| Project/Area Number |
10440164
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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 | TOHOKU UNIVERSITY |
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Principal Investigator |
MURAI Hisao TOHOKU UNIVERSITY, GRADUATE SCHOOL OF SCIENCE, ASSOCIATE PROFESSOR, 大学院・理学研究科, 助教授 (50142261)
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| Co-Investigator(Kenkyū-buntansha) |
MAEDA Kiminori DEPARTMENT OF CHEMISTRY, TSUKUBA UNIVERSITY, LECTURER, 化学系, 講師 (70229300)
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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 |
¥15,300,000 (Direct Cost: ¥15,300,000)
Fiscal Year 2000: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 1998: ¥7,100,000 (Direct Cost: ¥7,100,000)
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| Keywords | Transient Absorption Detected Magnetic Resonance / Reaction Control / SDS Micelle / Tetraphenylhydrazine / Radical Pair / Quantum Beat / Spin Chemistry / Spin Locking / 磁場効果 / マイクロ波効果 / スピンダイナミックス / 磁場ジャンプ / 過渡吸収検出磁気共鳴法 / ラジカル対 / RYDMR / TMDPO |
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| Research Abstract |
This project aims at the observation and deep investigation of the spin coherent phenomenon of radical pairs formed transiently by photochemical method. We employed two different methods under the existence of radical pairs : 1) sudden jumping of the external magnetic field, 2) quick switching of the electromagnetic field (microwave field) under the conditions of the electron spin resonance. The radical pairs are prepared using a laser pulse irradiation to several solutions. The systems we employed were a) polymethylene-linked biradical, b) radical-ion pairs formed by photoinduced electron transfer reaction, c) micellar systems that include transiently formed radical pairs. Method 1) was applied to the the system b) and it showed the controlled reaction by the magnetic field jump, but we realized the difficulty of the theoretical handling of low magnetic field phenomenon. This study is still under investigation. Method 2) provided many new discoveries about the spin dynamics of radical pair and radical-ion pair systems. First of all, we succeeded in observing the different spin quantum beats of several radical pair systems. The beat data showed the double tequency signal due to simultaneous excitation of the component radicals of radical pairs by microwave field. The decay of the beat signal was proved to be due to the triplet-triplet dephasing phenomenon probably induced by anisotropic dipole-dipole interaction in the radical pair. Another important finding is the appearance of a broadened spectral pattern under the strong microwave field, that was also rationalized by the spin dephasing effect. This project apparently demonstrated that the switching of the external field and/or the electromagnetic alternating field can control the chemical reaction pathways and it also provides a lot of important information about the spin and chemical dynamics of photochemical systems.
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