Molecular Structure and Dynamics Beyond the Born-Oppenheimer Approximation

超越玻恩-奥本海默近似的分子结构和动力学

• 批准号: 9307131
• 负责人: Edward Grant
• 金额: $ 39.92万
• 依托单位: Purdue Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-06-15 至 1997-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9307131&HistoricalAwards=false
• 关键词: Molecular; Structure; Dynamics; Beyond; Born

In this project of the Physical Chemistry Program in the Chemistry Division Prof. E.R. Grant of Purdue University will pursue a program of research on the state-to-state-dynamics of intramolecular relaxation and electron ejection in highly excited small molecules. Specific systems to be investigated are hydrocarbon and metal-centered free radical molecules. Multiple-resonance laser methods will be used to isolate individual transitions that bring the molecules close to their ionization thresholds. Experiments will also be performed to obtain high-resolution information on ionization potentials, photoionization cross sections of free radicals and the rotational-vibrational structure of the corresponding cation, as well as on the vibrational structure of excited electronic states that lie below the adiabatic ionization thresholds. %%% The conventional view of the properties of a polyatomic molecule is based on the Born-Oppenheimer (B-O) approximation according to which its total energy is the sum of independent energies associated with the translational, rotational, vibrational, and electronic degrees of freedom, the actual non-vanishing couplings between these being assumed to be small and negligible in the first approximation. Chemical reactions, however, often involve highly excited electronic and vibrational degrees of freedom and the B-O approximation may be of questionable validity. Processes that involve energies near or above the first ionization threshold, where the dynamics of intramolecular energy relaxation leads in particular to electron ejection, are not amenable to be treated in the B-O approximation. This research concerns fundamental questions about the processes that occur in excited molecular states near the ionization threshold and will provide information suitable for the development of theoretical models of chemical reactivity.

在物理化学项目的这个项目中， 化学部E.R.教授普渡大学的赠款将 进行一项关于国家间动态的研究计划， 分子内弛豫和电子发射 兴奋的小分子。 待调查的具体系统 是碳氢化合物和金属中心的自由基分子。 多共振激光方法将用于分离 使分子接近它们的 电离阈值 还将进行实验， 获得关于电离电势的高分辨率信息， 自由基的光电离截面 相应阳离子的旋转-振动结构， 以及受激电子的振动结构 低于绝热电离阈值的状态。 %%% 传统的观点认为， 分子是基于Born-Oppenheimer（B-O）近似 根据它的总能量是独立的 与平移，旋转， 振动和电子的自由度， 假设这些之间的非零耦合很小 并且在第一近似中可以忽略。 化学反应， 然而，通常涉及高激发电子， 振动自由度和B-O近似可能是 值得怀疑的有效性。 涉及能量接近 或高于第一电离阈值，其中， 分子内能量弛豫特别导致 电子喷射，不适合在B-O中处理 近似 这项研究涉及的基本问题 关于发生在激发态分子中的过程， 电离阈值，并将提供适当信息 化学理论模型的发展 反应性