Regulation of Photochemical Reactions by Laser and Magnetic Field

本项目的目的是开发利用激光和磁场控制光化学反应的新技术。(1)激光强度：266 nm激光激发A，A ′-二氯-邻二甲苯导致邻二甲苯的形成。从其激光功率的依赖性，它表明，邻二甲苯产生的单光子和双光子过程。(2)磁场：从磁场对链状单重态和三重态双自由基的影响分析，阐明了磁场作用的机理。(3)激光和磁场：在双发色团链状双重氮分子的瞬态吸收光谱中，只有在强激光激发下才能观察到磁场效应。在强激发下，通过双光子过程产生链状双卡宾和双自由基。外加磁场对双自由基的三线态-单线态跃迁有影响，从而阐明了激光和磁场控制反应的机理。

The aim of this project is to develop the novel technique for controlling photochemical reactions by laser and magnetic field.(1) Laser Intensity: The 266 nm laser excitation of &A, &A'-dichloro-o-xylene results in the formation of o-xylylene. From its laser power dependence, it is shown that o-xylylene is generated both one- and two-photon process. (2) Magnetic Field: From the analysis of the magnetic field effect upon the chainlinked singlet and triplet biradicals, its mechanism are precisely clarified. (3) Laser and Magnetic field: In the transient absorption spectra of a bichromophoric chain-linked bisdiazo molecule, magnetic field effect is observed only when the spectra are measured under the intense laser excitation. Upon the intense excitation, a chain-linked biscarbene and a biradical is generated via two-photon process. An external magnetic field affects triplet-singlet intersystem crossing of the biradical generated.In conclusion, the mechanisms of reaction control by laser and magnetic field are clarified.