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

合作研究：低能电子与分子碰撞的实验和理论/计算研究

• 批准号: 0968873
• 负责人: Vincent McKoy
• 金额: $ 2.62万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-10-01 至 2013-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0968873&HistoricalAwards=false
• 关键词: Collaborative; Research; Experimental; Theoretical; Computational

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.

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。该合作包括来自加州州立大学富勒顿分校、加州理工学院、坎皮纳斯州立大学的科学家。它包括实验小组和理论小组，他们聚集在一起，共同努力解决他们有重叠利益和互补专业知识的问题。未来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上的解离电子吸附。多原子学中电子碰撞激发过程的计算和测量是具有挑战性的，尽管需要这样的数据来理解反应等离子体和放电，但结果很少。为了积累这一领域的专业知识，对两个典型的分子--乙烯和呋喃进行了测量和计算，这两个分子都具有与其他阈值很好地隔离的低位三重态。然后，将对甲醇和乙醇的电子碰撞激发截面进行测量和计算。这些典型的和普遍存在的醇类化合物的电子碰撞激发具有基本的意义和高度的技术相关性：解离激发和电离是醇燃料火花点火的关键过程，需要速率数据来模拟和优化点火过程。巴西坎皮纳斯生物乙醇科学和技术中心的合作伙伴正在启动火花点火的研究，包括实验室测量和数值模拟，这些研究将直接利用电子碰撞激发截面，这些截面将作为该项目的一部分进行测量和计算。更广泛的影响是，在低能下的电子-分子碰撞呈现出许多基本感兴趣的特征，对实验和计算方法都构成了巨大的挑战，但它们也具有广泛的技术意义，与等离子体和放电物理、高层大气以及星际和星际介质有关。在甲醇和乙醇的具体情况下，需要准确的主要碰撞过程的截面数据，包括弹性散射、激发和电离，以便对用于点燃用作燃料的醇的放电进行数值模拟和优化。这样的建模可能会导致改进的火花塞设计，从而产生更完整的燃烧，从而提高燃料效率。此外，对醇中电子驱动的激发和解离的理解可能会使我们对相关生物分子(包括糖)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机会，让他们获得在国际背景下从事科学研究的经验，美国学生会延长访问巴西进行研究的时间，反之亦然。