Ciardi Gustavo, Berger Arian, Hamm Peter, Shalit Andrey
Department of Chemistry , University of Zurich , Winterthurerstrasse 190 , CH-8057 Zurich , Switzerland.
J Phys Chem Lett. 2019 Aug 1;10(15):4463-4468. doi: 10.1021/acs.jpclett.9b01528. Epub 2019 Jul 24.
Hybrid two-dimensional (2D) Raman-terahertz spectroscopy with the Raman-terahertz-terahertz (RTT) pulse sequence is used to explore the ultrafast intra- and intermolecular degrees of freedom of liquid bromoform (CHBr) in the frequency range of 1-8 THz. Cross peaks observed in these 2D spectra are assigned to the coupling between the narrow intramolecular modes of the molecules and the much broader intermolecular degrees of freedom of the liquid. This assignment is based on the frequency position of the cross peaks; however, it is shown that these frequency positions can be deduced accurately only when properly taking into account the convolution of the molecular response with the instrument response function of the experimental setup, the latter of which distorts the 2D spectra considerably. The assignment is supported by additional experiments on diiodomethane (CHI), which has only one intramolecular mode in the frequency range of the experiment, and hence excludes the possibility of intramolecular couplings.
采用拉曼-太赫兹-太赫兹（RTT）脉冲序列的混合二维（2D）拉曼-太赫兹光谱，用于在1-8太赫兹频率范围内探索液态溴仿（CHBr₃）的超快分子内和分子间自由度。在这些二维光谱中观察到的交叉峰归因于分子的窄分子内模式与液体中更宽的分子间自由度之间的耦合。这种归属基于交叉峰的频率位置；然而，结果表明，只有在适当考虑分子响应与实验装置的仪器响应函数的卷积时，才能准确推导出这些频率位置，后者会使二维光谱产生相当大的畸变。对二碘甲烷（CH₂I₂）的额外实验支持了这一归属，二碘甲烷在实验频率范围内只有一种分子内模式，因此排除了分子内耦合的可能性。
