Development of high precision THz-ESR system by using repealing pulsed magnetic fields

利用重复脉冲磁场，研制了一套高精度太赫兹电子自旋共振系统。该系统能够每两秒产生高达30 T的脉冲磁场。通过信号平均技术，大大提高了信噪比。通过使用单次激发型脉冲场，该比率变得比常规ESR谱仪高至少50倍。最高频率可达3THz，远高于商用W波段ESR谱仪。此外，由单位时间内可能的扫描次数定义的效率远大于使用超导磁体的ESR谱仪。在简单的硬件平均方法中，本系统的典型分辨率为10高斯。采用峰值拾取法，用软件平均，可将分辨率提高到1高斯。对梯形化合物和纳米磁性团簇微单晶进行了测试实验。即使是很弱的禁戒跃迁也能在本系统中观察到。目前的结果导致应用程序的重复脉冲磁场的各种类型的光谱，如拉曼散射或X射线光谱的固态。

A high precision terahertz ESR system has been developed by using a repeating pulsed magnetic field. The system is capable of generating pulsed magnetic fields up to 30 T every two seconds. The drastic improvement of signal to noise ratio is achieved by the signal averaging technique. The ratio becomes at least 50 times higher than that of the conventional ESR spectrometer by using a single shot type pulse field. The maximum frequency up to 3 THz can be used and it is extremely higher than that of the commercial W-band ESR spectrometer. Moreover, the efficiency defined by the possible number of scans par unit time is much larger than that of ESR spectrometer using superconducting magnets. The typical resolution of the present system is 10 gauss in simple hardware averaging method. The resolution ca be improved to 1 gauss by using a software averaging by suing a peak picking process. Test experiments have been made on a ladder compound and a micro single crystal of nano-magnetic cluster. Even a very weak forbidden transition can be observed by present system. The present result leads to the application of a repeating pulsed magnetic field for various types of spectroscopy such as Raman scattering or X-ray spectroscopy for solid state.