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

这项工作在美国和巴西的几个机构之间继续并进一步发展了一个非常成功的合作，以研究低能电子与多原子分子的相互作用，特别是与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，他们聚集在一起，共同解决他们有重叠的兴趣和互补的专业知识的问题。今后的工作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。多原子中电子冲击激发过程的计算和测量具有挑战性，尽管在理解反应性等离子体和放电方面需要这些数据，但结果却很少。为了建立这一领域的专业知识，对乙烯和呋喃这两种典型分子进行了测量和计算，这两种分子都具有与其他阈值隔离的低洼三重态。然后，测量和计算甲醇和乙醇的电子冲击激发截面。这些原型和普遍存在的醇类的电子冲击激发具有重要意义，也具有很高的技术相关性：解离激发和电离是醇类燃料火花点火的关键过程，并且需要速率数据来建模和优化点火过程。位于巴西坎皮纳斯的生物乙醇科学技术中心的合作者正在启动火花点火的研究，该研究将涉及实验室测量和数值模拟，这些研究将直接利用电子冲击激发截面，作为该项目的一部分，这些截面将被测量和计算。更广泛的影响是，低能电子-分子碰撞呈现出许多基本的兴趣特征，对实验和计算方法都提出了巨大的挑战，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、星周和星际介质的物理学有关。在甲醇和乙醇的具体情况下，需要精确的主要碰撞过程的截面数据，包括弹性散射、激发和电离，以进行数值模拟和优化用于点燃用作燃料的酒精的放电。这样的建模可以改进火花塞的设计，使燃烧更彻底，从而提高燃油效率。此外，对醇类中电子驱动的激发和解离的理解可能会对包括糖在内的相关生物分子的相同过程有深入的了解。该项目的一个核心组成部分是为年轻科学家提供获得在国际背景下从事科学研究的经验的机会，美国学生可以长期访问巴西进行研究，反之亦然。本项目由国际科学与工程办公室美洲项目共同资助。

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. This project is co-funded with the Americas Program of the Office of International Science and Engineering.