A discrete interaction model/quantum mechanical method for simulating surface-enhanced Raman spectroscopy in solution
A discrete interaction model/quantum mechanical method for simulating surface-enhanced Raman spectroscopy in solution
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DOI：
10.1063/5.0051256
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发表时间：
2021-06-14
影响因子：
4.4
通讯作者：
Jensen, Lasse
中科院分区：
文献类型：
--
作者：
Becca, Jeffrey C.;Chen, Xing;Jensen, Lasse
由于表面增强拉曼散射（Sers）是相当大的兴趣，在水溶液中的传感应用，溶剂中发挥的作用，光谱必须加以理解。然而，这些努力受到阻碍，由于缺乏模拟方法建模溶剂在Sers。本文基于离散相互作用模型/量子力学方法，提出了一种模拟水溶液中Sers的原子电动力学-量子力学方法。这种方法结合了一个原子电动力学模型的纳米粒子与时间相关的密度泛函理论描述的分子和可极化的嵌入方法的溶剂。溶剂分子和纳米颗粒的显式处理导致需要考虑大量的可极化偶极子。为了降低计算成本，一个简单的截止为基础的方法已经实施，以限制需要处理的偶极子的数量，而不牺牲精度。作为该方法的一个试验，我们研究了溶剂对吡啶在水溶液中纳米颗粒间结合处的Sers的影响。我们发现，溶剂导致增强的Sers由于在吡啶的位置增加的局部场。我们进一步证明了图像场和局部场效应在确定增强和光谱特征方面的重要性。我们的研究结果表明，由于溶剂Sers建模时，描述局部环境的重要性。由AIP Publishing独家授权发布。
Since surface-enhanced Raman scattering (SERS) is of considerable interest for sensing applications in aqueous solution, the role that solvent plays in the spectroscopy must be understood. However, these efforts are hindered due to a lack of simulation approaches for modeling solvent in SERS. In this work, we present an atomistic electrodynamics-quantum mechanical method to simulate SERS in aqueous solution based on the discrete interaction model/quantum mechanical method. This method combines an atomistic electrodynamics model of the nanoparticle with a time-dependent density functional theory description of the molecule and a polarizable embedding method for the solvent. The explicit treatment of solvent molecules and nanoparticles results in a large number of polarizable dipoles that need to be considered. To reduce the computational cost, a simple cut-off based approach has been implemented to limit the number of dipoles that need to be treated without sacrificing accuracy. As a test of this method, we have studied how solvent affects the SERS of pyridine in the junction between two nanoparticles in aqueous solution. We find that the solvent leads to an enhanced SERS due to an increased local field at the position of the pyridine. We further demonstrate the importance of both image field and local field effects in determining the enhancements and the spectral signatures. Our results show the importance of describing the local environment due to the solvent molecules when modeling SERS. Published under an exclusive license by AIP Publishing.