Coherent vibrational oscillations in femtosecond transient-absorption spectra have been interpreted since the 1990s using a model based on Gaussian wavepacket dynamics. The oscillations are often studied using probe-wavelength dependent plots of the oscillation amplitude and phase that are known as vibrational coherence spectra. Here we show that restricting the basis of the wavepacket to a small number of eigenstates clarifies several features in vibrational coherence spectra. Improving the understanding of vibrational coherence signatures will help distinguish them from signatures of electronic coherence that arise from measurements of strongly coupled excitonic states in molecular aggregates and light-harvesting proteins.

自1990年代以来，飞秒瞬态吸收光谱中的相干振动振荡已经使用基于高斯波包动力学的模型进行了解释。通常使用被称为振动相干谱的振动幅度和相位的探针波长相关图来研究振动。在这里，我们表明将波包的基础限制为少量的本征态可以阐明振动相干谱中的几个特征。增进对振动相干标记的理解将有助于将它们与电子相干标记区分开来，电子相干标记来自分子聚集体和光捕获蛋白中强耦合激子态的测量。