Ultrafast Dynamics in 1-Butyl-3-methylimidazolium-Based Ionic Liquids : A Femtosecond Raman-Induced Kerr Effect Spectroscopic Study
Ultrafast Dynamics in 1-Butyl-3-methylimidazolium-Based Ionic Liquids : A Femtosecond Raman-Induced Kerr Effect Spectroscopic Study
复制标题
1-丁基-3-甲基咪唑基离子液体中的超快动力学：飞秒拉曼诱导克尔效应光谱研究
DOI：
10.1021/jp200370f
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发表时间：
2011
影响因子：
3.3
通讯作者：
Hideaki Shirota
中科院分区：
文献类型：
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作者：
Hiroki Fukazawa;Tateki Ishida;Hideaki Shirota
我们研究了1-丁基-3-甲基咪唑离子液体的超快动力学，该离子液体具有两个系列阴离子，(1)氰基取代阴离子(硫氰酸盐[SCN]−，二氰胺[N（CN)2]−，三氰胺[C(CN)3]−）和(2)三氟甲基磺酰基取代阴离子（三氟甲磺酸盐[OTf]−，二（三氟甲基磺酰基）酰胺[NTf2]−，三（三氟甲基磺酰基）甲基[CTf3]−）。这是通过飞秒拉曼诱导克尔效应光谱完成的。从离子液体的傅里叶变换Kerr谱中可以看出，由于正离子和阴离子的平面结构，1-丁基-3-甲基咪唑三氰胺的低频谱与其他氰基取代阴离子相比有低频移位。三氟甲基磺酰基取代阴离子离子液体在大约20 cm−1处的低频相对振幅与整个广谱相比变得更大，其量级为[OTf]−< [NTf2]−≈[CTf3]−。这个振动带可以归因于阴离子的振动运动和/或平动和重定向运动的耦合。
We investigated the ultrafast dynamics in 1-butyl-3-methylimidazolium-based ionic liquids with two series of anions, (1) cyano-group substituted anions (thiocyanate [SCN]−, dicyanamide [N(CN)2]−, and tricyanomethide [C(CN)3]−) and (2) trifluoromethylsulfonyl-group substituted anions (trifluoromethanesulfonate [OTf]−, bis(trifluoromethylsulfonyl)amide [NTf2]−, and tris(trifluoromethylsulfonyl)methide [CTf3]−). This was done by femtosecond Raman-induced Kerr effect spectroscopy. From the Fourier transform Kerr spectra of the ionic liquids, the low-frequency spectrum of 1-butyl-3-methylimidazolium tricyanomethide shows a low-frequency shift compared to the ILs with the other cyano-group substituted anions due to the planar structures of the cation and the anion. The relative amplitude of the low-frequency band at approximately 20 cm−1compared to the entire broad spectrum for the ionic liquids with trifluoromethylsulfonyl-group substituted anions becomes larger with the order [OTf]−< [NTf2]−≈ [CTf3]−. This vibrational band can be attributed to the librational motion of anions and/or the coupling of the translational and reorientational motions.