Investigation of the effects of microwave electromagnetic field on the reaction dynamics of radical ion pairs

微波电磁场对自由基离子对反应动力学影响的研究

• 批准号: 15550022
• 负责人: SAKAGUCHI Yoshio
• 金额: $ 2.43万
• 依托单位: RIKEN (The Institute of Physical and Chemical Research)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15550022/
• 关键词: microwave irradiation; radical ion pair; rectangular cavity; Electric-mode; Magnetic-mode; electron transfer reaction; RYDMR; OLED materials; 光化学反応; 電子スピン共鳴

The reaction dynamics of radical pair is affected by the irradiation of microwave which can induce the electron spin resonance of the component radicals. This is due to the effect of magnetic component of microwave. On the other hand, the effect of electric field to materials is generally much larger than that of magnetic field. Therefore, the microwave irradiation to the radical ion pair may induce both of the effects of electric and magnetic components of electromagnetic wave. This is also an example of the chemical effect of electromagnetic field, which is now occupying the public interest. To investigate the independent contribution of electric and magnetic component to the reaction, we developed a dual mode cavity which can apply each of the components to samples. For the photoreaction of 2-methyl-1,4-naphthoquinone in sodium dodecylsulfate micellar solution, forming a neutral (changeless) radical pair, we reconfirmed the contribution of the magnetic component with the dual cavity … More . At the same condition, we could not find significant effect of the electric component. For the photoreaction of 10-methylphenothiazine with 1,4-dicyanobenzene, forming a radical ion pair, we found 〜2% increase of the retardation of the disappearance of escaped radical ions at the irradiation of the microwave pulse in a kW range power. This effect was independent of the magnetic field, excluding the possibility of electron spin resonance.In order to generate a radical ion pair without initial spin correlation, we investigated the emission process of the organic electroluminescence materials(OLED). We found a clear magnetic field effect on the emission intensify of these fluorescent EL materials. The analysis of this dependence revealed that the main origin of this fluorescence of is not the direct emission due to the recombination of singlet radical ion pair but the delayed fluorescence due to the collision of triplet excitons formed in the recombination of triplet radical ion pair at high operating voltages. The irradiation of resonant microwave reduced the emission intensity, which shows the contribution of magnetic component to the emission process. Less

微波辐照能引起自由基对的电子自旋共振，从而影响自由基对的反应动力学。这是由于微波的磁成分的影响。另一方面，电场对材料的影响一般比磁场大得多。因此，微波辐照自由基离子对可以同时引起电磁波的电磁分量和电磁分量的效应。这也是电磁场化学效应的一个例子，现在正占据着公众的兴趣。为了研究电磁分量对反应的独立贡献，我们开发了一个双模腔，它可以将每个分量施加到样品上。对于2-甲基-1，4-萘醌在十二烷基硫酸钠胶束溶液中形成中性（不变）自由基对的光反应，我们再次证实了双腔中磁性组分的贡献 ...更多信息 .在相同条件下，我们没有发现电成分的显著影响。对于10-甲基吩噻嗪与1，4-二氰基苯的光反应，形成自由基离子对，我们发现在kW范围功率的微波脉冲照射下，逃逸自由基离子消失的延迟增加了1.2%。这种效应不受磁场的影响，排除了电子自旋共振的可能性。为了产生一个没有初始自旋关联的自由基离子对，我们研究了有机电致发光材料（OLED）的发光过程。我们发现磁场对这些荧光EL材料的发光强度有明显的影响。对这种依赖关系的分析表明，这种荧光的主要来源不是由于单重态自由基离子对的复合而产生的直接发射，而是由于在高工作电压下三重态自由基离子对的复合中形成的三重态激子的碰撞而产生的延迟荧光。共振微波的辐照使发射强度降低，说明了磁成分对发射过程的贡献。少