| Project/Area Number |
02453002
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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 |
物理化学一般
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| Research Institution | Tohoku University |
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Principal Investigator |
IKEGAMI Yusaku Tohoku University, institute for Chemical Reaction Science, Professor, 反応化学研究所, 教授 (60006294)
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| Co-Investigator(Kenkyū-buntansha) |
IKOMA Tadaaki Tohoku University, institute for Chemical Reaction Science. Research Associate, 反応化学研究所, 助手 (10212804)
AKIYAMA Kimio Tohoku University, Institute for Chemical Reaction Science, Research Associate, 反応化学研究所, 助手 (10167851)
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| Project Period (FY) |
1990 – 1991
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| Project Status |
Completed (Fiscal Year 1991)
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| Budget Amount *help |
¥6,200,000 (Direct Cost: ¥6,200,000)
Fiscal Year 1991: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 1990: ¥4,800,000 (Direct Cost: ¥4,800,000)
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| Keywords | Time-Resolved EPR Spectroscopy / Energy Transfer with Spin Polarization Conservation / Intermolecular Energy Transfer / Pyridinyl Radicals / Aromatic Ketone / Photochemical Reaction / 光化学反応 / トロポン / 励起三重項状態 / スピン分極 / エネルギ-移動 / 時間分解EPR / 三重項状態 |
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| Research Abstract |
The studies have been carried out to clarify the spin polarization conservation during triplet-triplet energy transfer in fluid solution. This phenomenon first demonstrated by us in 1984 for the photochemical cleavage of the dimers of neutral pyridinyl radicals is important to interpret molecular energy transfer mechanism. The following results have been obtained.
1. Monomer-dimer equilibrium of pyridinyl radicals and its photochemistry. Neutral pyridinyl radicals are substantially in equilibrium with their dimers and the dimers show photochemical cleavage producing the radicals. Time-resolved EPR studies on the initial process disclosed the precursor of photolysis to be the singlet excited state. On the other hand, in the presence of an appropriate triplet sensitizer, triplet-triplet energy transfer with spin polarization conservation occurred leading to the generation of the radical through excited triplet state. Detailed studies on many pyridinyl dimers established a characteristic chemistry of pyridinyl radicals.
2. Spin polarization conservation during the intramolecular triplet-triplet energy transfer. This phenomenon was successfully demonstrated by the measurements of transient triplet EPR spectra for two types of spiran compounds containing energy-donor and acceptor moieties. Spin alignment is conserved in the molecular frame and high field approximation can not explain the spin polarization pattern of the specatra.
3. Other photochemical processes. The photochemical initial processes have been clarified for the following titles : (1) CIDEP studies on radicals produced from photochemical reactions of some aromatic carbonyl compounds ; (2) Time-resolved EPR studies on photochemical hydrogen abstraction reactions of 4-substituted pyridines ; (3) Time-resolved EPR study on the excited triplet state of non-phosphorescent tropone.
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