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Solvation structure of iodide on an aqueous solution surface and relevant heterogeneous chemical reactions

水溶液表面碘化物的溶剂化结构及相关非均相化学反应

基本信息

批准号：
19350005
负责人：
MAFUNE Fumitaka
金额：
$ 14.56万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2007
资助国家：
日本
起止时间：
2007 至 2009
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-19350005/
关键词：
気液界面ヨウ化物イオン不均一反応液体ビーム光脱離スペクトル質量分析法吸収スペクトル水溶液表面光脱離多光子励起多光子イオン化質量分析器気体-液体界面濡れ壁法化学イオン化法飛行時間型質量分析器 CTTSバンド

项目摘要

Specific interaction of ions with solvent molecules on a solution surface causes characteristic solvation structures of ions. As solvation structures of halogen ions relate to the heterogeneous chemical reaction of OH radicals in the atmosphere, it is very important to elucidate the solvation structures. First-principles molecular dynamics simulation suggests that iodide ions tend to locate near the surface, whereas chloride ions prefer to be located deep inside the surface.We measured absorption spectrum of iodide ions in the vicinity of the aqueous solution surface : When a NaI aqueous solution is irradiated with a UV light, I- is excited to the CTTS (charge transfer to solvent) state. Then, it is further excited by absorbing another photon and the electron is released from I-. As the electron escape depth from the solution surface is in the order of 1nm, we are able to detect electrons originating from I- located in the vicinity of the surface by the gas phase method. We measured a signal intensity of the electrons as a function of the wavelength of the laser, and found out that I- tends to be located inside the solution at the lower NaI concentration, starting to appear on the surface at the higher NaI concentration. We examined the solvation structures of Na^+ by detecting ions from the surface. It was found that Na^+ tends to be inside the solution regardless of the concentration of NaI.

离子与溶液表面上的溶剂分子的特定相互作用导致离子的特征溶剂化结构。由于卤素离子的溶剂化结构与大气中OH自由基的非均相化学反应有关，因此阐明其溶剂化结构非常重要。第一性原理分子动力学模拟表明，碘离子倾向于位于表面附近，而氯离子更倾向于位于表面深处。我们测量了水溶液表面附近碘离子的吸收光谱：当 NaI 水溶液受到紫外光照射时，I- 被激发到 CTTS（电荷转移到溶剂）状态。然后，它通过吸收另一个光子而被进一步激发，电子从 I- 中释放出来。由于溶液表面的电子逃逸深度为1nm量级，因此我们能够通过气相法检测来自位于表面附近的I-的电子。我们测量了电子信号强度与激光波长的关系，发现 I- 在较低 NaI 浓度时倾向于位于溶液内部，在较高 NaI 浓度时开始出现在表面上。我们通过检测表面离子来检查 Na^+ 的溶剂化结构。研究发现，无论 NaI 浓度如何，Na^+ 都倾向于在溶液内部。