2000 Fiscal Year Final Research Report Summary
Investigation on Initial Process of Photoexcitation at Semiconductor/Solution Interface by Ultrafast Spectroscopy
| 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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| Keywords | Semiconductor Suspension / Photocatalysis / Ultrafast Laser / Titanium Dioxide / Anatase / Rutile / Electron-hole recombination / Recombination Rate Constant |
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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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[Publications] Ohtani, B., Kominami, H., Bowman, R.M., Colombo Jr., P., Noguchi, H.and Uosaki, K.: "Femtosecond Diffuse Reflectance Spectroscopy of Aqueous Titanium (IV) Oxide Suspension : Correlation of Electron-Hole Recombination Kinetics with Photocatalytic Activity"Chem. Lett.. 579-580 (1998)
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「研究成果報告書概要(欧文)」より
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[Publications] Kominami, H., Kato, J.-i., Murakami, S.-y., Kera, Y., Inoue, M., Inui, T.and Ohtani, B.: "Synthesis of Titanium (IV) Oxide of Ultra-high Photocatalytic Activity : High-temperature Hydrolysis of Titanium Alkoxides with Water Liberated Homogeneously from Solvent Alcohols"J.Mol. Catal., A.Chem.. 144. 165-171 (1999)
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[Publications] Kominami, H., Kato, J.-i., Murakami, S.-y., Kohno, M., Kera, Y., Nishimoto, S.-i., Inoue, M., Inui, T.and Ohtani, B.: "Thermal Treatment of Titanium Alkoxides in Organic Media : Novel Synthesis Methods for Titanium (IV) Oxide Photocatalyst of Ultra-high Activity"Stud. Surf. Sci. Catal.. 130. 1937-1942 (2000)
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「研究成果報告書概要(欧文)」より
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[Publications] Ikeda, S., Sugiyama, N., Pal, B., Marci, G., Palmisano, L., Noguchi, H., Uosaki, K.and Ohtani, B.: "Photocatalytic Activity of Transition-Metal-Loaded Titanium (IV) Oxide Powders Suspended in Aqueous Solutions : Correlation with Electron-Hole Recombination Kinetics"Phys. Chem. Chem. Phys.. 3. 267-273 (2001)
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[Publications] Kominami, H., Oki, K., Kohno, M., Onoue, S.-i., Kera, Y.and Ohtani, B.: "Novel Solvothermal Synthesis of Niobium (V) Oxide Powders and Their Photocatalytic Activity in Aqueous Suspensions"J.Mater. Chem.. 11. 604-609 (2001)
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