Solvation dynamics in acetonitrile: A study incorporating solute electronic response and nuclear relaxation
Solvation dynamics in acetonitrile: A study incorporating solute electronic response and nuclear relaxation
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DOI：
10.1021/jp0456032
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发表时间：
2005-03-03
影响因子：
3.3
通讯作者：
Tomasi, J
中科院分区：
文献类型：
--
作者：
Ingrosso, F;Ladanyi, BM;Tomasi, J
在乙腈等极性溶剂中，极性溶质在电子激发后的溶剂重组过程主要与溶质-溶剂静电相互作用的时间演化有关。现代激光技术具有足够的时间分辨率来实时跟踪这种衰变，提供由理论和模型确认和解释的信息。我们在此提出一项研究，旨在从溶质和溶剂的角度研究乙腈中大尺寸发色团香豆素 153 (C153) 的垂直 So --> S 激发后发生的过程中涉及的不同步骤。为此，我们对存在溶剂的 C153 的可极化连续介质模型 (PCM) 和经典分子动力学 (MD) 模拟（平衡和非平衡）中的溶质性质进行了精确的量子力学计算。允许改变溶质的几何形状，以便研究内部运动在依赖时间的溶剂化过程中的作用。从模拟数据中获得了溶剂响应函数并与实验进行了比较，而溶剂化响应的平衡和非平衡MD结果之间的比较证实了C153-乙腈体系中线性响应近似的有效性。 MD 轨迹还用于监测溶剂化壳层的结构并确定其响应溶质部分电荷变化的变化。
The solvent reorganization process after electronic excitation of a polar solute in a polar solvent such as acetonitrile is related mainly to the time evolution of the solute-solvent electrostatic interaction. Modern laser-based techniques have sufficient time resolution to follow this decay in real time, providing information to be confirmed and interpreted by theories and models. We present here a study aimed at the investigation of the different steps involved in the process taking place after a vertical So --> S, excitation of a large size chromophore, coumarin 153 (C153), in acetonitrile, from both the solute and the solvent points of view. To do this, we use accurate quantum mechanical calculations for the solute properties within the polarizable continuum model (PCM) and classical molecular dynamics (MD) simulations, both equilibrium and nonequilibrium, for C153 in the presence of the solvent. The geometry of the solute is allowed to change in order to study the role of internal motions in the time-dependent solvation process. The solvent response function has been obtained from the simulation data and compared to experiment, while the comparison between equilibrium and nonequilibrium MD results for the solvation response confirms the validity of the linear response approximation in the C153-acetonitrile system. The MD trajectories have also been used to monitor the structure of the solvation shell and to determine its change in response to the change in the solute partial charges.