Herein, the data of the intermolecular vibrations of forty nonaromatic cation based ionic liquids (ILs) at 293 K measured by femtosecond Raman-induced Kerr effect spectroscopy are reported. The low-frequency spectra in the frequency range of 0.3–700 cm⁻¹ were obtained by Fourier transform deconvolution analysis. The line shape of the low-frequency spectra below ~200 cm⁻¹ were discussed on the basis of the ion species. The spectral intensity in nonaromatic cation based ILs was much lower than that in aromatic cation based ILs owing to the absence of the aromatic ring, i.e., the libration of the aromatic species had a strong spectral intensity in the low-frequency region. However, nonaromatic cation based ILs with a flat anion, such as dicyanamide and tricyanomethide, showed stronger spectral intensity because of the libration of the anion. Other unique spectral features were also discussed in the context of the structure of the ion species. Liquid properties, such as density, viscosity, electrical conductivity, and surface tension, were also estimated. On comparing the low-frequency spectra with the bulk liquid properties of the nonaromatic cation based ILs, a mild linear relationship between the first moment of the low-frequency spectra and a bulk parameter comprised of surface tension and density was observed.

中文翻译：

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非芳香族阳离子离子液体的超快动力学：飞秒拉曼诱导的克尔效应光谱研究

在此，报道了通过飞秒拉曼诱导的克尔效应光谱法测量的在293 K下的四十个非芳香族阳离子型离子液体（ILs）的分子间振动数据。通过傅立叶变换反卷积分析获得了0.3–700 cm ^-1频率范围内的低频频谱。低于〜200 cm ^-1的低频频谱的线形根据离子种类进行了讨论。由于不存在芳环，因此基于非芳族阳离子的ILs的光谱强度比基于芳族阳离子的ILs的光谱强度低得多，即芳族物质的释放在低频区域具有很强的光谱强度。但是，由于阴离子的释放，具有平面阴离子的非芳香族阳离子基离子分子（如双氰胺和三氰甲基甲烷）显示出更强的光谱强度。在离子物种结构的背景下，还讨论了其他独特的光谱特征。还估计了液体性质，例如密度，粘度，电导率和表面张力。在比较低频光谱和非芳香族阳离子基离子液体的整体液体性质时，