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

利用重复脉冲磁场，研制了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30T的脉冲磁场。信噪比的大幅度提高是通过信号平均技术实现的。使用单次激发型脉冲场，这一比率比传统的ESR光谱仪提高了至少50倍。最高频率可达3太赫兹，远远高于市售W波段电子自旋共振波谱仪。此外，单位时间内可能的扫描次数所定义的效率比使用超导磁体的ESR光谱仪要大得多。在简单的硬件平均方法下，该系统的典型分辨率为10高斯。采用峰值拾取过程，用软件求平均值，可将分辨率提高到1高斯。对梯形化合物和纳米磁性团簇的微单晶进行了测试实验。在目前的系统中，甚至可以观察到非常弱的禁忌跃迁。本结果导致重复脉冲磁场应用于各种类型的光谱，例如用于固态的拉曼散射或X射线光谱。

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.