2007 Fiscal Year Final Research Report Summary
Structural Properties of Gas-Phase Solvated Electrons and Anions-Toward the Microscopic Understanding of Stabilization Mechanism-
| Project/Area Number |
18550007
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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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 |
NAGATA Takashi The University of Tokyo, Graduate School of Arts and Sciences, Professor (10164211)
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| Project Period (FY) |
2006 – 2007
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| Keywords | cluster / hydrated electron / valence anion / hydrogen-bonding network / photoelectron spectroscopy / IR photodissociation spectroscopy |
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| Research Abstract |
The aim of the present research project was to attain a microscopic understanding of the stabilization mechanism at play in solvated electrons and anions through the systematic study about the electronic properties of gas-phase cluster anions in heterogeneous solvation environments.
1. Reconstruction of the hydrogen-bonding network in (H_2O)_n^-: We demonstrated that the incorporation of a single D_2O or CH_3OH into (H_2O)_<6,7>^-proceeded efficiently without losing any H_2O constituent, by exploiting the "Ar-mediated" process such as (H_2O)_n^-Ar_m+M→[M・(H_2O)_n^-Ar_m]^†→[(H_2O)_nM]^-+mAr. The photoelectron spectroscopic measurements revealed that isomeric interconversion occurred in [(H_2O)_nM]^-through an extensive reconstruction of the hydrogen-bonding network during the incorporation processes.
2. Formation and photodestruction of dual dipole-bound anion: A new type of dipole-bound anion composed of water and a polar molecule with μ>2.8 D was generated by the incorporation reaction
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of argon-solvated water hexamer anions, (H_2O)_6^-Ar_m. The newly-found anion can be regarded as a dual dipole-bound species described as (H_2O)_6{e^-} M, where the diffuse excess electron interacts with both (H_2O)_6 and M via the individual electron-dipole interaction. The dual dipole-bound anion also serves as a precursor to the hydrated valence anion of M.
3. Structures of [(CO_2)_n(ROH)_m]^-(R=H, CH_3) cluster anions: The solvation structures of [(CO_2)_n(ROH)_m]^-were investigated by infrared photodissociation spectroscopy combined with ab initio calculations. A significant entrainer effect was observed such that the incorporated protic molecule stabilizes CO_2 effectively through the single ionic hydrogen-bonding interaction.
4. Valence anions stabilized by surrounding multi-dipoles: The electronic properties of the negatively-charged clusters of acetone and water molecules, [(Me_2CO)_n(H_2O)_m]^-, were studied by photoelectron imaging spectroscopy. The measurement indicates possibility that a new type of stabilization mechanism is operative in [(Me_2CO)_n(H_2O)_m]^-: i. e., the valence anion of Me_2CO is stabilized by an electrostatic field generated by the surrounding multi-dipoles. Less
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