Theoretical Aspects of Chemical Dynamics: Ion-Molecule Collisions, Energy-Time Analysis of Molecular Spectra, and Assignment of Quantum States

化学动力学的理论方面：离子-分子碰撞、分子光谱的能量-时间分析以及量子态的分配

• 批准号: 9709575
• 负责人: Gregory Ezra
• 金额: --
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2000-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9709575&HistoricalAwards=false
• 关键词: Theoretical; Aspects; Chemical; Dynamics; Ion

Professor Ezra of Cornell University is being supported by the Theoretical and Computational Chemistry program to continue his work on the theoretical investigation of chemical dynamics. Specifically the project is a computational study whereby complex high lying vibrational states are investigated by quantum, classical and semiclassical methods. During this next grant period he will investigate the dynamics of ion-molecule collisions, with particular emphasis on the formation and decay of long lived collision complexes. This research will also focus on the development of semiclassical periodic orbit theory as an aid in the interpretation of molecular vibrational spectra which are of sufficiently high energy that they lie beyond the regime of traditional spectroscopic techniques. These topic address several fundamental problems in chemical and molecular physics namely the fate of energy distribution of long lived molecular complexes and statistical versus non-statistical behavior in the unimolecular decay of transient species. During the following two years Prof. Ezra will be concerned with the theoretical analysis of the internal motions in molecules, as they vibrate, rotate, and collide with one another. The study of these patterns of nuclear motion leads to a deeper understanding of the factors that determine the propensity of molecules to undergo reaction under given conditions. This research group will be studying a number of topics relevant to this general theme. First, they will investigate the nature of the ``sticky'' collisions that can occur between charged species and uncharged molecules in, for example, reactions of atmospheric importance. Such sticky collisions are often essential for subsequent chemical reaction to occur. Another major topic is the development of methods that enable the nature of nuclear motions within molecules to be inferred in a fairly direct way from molecular vibrational spectra. Much of this work exploits semiclassical ideas: that is, theories that are correct with respect to quantum mechanics, while retaining the intuitive appeal of classical ball-and-spring pictures of nuclear motion. Periodic classical motions of nuclei, those that repeat over and over ad infinitum, are found to play an important role in understanding the connection between spectra and nuclear dynamics.

康奈尔大学的Ezra教授正得到理论和计算化学计划的支持，继续他在化学动力学理论研究方面的工作。具体地说，该项目是一项计算研究，利用量子、经典和半经典方法研究复杂的高位振动态。在下一次授予期间，他将研究离子-分子碰撞的动力学，特别强调长寿命碰撞复合体的形成和衰变。这项研究还将重点发展半经典周期轨道理论，作为解释分子振动光谱的辅助工具，分子振动光谱具有足够高的能量，超出了传统光谱技术的范围。这些主题涉及化学和分子物理学中的几个基本问题，即长寿命分子络合物的能量分布的命运以及瞬时物种的单分子衰变中的统计和非统计行为。在接下来的两年里，Ezra教授将致力于分子内部运动的理论分析，当它们振动、旋转和相互碰撞时。对这些原子核运动模式的研究有助于更深入地理解决定分子在特定条件下发生反应的倾向的因素。该研究小组将研究与这一总主题有关的若干专题。首先，他们将研究带电物种和未带电分子之间可能发生的“粘性”碰撞的性质，例如，在具有大气重要性的反应中。这种粘性碰撞往往是后续化学反应发生的关键。另一个主要主题是开发方法，使分子内的核运动的性质能够以相当直接的方式从分子振动光谱中推断出来。这项工作的大部分使用了半经典的想法：也就是，关于量子力学的理论是正确的，同时保留了经典的原子核运动的球弹图像的直观吸引力。原子核的周期性经典运动被发现在理解光谱和核动力学之间的联系中起着重要的作用。