Development of optically detected magnetic resonance spectrometer and its application for characterization of π-conjugated polymers

在本研究项目中，我们开发了一种零磁场或低磁场条件下的时间分辨光探测磁共振（ODMR）光谱仪。研制了一种250 MHz ~ 1.5 GHz的宽带可重入腔探头。我们组装了一个具有24个独立通道和10ns分辨率的时序发生器。我们利用时序发生器对微波脉冲进行幅度调制和相位调制，并在接收机上进行相敏检测。采用滤光片选择性波长氙灯作为光源。将数字存储示波器数字化后的相敏检测信号通过通用接口总线（GPIB）传输到计算机，然后进行平均处理。我们成功地研制了时间分辨ODMR光谱仪系统，该系统将微波部分和光学部分连接起来。对π共轭聚合物的模型化合物1,4-二溴二萘（DBN）进行了光学探测电子顺磁共振（ODEPR）和光学探测核磁四极共振（ODNQR）测量。作为初步研究，用^<13>C和^2H固体核磁共振研究了一些具有高区域规整性的五元环π-电子共轭聚合物的固态结构。我们对99%头对头聚（4-甲基噻吩-2,5-二基）（HH-P4MeTz）和99%头对头聚（3-甲基噻吩-2,5-二基）（HT-P3MeTh）进行了^<13>C交叉极化和魔幻角样品纺丝（CPMAS）测量，这两种化合物是通过零价镍配合物的脱卤缩聚合成的。利用二维自旋回波测量和从头算MP2化学屏蔽计算对甲基碳的化学屏蔽张量的主成分进行了分析，结果表明，甲基碳的主扭与分子内甲基旋转高度相关，甲基碳的两种不同信号属于有序相和准有序相。甲基-氘化HH-P4MeTz的变温^2H四极核磁共振测量证实了两相的共存。值得注意的是，即使在侧链较短的聚合物中也观察到准有序相。少

In this research project, we developed a time-resolved optically detected magnetic resonance(ODMR) spectrometer at a zero or low magnetic field condition. A broadband reentrant cavity probe with a range of 250 MHz〜1.5 GHz were built.We have assembled a timing generator with 24 independent channels and 10 ns resolution. We make use of the timing generator for amplitude modulations and phase modulation of microwave pulses, and phase sensitive detection at the receiver. A xenon flash lamp with a selective wave length by optical filter was used as a light source. The phase-sensitive detected signals digitized by a digital storage oscilloscope were transferred to a computer via a general purpose interface bus(GPIB), and then averaged. We succeeded in developing the time resolved ODMR spectrometer system with connecting both the microwave and optical portions. We have made optically detected electron paramagnetic resonance(ODEPR) and optically detected nuclear magnetic quadrupolar resonance( … More ODNQR) measurements of 1,4-dibromonaphthalene (DBN), which is a model compounds to π-conjugated polymers.As a preliminary research, solid-state structure of some five-membered ring π-electron conjugated polymers with high regio-regularity was investigated by the ^<13>C and ^2H solid-state NMR. We performed ^<13>C cross polarization and magic-angle sample spinning (CPMAS) measurements of 99 % head-to-head poly(4-methylthiazole-2,5-diyl) (HH-P4MeTz) and 99 % head-to-head poly(3-methylthiophene-2,5-diyl) (HT-P3MeTh), which were synthesized by dehalogenative polycondensations with zero-valent nickel complexes. An analysis of principal components of chemical shielding tensor for the methyl carbon determined by the two-dimensional spin-echo measurements and ab initio MP2 chemical shielding calculation show that the backbone twist in highly correlated with the intramolecular methyl rotaion and that the two distinctive signals of the methyl carbons are attributed to the ordered and the quasi-ordered phases. Coexistence of the both phases were manifested by variable temperature ^2H quadrupolar NMR meansurements for methyl-deuterated HH-P4MeTz. It is noticeable that the quasi-ordered phase is observed even in polymers with the short side chain. Less