1997 Fiscal Year Final Research Report Summary
Measurement of ESR Relaxation Time at Low Magnetic Fields
| Project/Area Number |
08554027
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
機能・物性・材料
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| Research Institution | University of Tsukuba |
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Principal Investigator |
IKEDA Ryuichi University of Tsukuba, Department of Chemistyry, Professor, 化学系, 教授 (90022631)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIMARU Shin-ichi University of Tsukuba, Department of Chemistyry, Assistant, 化学系, 助手 (10251034)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Overhauser Effect / Electron-Nuclear Double Resonance / Unpaired Electron Spin / Electron Spin Diffusion |
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| Research Abstract |
We designed and constructed a new electron-nuclear double resonance spectrometer based on the Overhauser effect to investigate the mechanism of the long-range diffusion of unpaired electrons formed in halogen-bridged one-dimensional mixed valence complexes. In this project, we utilized the strong NMR signals obtained by saturating the ESR signals using a strong microwave radiation on the sample and extended the field dependency of relaxation times to the low-field region.
In the design of the electron-nuclear double resonance spectrometer, we used the microwave oscillator in our ESR spectrometer operative between 8,800 to 9,800 MHz. By leading this output to a newly purchased microwave power amplifier, we obtained about 30 W of the output which seems enough for the present measurement. We employed the TM1 10 oscillation mode of microwave cavity which is expected to be stable and keep high Q-values for inserting a coil for NMR measurement.
To obtain a wide microwave frequency range of 8,800 to 9,800 MH2 for resonating frequency of the cavity, we tried several methods. A problem was the lowering the resonating frequency when inserting a silica Dewer tube in the cavity for the temperature dependence measurement. We tried to change the microwave frequency by inserting metal or dielectrics in the cavity and adjusting the position of these material in the cavity, but, these trials were in vain. The final success of the frequency scan was obtained by precisely moving the position of the silica tube in the vertical direction. This operation needs a fine movement of the tube, but we could scan a wide frequency range.
The detection of NMR signals was performed by use of our pulsed NMR spectrometer in which the rf coil was carefully constructed not to lose the Q-value of the cavity.
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