The role of coherences, or coherently excited superposition states, in complex condensed-phase systems has been the topic of intense interest and debate for a number of years. In many cases, coherences have been utilized as spectators of ultrafast dynamics or for identifying couplings between electronic states. In rare cases, they have been found to drive excited state dynamics directly. Interestingly though, the utilization of coherences as a tool for high-detail vibronic spectroscopy has largely been overlooked until recently, despite their encoding of key information regarding molecular structure, electronically sensitive vibrational modes, and intermolecular interactions. Furthermore, their detection in the time domain makes for a highly comprehensive spectroscopic technique wherein the phase and dephasing times are extracted in addition to amplitude and intensity, an element not afforded in analogous frequency domain “steady-state” measurements. However, practical limitations arise in disentangling the large number of coherent signals typically accessed in broadband nonlinear spectroscopic experiments, often complicating assignment of the origin and type of coherences generated.

中文翻译：

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凝聚相干相干光谱：分子结构，环境和相互作用的见解。

多年来，相干或相干激发的叠加态在复杂的凝聚相系统中的作用一直是引起人们广泛关注和争论的话题。在许多情况下，相干性已被用作超快动力学的旁观者或用于识别电子状态之间的耦合。在极少数情况下，已发现它们直接驱动激发态动力学。尽管有趣的是，相干作为高细节振动电子光谱学的一种工具，尽管它们对有关分子结构，电敏感的振动模式和分子间相互作用的关键信息进行了编码，但直到最近仍被广泛忽略。此外，它们在时域中的检测形成了一种高度综合的光谱技术，其中除了幅度和强度外，还提取了相位和相移时间，这是类似频域“稳态”测量中所没有的。然而，在解开通常在宽带非线性光谱实验中获得的大量相干信号时，实际的局限性出现了，这通常会使所产生的相干的来源和类型的分配变得复杂。