1995 Fiscal Year Final Research Report Summary
Structures and Dynamics of Negatively-Charged Molecular Clusters
| Project/Area Number |
06453015
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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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, College of Arts and Sciences, Associate professor, 教養学部, 助教授 (10164211)
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| Co-Investigator(Kenkyū-buntansha) |
TSUKUDA Tastuya The University of Tokyo, College of Arts and Sciences, Research assistant, 教養学部, 助手 (90262104)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Molecular cluster anions / Photoelectron spectroscopy / Isomers / Cluster ion-molecule reaction / Charge resonance complex |
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| Research Abstract |
In the present study, we have concentrated our attention to (1) the geometrical and electronic structures and (2) reactivities of negatively-charged molecular clusters :
(1) The electronic structures of [(CO_2)_nROH]^-(R=H,CH_3, and C_2H_5) were investigated by photoelectron spectroscopy. The analysis of the spectra revealed that two forms of isomers coexist in [(CO_2)_nROH]^-(2*n*3) ; one has an electronic structure described as [C_2O_4^-・ROH(CO_2)_<n-2>]where the excess electron is delocalized over two CO_2 molecules, and the other involves a monomer anionic core as [CO_2^-・ROH(CO_2)_<n-1>]. This is one of the few experimental rasults which demonstrates the coexistence of isomers of negatively-charged molecular clusters having defferent electronic structures. The present findings are also supported byab initio calculations at the unrestricted Hatree-Fock levels.
(2) New type of gas-phase reactions involving nagatively-charged molecular clusters were investigated by mass spectrometric technique combined with photoelectron spectroscopy. For example, we have reported reactions of (CO_2)_n^-with CH_3I leading to the formation of a novel molecular anion [CO_2CH_3I]^-, which has not been observed in the corresponding condensed-phase reaction. It turned out that [CO_2CH_3I]^-has a large vertical detachment energy, implyintg that the excess electron is delocalized over [CO_2CH_3I]^-to form an acetate-iodine complex [CH_3CO_2-I]^-. This suggests that (CO_2)_n^-reacts with CH_3I via anucleophilic process. Ab initio calculations are under way to get information on the geometrical and electronic structures of [CO_2CH_3I]^-.
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