Ultrafast solvation response in room temperature ionic liquids: possible origin and importance of the collective and the nearest neighbour solvent modes.
Ultrafast solvation response in room temperature ionic liquids: possible origin and importance of the collective and the nearest neighbour solvent modes.
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室温离子液体中的超快溶剂化响应：集体和最近邻溶剂模式的可能起源和重要性。
DOI：
10.1063/1.4752425
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发表时间：
2012
期刊：
影响因子：
--
通讯作者：
R. Biswas
中科院分区：
文献类型：
--
作者：
Snehasis Daschakraborty;R. Biswas
最近的三脉冲光子回波峰移（3 PEPS）测量[M. Muramatsu，Y. Nagasawa和H. Miyasaka，J.Phys.Chem.A 115，3886（2011）]与几种室温离子液体（RTIL）的反应已经揭示了多指数动力学，对于咪唑钥和鳞RTIL两者，具有在20 < τ（1）scinfs < 250范围内的超快溶剂化时间尺度。这是惊人的两个原因：（i）时间尺度比动态斯托克斯位移（DSS）实验报告的要快得多[S。阿尔占采夫Jin，G. A.贝克，和M。Maroncelli，J. Phys. Chem. B 111，4978（2007）]和（ii）首次报道了磷鎓离子液体中的亚百飞秒溶剂化响应。在这里，我们提出了一种基于模式耦合理论的计算，其中3 PEPS测量中的这种超快溶剂化已被视为源于最近邻溶质-溶剂相互作用。考虑最近邻溶质-溶剂非偶极相互作用的Lennard-Jones相互作用导致双相动力学，其预测的超快时间常数在100-250 fs范围内，随后是与3 PEPS测量报告的类似的较慢的时间常数。此外，计算出的快时间常数和振幅与计算机模拟结果基本一致。不同的微观机制的超快溶剂化反应测量的3 PEPS和DSS实验已提出和集体和最近邻溶剂模式的相对贡献进行了研究。探讨了单粒子旋转与超快极性溶剂化的关系。我们的分析表明，3 PEPS和DSS的实验可能是敏感的激光激发的染料在给定的离子液体中的总溶剂化能弛豫的不同组件。也有一些预测，可以通过适当的实验重新检查。
Recent three-pulse photon echo peak shift (3PEPS) measurements [M. Muramatsu, Y. Nagasawa, and H. Miyasaka, J. Phys. Chem. A 115, 3886 (2011)] with several room temperature ionic liquids (RTILs) have revealed multi-exponential dynamics with ultrafast solvation timescale in the range, 20 < τ(1)∕fs < 250, for both imidazolium and phosphonium RTILs. This is striking for two reasons: (i) the timescale is much faster than those reported by the dynamic Stokes shift (DSS) experiments [S. Arzhantsev, H. Jin, G. A. Baker, and M. Maroncelli, J. Phys. Chem. B 111, 4978 (2007)] and (ii) sub-hundered femtosecond solvation response in phosphonium ionic liquids is reported for the first time. Here, we present a mode coupling theory based calculation where such ultrafast solvation in 3PEPS measurements has been visualized to originate from the nearest neighbour solute-solvent interaction. Consideration of Lennard-Jones interaction for the nearest neighbour solute-solvent non-dipolar interaction leads to biphasic dynamics with a predicted ultrafast time constant in the ∼100-250 fs range, followed by a slower one similar to that reported by the 3PEPS measurements. In addition, the calculated fast time constants and amplitudes are found to be in general agreement with those from computer simulations. Different microscopic mechanisms for ultrafast solvation response measured by the 3PEPS and DSS experiments have been proposed and relative contributions of the collective and nearest neighbour solvent modes investigated. Relation between the single particle rotation and ultrafast polar solvation in these RTILs has been explored. Our analyses suggest 3PEPS and DSS experiments are probably sensitive to different components of the total solvation energy relaxation of a laser-excited dye in a given ionic liquid. Several predictions have also been made, which may be re-examined via suitable experiments.
影响因子：
15
作者：
Turton, David A.;Hunger, Johannes;Wynne, Klaas
通讯作者：
Wynne, Klaas