Spectroscopy and Reaction Dynamics of Activated Entrance Channel Complexes

激活的入口通道复合物的光谱学和反应动力学

• 批准号: 9729234
• 负责人: Marsha Lester
• 金额: $ 43.98万
• 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: 1998
• 资助国家: 美国
• 起止时间: 1998-03-15 至 2001-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9729234&HistoricalAwards=false
• 关键词: Spectroscopy; Reaction; Dynamics; Activated; Entrance

Marsha Lester of the University of Pennsylvania is supported by the Experimental Physical Chemistry Program in her ongoing studies to characterize the intermolecular potential, inelastic scattering and reaction dynamics of vibrationally activated entrance channel complexes composed of a hydroxyl radical and a reactive molecular partner (carbon monoxide, nitric oxide, water). Infrared excitation will provide sufficient energy to overcome the activation barrier to reaction while intermolecular excitations will orient the reactants such that the structure of the complex approximates that of the transition state. Prof. Lester will use double resonance techniques to record the mid- and near-IR spectra of the OH stretch as well as intermolecular bending levels of the OH complexes. Spectral measurements should yield information on the potential energy surfaces in the entrance channel to reaction for ground state and vibrationally excited reactants. The hydroxyl radical plays a pivotal role in the chemistry of the lower atmosphere. It is known as the `atmosphere's detergent` because its reactions prevent the accumulation of most trace gases in the atmosphere, many of which would act as air pollutants and greenhouse gases. For the majority of hydrogen-containing molecules emitted into the troposphere, reaction with the OH radical is their major, if not sole, chemical loss process. Thus, reaction with OH radicals leads to the removal of these compounds from the atmosphere and limits their atmospheric concentrations. Much experimental work has already been performed to evaluate the OH radical kinetics and reaction mechanisms under the conditions encountered in the atmosphere. In these studies, Prof. Lester will use techniques developed in her laboratory to take a much closer look at the reactions dynamics of OH radicals with molecular partners of atmospheric relevance such as carbon monoxide, nitric oxide and water.

宾夕法尼亚大学的玛莎·莱斯特 (Marsha Lester) 得到了实验物理化学项目的支持，她正在进行的研究旨在表征由羟基自由基和反应性分子伴侣（一氧化碳、一氧化氮、水）。 红外激发将提供足够的能量来克服反应的活化势垒，而分子间激发将使反应物定向，使得络合物的结构接近过渡态的结构。 Lester 教授将使用双共振技术来记录 OH 拉伸的中红外光谱和近红外光谱以及 OH 配合物的分子间弯曲水平。 光谱测量应产生有关基态和振动激发反应物反应入口通道中势能表面的信息。 羟基自由基在低层大气的化学中起着关键作用。 它被称为“大气的清洁剂”，因为它的反应可以防止大多数微量气体在大气中积聚，其中许多微量气体会成为空气污染物和温室气体。 对于大多数排放到对流层的含氢分子来说，与 OH 自由基的反应是它们主要的（如果不是唯一的）化学损失过程。 因此，与 OH 自由基的反应导致这些化合物从大气中去除并限制它们的大气浓度。 已经进行了大量的实验工作来评估大气条件下的 OH 自由基动力学和反应机制。 在这些研究中，莱斯特教授将利用她实验室开发的技术，更仔细地研究 OH 自由基与大气相关分子伙伴（如一氧化碳、一氧化氮和水）的反应动力学。