2003 Fiscal Year Final Research Report Summary
Formation and decay of superexcited molecules as studied by synchrotron-radiation photon and electron collisions
| Project/Area Number |
13440175
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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 | Tokyo Institute of Technology |
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Principal Investigator |
NORIYUKI Kouchi Tokyo Institute of Technology, Graduate School of Science and Engineering, Professor, 大学院・理工学研究科, 教授 (50161873)
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| Co-Investigator(Kenkyū-buntansha) |
ODAGIRI Takeshi Tokyo Institute of Technology, Graduate School of Science and Engineering, Assistant, 大学院・理工学研究科, 助手 (80282820)
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| Project Period (FY) |
2001 – 2003
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| Keywords | superexcited molecules / doubly excited molecules / synchrotron radiation / electron collisions / electron energy-loss spectroscopy / coincidence measurements / fluorescence / neutral dissociation |
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| Research Abstract |
1.Doubly excited molecules as studied by synchrotron-radiation photon collisions
We have measured the absolute values of the cross sections for the emission of fluorescences in the ultraviolet and visible ranges from neutral fragments in the photoexcitation of methane, ammonia, water and ethylene as a function of incident photon energy in the range 10-40 eV. Interestingly, the oscillator strengths for Balmer fluorescences from doubly excited methane, ammonia and water in the inner valence range amount to the magnitudes comparable to those from nearby single-hole one-electron superexcited states of these molecules, which is a strong indication of the breakdown of the independent electron model. An important role of the doubly excited ethylene has been found in the cross section curves for Balmer fluorescences.
2.Superexcited molecules as studied by the coincident electron-energy-loss spectroscopy
The coincident electron-energy-loss spectroscopy is an excellent means for investigating the s
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uperexcited molecules, which was developed by our group a few years ago. The electron energy-loss spectra are measured in coincidence with the emission of the vacuum-ultraviolet fluorescences from neutral fragments in electron collisions with molecules, in which the structures attributed to the superexcited states are shown up. We have measured the coincident electron-energy-loss spectra of molecular nitrogen, molecular oxygen, and methane in the valence range at several incident electron energies and scattering angles. Interestingly the optically-forbidden doubly excited states of nitrogen give larger contribution than the allowed doubly excited states. The time-resolved coincident electron-energy-loss spectra of oxygen have been measured to study the superexcited oxygen molecules in detail. The intense peaks attributed to the doubly excited methane have been found in the range above 25 eV. The second-generation system equipped with a position-sensitive detector for electrons has been developed to obtain the spectra much more efficiently Less
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