Transient Intermediates in the Gas Phase

气相瞬态中间体

• 批准号: 9712570
• 负责人: Frantisek Turecek
• 金额: $ 29.65万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-12-01 至 2001-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9712570&HistoricalAwards=false
• 关键词: Transient; Intermediates; Gas; Phase

Professor Frantisek Turecek, of the Department of Chemistry at the University of Washington, is supported by the Organic and Macromolecular Chemistry Program for his studies of the formation and properties of transient intermediates in chemical reactions in the gas phase. Molecules and radicals of sulfur oxyacids and nitroalkane radicals relevant to tropospheric oxidations, and intermediates in the addition of hydrogen atoms and hydroxyl radicals to nucleic bases, are generated by fast neutralization of cations and anions and studied by neutralization-reionization mass spectrometry. These studies, combined with complementary ab initio, density-functional theory, and RRKM calculations, address the stabilities of these transient intermediates in their ground and excited states and permit the analysis of their energetics and the kinetics of their unimolecular dissociation. Chemical reactions often proceed by consecutive elementary steps, each generating a transient and reactive intermediate. Characterization of such intermediates represents a formidable experimental challenge given their typically short lifetimes and low concentrations. An especially challenging class of transient intermediates to study is comprised of those formed by high-energy processes such as those that occur in the stratosphere and troposphere, in combustion, and in radiolysis by ionizing radiation. With the support of the Organic and Macromolecular Chemistry Program, Professor Frantisek Turecek, of the Department of Chemistry at the University of Washington, studies the formation and properties of transient intermediates in chemical reactions in the gas phase. Professor Turecek uses neutralization-reionization mass spectrometry, a `non-chemical` technique, for the production of the desired intermediates from simple precursor ions, avoiding the structural ambiguities which can result from their attempted production by other means. These studies, complemented by computational analyses, address the stabilities and reactivity of these transient intermediates, shedding light on the fundamental events which occur during high-energy processes.

华盛顿大学化学系的 Frantisek Turecek 教授获得有机和高分子化学项目的支持，研究气相化学反应中瞬态中间体的形成和性质。 与对流层氧化相关的硫含氧酸和硝基烷自由基的分子和自由基，以及氢原子和羟基自由基与核酸碱基加成的中间体，是通过阳离子和阴离子的快速中和产生的，并通过中和-再电离质谱法进行研究。 这些研究与互补的从头算、密度泛函理论和 RRKM 计算相结合，解决了这些瞬态中间体在基态和激发态的稳定性，并允许分析它们的能量学和单分子解离动力学。 化学反应通常通过连续的基本步骤进行，每个步骤都会产生瞬态和反应性中间体。 鉴于此类中间体的寿命通常较短且浓度较低，对其进行表征是一项艰巨的实验挑战。 要研究的一类特别具有挑战性的瞬态中间体是由高能过程形成的，例如平流层和对流层、燃烧以及电离辐射的辐射分解中发生的那些。 在有机与高分子化学项目的支持下，华盛顿大学化学系的Frantisek Turecek教授研究了气相化学反应中瞬态中间体的形成和性质。 Turecek 教授使用中和-再电离质谱法（一种“非化学”技术）从简单的前体离子生产所需的中间体，避免了由于尝试通过其他方式生产而可能导致的结构模糊性。 这些研究辅以计算分析，解决了这些瞬态中间体的稳定性和反应性，揭示了高能过程中发生的基本事件。