Coupling between Harmonic Vibrations Influences Quantum Beating Signatures in Two-Dimensional Electronic Spectra
Coupling between Harmonic Vibrations Influences Quantum Beating Signatures in Two-Dimensional Electronic Spectra
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DOI：
10.1021/acs.jpcc.1c09432
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发表时间：
2022-01-04
影响因子：
3.7
通讯作者：
Wasielewski，Michael R.
中科院分区：
文献类型：
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作者：
Schultz，Jonathan D.;Kim，Taeyeon;Wasielewski，Michael R.
发射和跟踪波包动力学与二维电子能谱（2DES）提供洞察复杂的相互作用，在光活性材料的相干过程的基础上。随着人们对电子-振动（振动）相互作用如何直接影响超快光物理的兴趣日益浓厚，将2DES结果转化为对分子势能景观有意义的描述的方法必须相应地发展。量子比特图的解释提供了对化学系统内和色团间耦合的直接洞察，经常依赖于解释单个核坐标的物理模型。然而，最近的一些研究表明，由几种不同振动运动产生的波包之间的耦合以有意义的方式影响2DES数据。我们在这些见解的基础上，直接比较了使用单组分和多组分振动哈密顿子的模拟与有机半导体terrylenedi亚胺和ITIC以及生物医学染料亚甲基蓝和尼罗河蓝a的实验2DES结果。我们表明，当模拟中包含低频和高频振动运动时，实验beatmaps和傅立叶功率谱得到了很好的再现。此外，我们证明了谐波波包的相互作用增加了正频重相信号中的量子拍幅，这大大增加了从2DES数据中分离基态和激发态振动相干特征的标准方法的复杂性。这些发现表明，纯谐波振动波包之间的耦合对实验2DES结果有显著和普遍的影响。
Launching and tracking wavepacket dynamics with two-dimensional electronic spectroscopy (2DES) provides insight into the complex interactions that underlie coherent processes within photoactive materials. With the ever-growing interest in how electronic-vibrational (vibronic) interactions direct ultrafast photophysics, methods for translating 2DES results into meaningful descriptions of the molecular potential energy landscape must evolve correspondingly. The interpretation of quantum beatmaps, which provide direct insight into the intra- and interchromophoric couplings within a chemical system, frequently relies on physical models that account for a single nuclear coordinate. However, several recent works suggest that coupling between wavepackets borne from several different vibrational motions affects 2DES data in meaningful ways. We build upon these insights by directly comparing simulations using single- and multicomponent vibronic Hamiltonians against experimental 2DES results from the organic semiconductors terrylenediimide and ITIC, as well as the biomedical dyes methylene blue and Nile blue A. We show that the experimental beatmaps and Fourier power spectra are well-reproduced when both low- and high-frequency vibrational motions are included in the simulation. Moreover, we demonstrate that the interaction of harmonic wavepackets increases quantum beat amplitudes in the positive-frequency rephasing signals, which significantly complicates standard methods for separating ground- and excited-state vibrational coherence signatures from 2DES data. These findings illustrate that coupling between purely harmonic vibrational wavepackets can have significant and prevalent effects on experimental 2DES results.