| Project/Area Number |
16550009
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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 |
Physical chemistry
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| Research Institution | Tokyo Institute of Technology |
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Principal Investigator |
ASANO Motoko s. Tokyo Institute of Technology, Department of Chemistry, Research Associate, 大学院理工学研究科, 助手 (80201888)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | triplet-doublet spin-pair system / spin-spin interaction / photodynamics / porphyrin dimer / time-resolved EPR / pulsed EPR / 常磁性ポルフィリンダイマー / 二中心スピン相互作用 / 光励起状態 / パルスニューテーション |
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| Research Abstract |
Spin multiplicity of the molecular system largely influences its dynamics involving electronic states. In coupled spin systems, the total spin-multiplicity of the system is not simply defined because the two spins are not always coupled enough strongly or weakly to give a single spin-multiplicity. Especially in moderately coupled triplet-doublet system, the degree of mixing of the basis-wavefunctions depends on the angle between the magnetic field and molecular axis due to orientation dependence of dipolar interaction. In a p-bipheyl-linked copper porphyrin-free base porphyrin dimer, the lowest electronic excited state of the dimer is composed of the excited triplet state of the free base and the ground state doublet of the copper porphyrin. Laser irradiation at 532 nm leads to the excitation of the dimer followed by the relaxation to the lowest electronic excited state. Time-resolved EPR spectra in toluene at 40K of this dimer suggest that the observed excited state is a moderately coupled triplet-doublet system. Nutation frequency measurements of partially oriented samples at different magnetic filed positions indicate that spin-multiplicity of the system largely depends on the resonance magnetic field and also the orientation of the molecule relative to the magnetic field.
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