Vibrational Spectrum of an Excited State and Huang-Rhys Factors by Coherent Wave Packets in Time-Resolved Fluorescence Spectroscopy
Vibrational Spectrum of an Excited State and Huang-Rhys Factors by Coherent Wave Packets in Time-Resolved Fluorescence Spectroscopy
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DOI：
10.1002/cphc.201601295
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发表时间：
2017-03-17
期刊：
影响因子：
2.9
通讯作者：
Joo, Taiha
中科院分区：
文献类型：
--
作者：
Lee, Gyeongjin;Kim, Junwoo;Joo, Taiha
利用双光子吸收激发和非共线和频产生的荧光上转换技术，通过时间分辨自发荧光光谱直接测量了分子电子激发态的相干核波包运动，获得了前所未有的时间分辨率。在时间分辨率约为25 fs的条件下，记录了香豆素153在乙醇中振动模的波包运动，波包的振动模可达1600 cm（-1）。测量了13 fs时间分辨率的双色瞬态吸收，证实了这一结果。用量子力学方法计算了基态和激发态之间的振动位移和黄-里斯因子，并与实验结果进行了比较。用密度泛函理论（DFT）和含时DFT计算的HRF与实验结果吻合较好。这种基于荧光的方法提供了一种独特而直接的方式来获得处于电子激发态的分子的振动光谱和HRF，以及激发态的动力学，并且它可能通过HRF提供关于激发态结构的信息。
Coherent nuclear wave packet motions in an electronic excited state of a molecule are measured directly by time-resolved spontaneous fluorescence spectroscopy with an unprecedented time resolution by using two-photon absorption excitation and fluorescence upconversion by noncollinear sum frequency generation. With an estimated time resolution of approximately 25fs, wave packet motions of vibrational modes up to 1600cm(-1) are recorded for coumarin153 in ethanol. Two-color transient absorption at 13fs time resolution are measured to confirm the result. Vibrational displacements between the ground and excited states and Huang-Rhys factors (HRFs) are calculated by quantum mechanical methods and are compared with the experimental results. HRFs calculated by density functional theory (DFT) and time-dependent DFT reproduce the experiment adequately. This fluorescence-based method provides a unique and direct way to obtain the vibrational spectrum of a molecule in an electronic excited state and the HRFs, as well as the dynamics of excited states, and it might provide information on the structure of an excited state through the HRFs.