2009 Fiscal Year Final Research Report
Solvation structure of iodide on an aqueous solution surface and relevant heterogeneous chemical reactions
| Project/Area Number |
19350005
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Physical chemistry
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MAFUNE Fumitaka The University of Tokyo, 大学院・総合文化研究科, 准教授 (50262142)
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| Co-Investigator(Kenkyū-buntansha) |
HIROKAWA Jun 北海道大学, 大学院・地球環境科学研究院, 准教授 (20262115)
MIYAJIMA Ken 東京大学, 大学院・総合文化研究科, 助教 (20365456)
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| Project Period (FY) |
2007 – 2009
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| Keywords | 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 |
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| Research Abstract |
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.
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