Dynamical Resonances in Chemical Reactions and Chemical Bonding

化学反应和化学键合中的动态共振

• 批准号: 8810557
• 负责人: James Valentini
• 金额: $ 37.19万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-06-01 至 1991-02-19
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8810557&HistoricalAwards=false
• 关键词: Dynamical; Resonances; Chemical; Reactions; Bonding

Dr. Valentini is supported by a grant fom The Physical Chemistry Program to study the structure and dynamics of transition states in gas phase chemical reactions. Valentini has developed a spectroscopic technique which permits the indirect observation of the short-lived intermediates (transition states) which have long been theoretically predicted but never observed in chemical reactions. Dr. Valentini's research involves the studies of so-called Feshbach resonances in rotational excitation cross sections which are observed for chemical reactions in the gas phase. The direct observations involve state-to-state dynamics in which the vibrational and rotational quantum states (v,j) of the reactants are prepared by free-jet expansion cooling and probed by stimulated Raman excitation. The collision energy of the reactants is selected, varied, and precisely specified through laser photolysis of a diatomic precursor to generate the reactant atom. Vibrational and rotational (v',j') analysis of the reaction products under single collision conditions are effected using resonance-enhanced multiphoton ionizaiton. Dr. Valentini's research program is motivated by his recent discovery of Feschbach resonances in the ortho-, para-hydrogen exchange reaction. This observation permitted him to infer the vibrational energy states of the linear triatomic transition state which occurs in this reaction. Further studies in this area will involve the hydrogen deuterium exchange reaction, the reaction of chlorine with hydrogen chloride, and the reaction of iodine and bromine with their corresponding hydrogen halides. Coherent Raman spectra of these species will be obtained to elucidate the nature of the theoretically predicted vibrational bonding.

Valentini 博士得到物理化学项目的资助，用于研究气相化学反应中过渡态的结构和动力学。 瓦伦蒂尼开发了一种光谱技术，可以间接观察短暂的中间体（过渡态），这些中间体长期以来一直在理论上预测，但从未在化学反应中观察到。 Valentini 博士的研究涉及旋转激发截面中所谓的 Feshbach 共振的研究，该共振可在气相化学反应中观察到。 直接观察涉及状态到状态动力学，其中反应物的振动和旋转量子态 (v,j) 通过自由射流膨胀冷却来制备，并通过受激拉曼激发进行探测。 通过双原子前体的激光光解来选择、改变和精确指定反应物的碰撞能量以生成反应物原子。 使用共振增强多光子电离对单次碰撞条件下的反应产物进行振动和旋转 (v',j') 分析。 Valentini 博士的研究计划源于他最近在邻位、仲位氢交换反应中发现的费施巴赫共振。 这一观察使他能够推断出该反应中发生的线性三原子过渡态的振动能态。 该领域的进一步研究将涉及氢氘交换反应、氯与氯化氢的反应以及碘和溴与其相应卤化氢的反应。 将获得这些物质的相干拉曼光谱，以阐明理论上预测的振动键合的性质。