| Project/Area Number |
12640554
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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 |
機能・物性・材料
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| Research Institution | Japan Advanced Institute of Science and Technology |
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Principal Investigator |
YOSHIHARA Keitaro School of Materials Science, Professor, 材料科学研究科, 教授 (40087507)
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| Co-Investigator(Kenkyū-buntansha) |
KUMAZAKI Shigeichi School of Materials Science, Associate, 材料科学研究科, 助手 (40293401)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2001: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2000: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | spectral sensitization / photography / AgBr / electron injection / energy transfer / ultrafast spectroscopy / super-sensitization / fluorescence measurement / 分光増感 / 電子移動 / 銀塩 / 色素増感 / 結晶系 / 色増感 / フェムト秒分光 / 吸着色素 / 蛍光寿命 |
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| Research Abstract |
Spectral sensitization and supersensitization of the silver bromide nanocrystals were studied in the femtosecond timescale for the first time. An annihilation-free fluorescence from J-aggregates of dye 1 adsorbed on the silver bromide nanocrystals (edge to edge distance from 40 to 900 nm) of different shapes (cubic and octahedral) was measured [1]. Very fast non-exponential fluorescence decays were observed with a fast component from 0.4 to 2.5 ps, and an average decay time from 1.1 to 5.5 ps, depending on the type and size of AgBr grains. The average fluorescence decay time is several times longer on the cubic grains than that on the octahedral grains.
By time-resolved fluorescence anisotropy measurement the ultrafast excitation-energy transfer of the J-aggregates on the octahedral AgBr microcrystal is studied [2]. The anisotropy decays are biphasic with two time constants of 〜0.15 ps and 2-7 ps. The short time constant is almost independent of the dye coverage, while the second one becomes slower at higher dye coverages. An ultrafast excitation transfer (O.1ps) is suggested to take place between epitaxially arranged J-aggregates on the {111} surface prior to the primary electron injection to AgBr (0.7 ps).
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