Coherent two-dimensional terahertz-terahertz-Raman spectroscopy
Coherent two-dimensional terahertz-terahertz-Raman spectroscopy
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DOI：
10.1073/pnas.1605631113
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发表时间：
2016-06-21
影响因子：
11.1
通讯作者：
Blake, Geoffrey A.
中科院分区：
文献类型：
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作者：
Finneran, Ian A.;Welsch, Ralph;Blake, Geoffrey A.
我们提出了2D太赫兹-太赫兹-拉曼（2D TTR）光谱，第一种技术，据我们所知，询问液体与多个脉冲的太赫兹（THz）光。这种混合方法隔离了各向同性介质中的非线性特征，并且对在液相化学中起核心作用的热激活THz模式的耦合和非谐性敏感。具体来说，通过改变两个强太赫兹脉冲之间的定时，我们控制液体中分子的取向排列，并非线性地激发振动相干。溴仿（CHBr 3），四氯化碳（CCl 4），和二溴二氯甲烷（CBr 2Cl 2）的实验和模拟的二维TTR光谱的比较显示以前未观察到的非对角非谐耦合热填充振动模式之间。
We present 2D terahertz-terahertz-Raman (2D TTR) spectroscopy, the first technique, to our knowledge, to interrogate a liquid with multiple pulses of terahertz (THz) light. This hybrid approach isolates nonlinear signatures in isotropic media, and is sensitive to the coupling and anharmonicity of thermally activated THz modes that play a central role in liquid-phase chemistry. Specifically, by varying the timing between two intense THz pulses, we control the orientational alignment of molecules in a liquid, and non-linearly excite vibrational coherences. A comparison of experimental and simulated 2D TTR spectra of bromoform (CHBr3), carbon tetrachloride (CCl4), and dibromodichloromethane (CBr2Cl2) shows previously unobserved off-diagonal anharmonic coupling between thermally populated vibrational modes.