Vibrational Spectroscopy of Ion Solvent Clusters

离子溶剂簇的振动光谱

• 批准号: 9700610
• 负责人: Mitchio Okumura
• 金额: $ 35.71万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2001-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9700610&HistoricalAwards=false
• 关键词: Vibrational; Spectroscopy; Ion; Solvent; Clusters

The Experimental Physical Chemistry Program supports Mitchio Okumura of California Institute of Technology in his continuing studies on anionic cluster solvation. Specifically, he uses vibrational predissociation spectroscopy to study the structure of various anions hydrated with `n` molecules of water, as a function of n. Apparently, experimental studies on cationic hydrate clusters and anions clustered with rare gases indicate that solvation shells form and the ion is in the interior. Theoretical work on halide anionic hydrate clusters suggest, on the other hand, that the ion is bound to the surface of clustered water molecules, and as the cluster size increases, a transition from surface- to interior-solvation occurs. Okumura will focus on the hydrogen stretching region; the frequency shifts and linewidths in this region should yield insight on hydrogen bonding both between ion and solvent molecules and among solvent molecules. In addition, two photon (infrared-infrared double resonance predissociation or infrared-ultraviolet vibrationally assisted photodetachment) spectroscopy will be brought to bear on those clusters that are more strongly bound. Finally, cluster solvation of acids implicated in stratospheric aerosol chemistry will be investigated. An ab initio theoretical effort will be carried out to aid in determining cluster geometries. While the aim of this work is to investigate ion-solvent interactions at a fundamental level, a second motivation is to elucidate solvation processes and ionic reaction mechanisms of relevance to atmospheric chemistry. Many of the systems that will be investigated play central roles in heterogeneous reactions occuring in the stratosphere and troposphere. Adducts of these ionic hydrates with atmospheric species such as nitric acid and hydrochloric acid may serve as models of intermediates in the adsorption and ionic dissociation on atmospheric aerosols.

实验物理化学计划支持加利福尼亚理工学院的Mitchio Okumura在他对阴离子簇溶剂化的持续研究中。 具体而言，他使用振动预分离光谱法研究了用水的n n n n n n'水分的各种阴离子的结构，作为n的函数。 显然，对阳离子水合物簇和用稀有气体聚集的阴离子的实验研究表明，溶剂化壳形成，离子在内部。 另一方面，卤化物阴离子水合物簇上的理论工作表明，离子与簇水分子的表面结合，并且随着簇的大小的增加，从表面到内部溶解的过渡会发生。 Okumura将专注于氢拉伸区。该区域中的频移和线宽应对离子和溶剂分子之间以及溶剂分子之间的氢键产生见解。 此外，两个光子（红外红外共振前置或红外 - 脱离硫化物振动辅助光检查）光谱将被带到那些更强结合的群集上。 最后，将研究与平流层气溶胶化学有关的酸的簇溶剂化。 从头开始的理论努力将有助于确定簇几何形状。 尽管这项工作的目的是在基本水平上研究离子 - 溶剂相互作用，但第二个动机是阐明与大气化学相关的溶剂化过程和离子反应机制。 将研究的许多系统在平流层和对流层中发生的异质反应中起着核心作用。 这些离子水合物与大气种类（如硝酸和盐酸）的加合物可以用作大气气溶胶吸附和离子解离的中间体模型。