的醇是根本的利益，也有很高的技术相关性：解离激发和电离的醇燃料的火花点火的关键过程，和速率数据需要建模和优化的点火过程。巴西坎皮纳斯生物乙醇科学和技术中心的合作者正在启动火花点火研究，这将涉及实验室测量和数值建模，这些研究将直接利用电子碰撞激发截面，这些截面将作为本项目的一部分进行测量和计算。低能量下的分子碰撞呈现出许多基本感兴趣的特征，并对实验和计算方法提出了巨大的挑战，但它们也具有广泛的技术意义，与等离子体和放电，高层大气，以及星周和星际介质。在甲醇和乙醇的具体情况下，准确的横截面数据的主要碰撞过程，包括弹性散射，激发和电离，需要用于点燃酒精作为燃料的放电的数值模拟和优化。这样的建模可以导致改进的火花塞设计，其产生更完全的燃烧并且因此产生更高的燃料效率。此外，对醇类中电子驱动的激发和解离的理解可能会让我们深入了解相关生物分子（包括糖）中的相同过程。该项目的一个核心组成部分是为年轻科学家提供机会，让他们在国际环境中获得科学经验，美国学生可以在巴西进行长期访问，反之亦然。

This work continues and further develops a highly successful collaboration among several institutions in the US and Brazil to investigate the interactions of low-energy electrons with polyatomic molecules, and in particular with biofuels and other biological molecules. The collaboration includes scientists from California State University, Fullerton, the California Institute of Technology, the State University of Campinas. It involves both experimental and theoretical groups who have come together to work jointly on problems where they have overlapping interests and complementary expertise. Major focuses in future work will be electron-impact excitation of polyatomic molecules and dissociative electron attachment to polyatomics. Calculations and measurements of electron-impact excitation processes in polyatomics are challenging, and results are scarce despite the need for such data in understanding reactive plasmas and discharges. To build expertise in this area, measurements and calculations are carried out for two prototypical molecules, ethylene and furan, both of which have low-lying triplet states well isolated from other thresholds. Following that, measurements and calculations of electron-impact excitation cross sections for methanol and ethanol will be done. Electron-impact excitation of these prototypical and ubiquitous alcohols is of fundamental interest and also has high technological relevance: dissociative excitation and ionization are key processes in spark ignition of alcohol fuels, and rate data are needed for modeling and optimizing the ignition process. Collaborators in Brazil affiliated with the Bioethanol Science and Technology Center in Campinas are initiating studies of spark ignition that will involve both laboratory measurements and numerical modeling, and those studies will make direct use of the electron-impact excitation cross sections that will be measured and calculated as part of this project.The broader impacts are that electron-molecule collisions at low energy present many features of fundamental interest and pose a great challenge to both experimental and computational methods, but they also have wide technological significance, being relevant to the physics of plasmas and discharges, the upper atmosphere, and circumstellar and interstellar media. In the specific case of methanol and ethanol, accurate cross-section data for the major collision processes, including elastic scattering, excitation, and ionization, are needed for numerical modeling and optimization of discharges used to ignite alcohols used as fuels. Such modeling may lead to improved spark-plug designs that produce more complete combustion and thus higher fuel efficiency. Moreover, an understanding of electron driven excitation and dissociation in the alcohols may give insights into the same processes in related biomolecules, including sugars. A central component of the project is providing opportunities for young scientists to gain experience doing science in an international context, with US students making extended visits to do research in Brazil and vice versa.