Two-dimensional electronic spectroscopy of molecular excitons.
Two-dimensional electronic spectroscopy of molecular excitons.
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分子激子的二维电子能谱。
DOI：
10.1021/ar800282e
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发表时间：
2009
影响因子：
18.3
通讯作者：
H. Kauffmann
中科院分区：
文献类型：
--
作者：
F. Milota;J. Sperling;A. Nemeth;T. Mančal;H. Kauffmann
通过探索分子对脉冲电磁场序列的非线性响应，对分子系统的核、电子结构和动力学的理解有了很大的进步。能够控制激发脉冲的各种自由度--例如持续时间、顺序、频率、偏振和形状--导致了各种时间分辨光谱方法。研究人员使用的各种技术通常按其维度进行分类，维度指的是诱导信号的脉冲场之间独立可变的时间延迟的数量。尽管电子跃迁的皮秒和飞秒时间分辨光谱已经成熟，但直到最近，研究人员才能够在可见频率范围内执行二维电子光谱(2D-ES)，并将在不同时间间隔内演变的跃迁频率关联起来。二维相关图及其时间演变允许人们访问在其他一维非线性方法中没有直接暴露的光谱信息。在这篇文章中，我们总结了我们对一系列日益复杂的分子生色团的研究。我们研究非相互作用的染料分子，典型染料分子的单体-二聚体平衡，最后是电子耦合吸收体的超分子组装。通过跟踪振动信号调制，区分谱线展宽机制，分析明显不同的驰豫动力学，确定电子耦合强度，以及直接跟踪激发能量转移路径，我们说明了二维电子光谱如何成像构成特定系统光学响应的物理现象。虽然2D-ES远不是一种“交钥匙”方法，但我们预计，实验进展和仪器的潜在商业化将使2D-ES能够为更广泛的科学受众所接受，类似于多维核磁共振和2D-IR的发展。
Understanding of the nuclear and electronic structure and dynamics of molecular systems has advanced considerably through probing the nonlinear response of molecules to sequences of pulsed electromagnetic fields. The ability to control various degrees of freedom of the excitation pulses-such as duration, sequence, frequency, polarization, and shape-has led to a variety of time-resolved spectroscopic methods. The various techniques that researchers use are commonly classified by their dimensionality, which refers to the number of independently variable time delays between the pulsed fields that induce the signal. Though pico- and femtosecond time-resolved spectroscopies of electronic transitions have come of age, only recently have researchers been able to perform two-dimensional electronic spectroscopy (2D-ES) in the visible frequency regime and correlate transition frequencies that evolve in different time intervals. The two-dimensional correlation plots and their temporal evolution allow one to access spectral information that is not exposed directly in other one-dimensional nonlinear methods. In this Account, we summarize our studies of a series of increasingly complex molecular chromophores. We examine noninteracting dye molecules, a monomer-dimer equilibrium of a prototypical dye molecule, and finally a supramolecular assembly of electronically coupled absorbers. By tracing vibronic signal modulations, differentiating line-broadening mechanisms, analyzing distinctly different relaxation dynamics, determining electronic coupling strengths, and directly following excitation energy transfer pathways, we illustrate how two-dimensional electronic spectroscopy can image physical phenomena that underlie the optical response of a particular system. Although 2D-ES is far from being a "turn-key" method, we expect that experimental progress and potential commercialization of instrumentation will make 2D-ES accessible to a much broader scientific audience, analogous to the development of multidimensional NMR and 2D-IR.