Quantum Coherence in Ultrafast Photo-driven Charge Separation
Quantum Coherence in Ultrafast Photo-driven Charge Separation
复制标题
超快光驱动电荷分离中的量子相干性
DOI：
10.1039/c8fd00218e
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发表时间：
2019
影响因子：
3.4
通讯作者：
Wasielewski, Michael R
中科院分区：
文献类型：
--
作者：
Phelan, Brian T;Schultz, Jonathan;Zhang, Jinyuan;Huang, Guan-Jhih;Young, Ryan Michael;Wasielewski, Michael R
相干相互作用在光驱动过程中普遍存在，从光合能量转移到超交换介导的电子转移，导致大量研究旨在识别和理解这些相互作用。这种兴趣的一个关键动机是由于量子干涉而连贯地穿过多个路径所产生的非统计标度定律。为此，我们采用超快瞬态吸收光谱来测量两个供体-受体分子系统中的电子转移，该系统包括对-(9-蒽基)-N,N-二甲基苯胺发色团/电子供体和一个或两个等效的萘-1,8:4,5-双(二甲酰亚胺)电子受体在环境温度和低温下的电子转移。两个受体化合物在室温下显示出 2.1 ± 0.2 速率增强的统计因子，在低温下显示出 2.6 ± 0.2 速率增强的非统计因子，表明两个受体与供体和浴模式之间存在相关的相互作用。比较电荷复合率表明电子在低温下在两个受体上离域，但在室温下集中在单个受体上。这些结果强调了保护系统免受浴波动影响以保持并最终利用相干相互作用的重要性。
Coherent interactions are prevalent in photodriven processes, ranging from photosynthetic energy transfer to superexchange-mediated electron transfer, resulting in numerous studies aimed towards identifying and understanding these interactions. A key motivator of this interest is the non-statistical scaling laws that result from coherently traversing multiple pathways due to quantum interference. To that end, we employed ultrafast transient absorption spectroscopy to measure electron transfer in two donor–acceptor molecular systems comprising a p-(9-anthryl)-N,N-dimethylaniline chromophore/electron donor and either one or two equivalent naphthalene-1,8:4,5-bis(dicarboximide) electron acceptors at both ambient and cryogenic temperatures. The two-acceptor compound shows a statistical factor of 2.1 ± 0.2 rate enhancement at room temperature and a non-statistical factor of 2.6 ± 0.2 rate enhancement at cryogenic temperatures, suggesting correlated interactions between the two acceptors with the donor and with the bath modes. Comparing the charge recombination rates indicates that the electron is delocalized over both acceptors at low temperature but localized on a single acceptor at room temperature. These results highlight the importance of shielding the system from bath fluctuations to preserve and ultimately exploit the coherent interactions.