Development of Accurate Measuring Methods of Spin Susceptibility

电子自旋共振(ESR)方法已被证明是检测和鉴定含有不成对电子的化学物种的最好方法，但该方法不适合于化学物种的定量分析。为了保持它的实用性和发展它的定量特征，我们试图用频谱分析仪代替目前使用的相敏检测方法，或用电磁喇叭和三片谐振器代替谐振腔等设计来研制可伸缩的ESR波谱仪。在本研究项目中，我们研究了1)通过在微波频谱分析仪(微波边带ESR)上观察载波微波的第一边带来直接检测ESR信号，2)通过超外差电路(IF边带ESR)从微波频率下变频的中频第一边带获得信号，以及3)使用高频可编程频谱分析仪对微波零差检测(零差边带ESR)后100 kHz的调制频率的信号进行检测。方法1)和2)已经表明，检测到的ESR信号的线形是吸收的，而不是衍生的。因此，这些方法很容易用来估计样品的自旋数(自旋磁化率)。尤其是后一种方法对信号的检测非常敏感。另一方面，方法3)表明线形是导数的，分析谱可用于高阶线形分析。第三种方法对于确定被测ESR信号的g值超精细耦合常数和线宽是非常有用的。基于这些检测方法的特点，对生物重要金属的电子结构和功能进行了研究。研究了络合物及其反应中间体。

Electron spin resonamce(ESR) method has been proved to be best techinique for the detection and identification of chemical species having unpaired elctrons, but this method is not proper for the quantitative analysis of the chemical species. In order to maintain its utilities and develop its quantitative features, we have tried to develop altenative ESR spectrometers by using spectrum analyzers insteas of phase sensitive detection method used so far, or by using sell designs such as electromagnetic horns and triplate resonators instead of the resonant cavity. In this research project we have examined 1) directly to detect the ESR signals by observing 1st sideband of the carrier mictowave on microwave spectrum analyzer (microwave sifeband ESR), 2) to obsarve the signals from the 1st sideband of the intermediate frequency down-converted from the mictowave frequency through a superrheterodyne circuit (IF sideband ESR), and 3) to detect the signals on modulation frequency of 100 kHz after homodyne detection of the mictowave (homodyne sideband ESR), by using a HF programmable spectrum analyzer. Methods 1) and 2) have shown that the line-shape of the detected ESR signals is absorptive rather than derivative. Therefore, these methods are easily applicable to estimate the spin numbers of the samples (spin susceptibility). Especially the latter method has been very sensitive for the detection of the signals. On the other hand, Method 3) has shown that the line shape is derivative and analyzer spectrum can be sarved for the higher-order line-shape analysis. The third method has been proved to be very useful to determine g-value hyperfine coupling constants and line-width of the ESR signals detected. Based on such chatacteristics of the detecting methods, the electronic structure and functions of biologically important metal. complexes and their reaction intermediates have been investigated.