2005 Fiscal Year Final Research Report Summary
Development of pulsed EPR spectrometer with pulsed field gradient
| Project/Area Number |
16550003
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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 | Tohoku University |
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Principal Investigator |
OHBA Yasunori Tokoku University, Institute of Multidisciplinary Research for Advanced Materials, Associate Professor, 多元物質科学研究所, 助教授 (10176985)
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| Project Period (FY) |
2004 – 2005
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| Keywords | pulsed EPR / pulsed magnetic field gradient / two dimensional EPR / double quantum EPR / dielectric resonator / quadruple coil |
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| Research Abstract |
Aiming for applications such as coherence path selection, saturation experiments, and diffusion measurements, at X-band (9.5GHz) pulsed EPR, a pulsed magnetic field gradient system was developed. The pulsed magnetic field system is consists of a pulsed magnetic field driver, a quadruple field gradient coil, a dielectric resonator, a low temperature helium flow cryostat, and photo irradiation system. The driver can produce an electric current pulse of 10 A with 10 ns switching time. A quadruple coil (7 mm φ and 10 mm length) was designed by a numerical calculation of magnetic field inside the coil based on the Viot-Savart's low. The small size of the coil enables one to generate a large magnetic field with fast switching times. The coil can generates field gradient of 100 G/cm at the sample position. An EPR resonator for this application must be small to be placed in the small quadruple coil. To satisfy this condition, a loop-gap resonator (LGR) and a dielectric resonator (DR) were examined. The LGR with single gap and five slits for the introduction of transient magnetic field was made from copper. An experiment showed that the metal wall of LGR attenuates the transient magnetic field inside the resonator to 1/5 with respect to the empty coil. DR was made from CaTiO3 (ε_r=20) to be an appropriate size to place in the coil and to satisfy resonance condition at 9.5 GHz. Because the material is insulator, the pulsed magnetic field can be introduced at the sample position without attenuation. Thus, DR is chosen as the best resonator for the pulsed magnetic field measurements. The designed low temperature cryostat can provide easy coupling adjustment of the microwave signal and sample exchange. An efficient photo irradiation method was also developed with using optical fiber.
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