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

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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