Magnetic field effects and the role of spin states in singlet fission
Magnetic field effects and the role of spin states in singlet fission
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DOI：
10.1016/j.cplett.2013.08.036
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发表时间：
2013-10-14
影响因子：
2.8
通讯作者：
Bardeen, Christopher J.
中科院分区：
文献类型：
--
作者：
Burdett, Jonathan J.;Piland, Geoffrey B.;Bardeen, Christopher J.
单线态裂变是一种光物理过程，有望提高太阳能电池的效率。动力学取决于三重态自旋态，并可受外部磁场的影响。在四电子系统中，裂变从初始的单重态转变为三重态的叠加态。四烯晶体延迟荧光中的量子拍提供了这种叠加态的直接证据。拍频取决于晶体相对于磁场的取向，与基于解全自旋哈密顿量的预测一致。根据混合量子动力学模型分析了磁场对动力学的影响。磁场对初始荧光衰减率没有影响，但在三重态对态开始与单重态平衡后会影响荧光衰减。荧光衰变的长时间行为反映了三重态对的结合和分离以及弛豫到不同的自旋态。(C) 2013 Elsevier B.V.版权所有
Singlet fission is a photophysical process that has promise for increasing the efficiency of solar cells. The dynamics depend on triplet spin states and can be influenced by external magnetic fields. In 4-electron systems, fission takes an initial singlet state into a superposition of triplet pair states. Direct evidence for this superposition state is provided by quantum beats in the delayed fluorescence of tetracene crystals. The beat frequencies depend on crystal orientation with respect to the magnetic field, consistent with predictions based on solving the full spin Hamiltonian. Magnetic field effects on the kinetics are analyzed in terms of a hybrid quantum-kinetic model. The magnetic field has no effect on the initial fluorescence decay rate but affects the decay after the triplet pair states begin to equilibrate with the singlets. The long-time behavior of the fluorescence decay reflects association and separation of triplet pairs and relaxation into different spin states. (C) 2013 Elsevier B.V. All rights reserved.