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Development of pulsed EPR spectrometer with pulsed field gradient

脉冲场梯度脉冲EPR光谱仪的研制

基本信息

批准号：
16550003
负责人：
OHBA Yasunori
金额：
$ 2.37万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16550003/
关键词：
pulsed EPR pulsed magnetic field gradient two dimensional EPR double quantum EPR dielectric resonator quadruple coil パルス電子スピン共鳴位相操作電子スピン共鳴

项目摘要

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.

针对x波段（9.5GHz）脉冲EPR的相干路径选择、饱和实验和扩散测量等应用，研制了脉冲磁场梯度系统。脉冲磁场系统由脉冲磁场驱动器、四倍场梯度线圈、介电谐振器、低温氦流低温恒温器和光辐照系统组成。该驱动器可在10ns的开关时间内产生10a的电流脉冲。根据维奥-萨瓦下限，通过对线圈内磁场的数值计算，设计了直径为7mm、长度为10mm的四重线圈。线圈的小尺寸使人们能够产生一个大的磁场和快速的开关时间。该线圈在样品位置可产生100g /cm的场梯度。用于这种应用的EPR谐振器必须很小才能放置在小的四重线圈中。为了满足这一条件，对环隙谐振器（LGR）和介电谐振器（DR）进行了研究。以铜为材料，制作了单隙和5隙引入瞬态磁场的LGR。实验表明，LGR的金属壁使谐振腔内的瞬态磁场衰减为空线圈的1/5。DR由CaTiO3 （ε_r=20）制成，尺寸合适，放置在线圈中，满足9.5 GHz的谐振条件。由于材料是绝缘体，脉冲磁场可以在样品位置引入而不衰减。因此，选择DR作为脉冲磁场测量的最佳谐振器。所设计的低温恒温器可以方便地对微波信号和样品交换进行耦合调节。利用光纤，开发了一种高效的光照射方法。