| Project/Area Number |
10440202
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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 |
機能・物性・材料
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
OHTANI Bunsho Hokkaido Univ., Catalysis Research Center, Pro., 触媒化学研究センター, 教授 (80176924)
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| Co-Investigator(Kenkyū-buntansha) |
UOSAKI Kohei Hokkaido Univ., Grad. School of Sci., Pro., 大学院・理学研究科, 教授 (20133697)
IKEDA Shigeru Hokkaido Univ., Catalysis Research Center, Inst., 触媒化学研究センター, 助手 (40312417)
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| Project Period (FY) |
1998 – 2000
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| Project Status |
Completed (Fiscal Year 2000)
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| Budget Amount *help |
¥9,300,000 (Direct Cost: ¥9,300,000)
Fiscal Year 2000: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥2,700,000 (Direct Cost: ¥2,700,000)
Fiscal Year 1998: ¥4,000,000 (Direct Cost: ¥4,000,000)
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| Keywords | Semiconductor Suspension / Photocatalysis / Ultrafast Laser / Titanium Dioxide / Anatase / Rutile / Electron-hole recombination / Recombination Rate Constant / 励起子 / ポンププローブ法 |
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| Research Abstract |
This study aimed at clarification of decisive factor of recombination between photoexcited electron and positive hole in the semiconducting materials by analysis of initial process in the photoirradiated titania particles and electrodes with pump-probe time-resolved diffuse reflectance spectroscopy. By using ultrafast femtosecond laser system with 310 nm pump (excitation) and 620 nm probe pulses, we have proved that the bandgap excitation of titania particles induces very fast rise followed by relatively rapid and slow decay of absorption. The rapid decay obeyed second order kinetics suggesting that the absorption is due to trapped electrons and their recombination with positive holes give the rapid decay. Similar behavior was also observed in the electrode of polycrystalline titania showing that each titania particle in the electrode behaves independently. Dependence of these decays on the pump pulse wavelength was investigated for anatase and rutile titania particles. It was clarified that when the particles were photoexcited by the pump pulse of energy close to the bandgaps of crystallites very fast decay component appeared. We concluded that this is due to the formation of excitons.
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