Vibrational Spectroscopy and Reaction Dynamics of Complexes and Reactive Intermediates

配合物和反应中间体的振动光谱和反应动力学

• 批准号: 0096378
• 负责人: Marsha Lester
• 金额: $ 46.63万
• 依托单位: University of Pennsylvania
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0096378&HistoricalAwards=false
• 关键词: Vibrational; Spectroscopy; Reaction; Dynamics; Complexes

Marsha Lester of the University of Pennsylvania is supported by the Experimental Physical Chemistry Program to perform experiments that examine reaction pathways of fundamental chemical reactions, including the reversible reaction of OH + CO to form HOCO with subsequent decomposition to H + carbon dioxide, and the reaction of OH + HCl to form water + Cl. The potential energy surface along the reaction pathway from the entrance channel to the transition state will be mapped via infrared spectroscopy of intra- and inter-molecular vibrational modes of the reactant complexes. The transition state region(s) will also be characterized by vibrational overtone studies of the HOCO reactive intermediate, which will access theoretically predicted predissociative resonances of HOCO. The complexes and reactive intermediates will be generated photolytically, and their vibrational overtone spectra will be obtained using various laser pump-probe methods. The structure and stability of the reactant complexes are expected to reveal their role in the reaction dynamics, and may explain unusual temperature behavior observed for these reactions. Vibrational activation of the complexes and reactive intermediates will supply sufficient energy to induce inelastic and/or reactive scattering dynamics, providing a complementary way to explore the reactive potential energy surfaces. The lifetime of the vibrationally excited complexes and intermediates will be determined by direct time-domain measurements or by spectral line broadening in the frequency domain. Quantum state distributions of inelastically scattered fragments and reaction products will be examined, as well as the branching between these decay processes. Intra-and/or inter-molecular mode selective excitation and isotopic substitution will be utilized to prepare initial states that preferentially decay by chemical reaction. There have been many advances in experimental and theoretical investigations of chemical reaction dynamics over the past decade. These studies focus on directly evaluating the influence of long-range forces on chemical reactions, exploring processes that are of practical importance in atmospheric and combustion chemistry.

宾夕法尼亚大学的玛莎·莱斯特 (Marsha Lester) 在实验物理化学计划的支持下进行实验，检查基本化学反应的反应途径，包括 OH + CO 形成 HOCO 的可逆反应，随后分解为 H + 二氧化碳，以及该反应OH + HCl 形成水 + Cl。 沿反应路径从入口通道到过渡态的势能表面将通过反应物复合物的分子内和分子间振动模式的红外光谱来绘制。 过渡态区域也将通过 HOCO 反应中间体的振动泛音研究来表征，这将获得理论上预测的 HOCO 的预解离共振。 配合物和反应中间体将通过光解产生，并且它们的振动泛音光谱将使用各种激光泵浦探测方法获得。 反应物复合物的结构和稳定性有望揭示它们在反应动力学中的作用，并可以解释在这些反应中观察到的异常温度行为。 复合物和反应性中间体的振动激活将提供足够的能量来诱导非弹性和/或反应性散射动力学，从而提供探索反应性势能表面的补充方式。 振动激发复合物和中间体的寿命将通过直接时域测量或频域中的谱线展宽来确定。 将检查非弹性散射碎片和反应产物的量子态分布，以及这些衰变过程之间的分支。 分子内和/或分子间模式选择性激发和同位素取代将用于制备优先通过化学反应衰变的初始态。过去十年，化学反应动力学的实验和理论研究取得了许多进展。 这些研究重点是直接评估长程力对化学反应的影响，探索在大气和燃烧化学中具有实际意义的过程。