Terahertz dynamics of ionic liquids from a combined dielectric relaxation, terahertz, and optical Kerr effect study: evidence for mesoscopic aggregation
Terahertz dynamics of ionic liquids from a combined dielectric relaxation, terahertz, and optical Kerr effect study: evidence for mesoscopic aggregation
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介电弛豫、太赫兹和光学克尔效应联合研究的离子液体太赫兹动力学：介观聚集的证据
DOI：
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
K. Wynne
中科院分区：
文献类型：
--
作者：
D. Turton;J. Hunger;A. Stoppa;G. Hefter;A. Thoman;M. Walther;R. Buchner;K. Wynne
为了开发室温离子液体（RTIL）作为溶剂的巨大潜力，提供低环境影响和产品选择性，对液体结构，微观动力学的理解，以及相关的宏观性质，如粘度，热导率，离子扩散和溶剂化动力学取决于这些性质的方式，是必不可少的。我们已经测量了1，3-二烷基咪唑基RTIL [emim][BF 4]，[emim][DCA]和[bmim][DCA]的分子间动力学，在25 °C下从低于1 GHz到10 THz，通过超快光学克尔效应（OKE）光谱和介电弛豫光谱（DRS）增强时域太赫兹和远红外FTIR光谱。这种协调一致的方法允许对相对无特征的太赫兹区域进行更详细的分析，其中较高频率的扩散模式与振动和分子间振动强烈重叠。在太赫兹区域中，OKE光谱的信噪比特别高，并且数据显示，比以前检测到的更多的振动模式和分子间振动模式。然而，最有趣的是一个强烈的低频（亚α）弛豫，我们表明这与最近的模拟结果非常一致，这些模拟结果观察到了聚集体或簇产生的介观结构;结构解释了这些液体的异常和不寻常的高粘度。
To exploit the great potential of room-temperature ionic liquids (RTILs) as solvents that offer both low environmental impact and product selectivity, an understanding of the liquid structure, the microscopic dynamics, and the way in which the pertinent macroscopic properties, such as viscosity, thermal conductivity, ionic diffusion, and solvation dynamics depend on these properties, is essential. We have measured the intermolecular dynamics of the 1,3-dialkylimidazoliumbased RTILs [emim][BF4], [emim][DCA], and [bmim][DCA], at 25 °C from below 1 GHz to 10 THz by ultrafast optical Kerr effect (OKE) spectroscopy and dielectric relaxation spectroscopy (DRS) augmented by time-domain terahertz and far-infrared FTIR spectroscopy. This concerted approach allows a more detailed analysis to be made of the relatively featureless terahertz region, where the higher frequency diffusional modes are strongly overlapped with librations and intermolecular vibrations. In the terahertz region, the signal-to-noise ratio of the OKE spectra is particularly high and the data show that there is a greater number of librational and intermolecular vibrational modes than previously detected. Of greatest interest though, is an intense low frequency (sub-alpha) relaxation that we show is in strong accordance with recent simulations that observe mesoscopic structure arising from aggregates or clusters; structure that explains the anomalous and inconveniently-high viscosities of these liquids.
通过光学克尔效应光谱研究氢键液体 N-甲基乙酰胺和水的结构弛豫。
DOI：
10.1063/1.2897432
发表时间：
2008
期刊：
The Journal of chemical physics
影响因子：
--
作者：
Turton DA
通讯作者：
Turton DA
影响因子：
15
作者：
Turton, David A.;Hunger, Johannes;Wynne, Klaas
通讯作者：
Wynne, Klaas