Charge and electric field fluctuations in aqueous NaCl electrolytes.
Charge and electric field fluctuations in aqueous NaCl electrolytes.
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DOI：
10.1021/jp405578w
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发表时间：
2013-08
期刊：
影响因子：
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通讯作者：
Bernhard Sellner;M. Valiev;S. Kathmann
中科院分区：
文献类型：
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作者：
Bernhard Sellner;M. Valiev;S. Kathmann
晶体发光，在某些盐的结晶过程中长寿命的可见光发射，在200多年前首次被观察到;然而，这种发光的起源仍然没有很好的理解。观察表明，结晶的过程可能不是纯粹的经典，但也涉及到一个重要的电子结构组件。强电场波动可能在这一过程中发挥重要作用，为观察到的电子结构变化提供必要的驱动力。这项工作的主要目的是提供一个基本的了解，在电荷，电势和电场的波动，为浓NaCl水溶液电解质。我们的电荷分析表明，水分子在第一溶剂化壳层的离子作为一个水槽的电子密度起源于Cl（-）。我们发现，水电解质内的电场是非常大的（高达几个V/V），因此可能会改变地面和激发电子状态的凝聚相。此外，我们的研究结果表明，潜在的和场分布在很大程度上是独立的浓度。我们还发现，场分量分布是高斯的离子和非高斯的O和H网站（在实验室的参考系计算），然而，这些非高斯分布很容易通过一个取向平均的非零均值高斯加零均值高斯建模。这些计算和分析提供了第一步了解的幅度和波动的电荷，电势，和字段在水性电解质和这些字段可能发挥什么作用，在驱动电荷重新分配/转移在晶体发光。
Crystalloluminescence, the long-lived emission of visible light during the crystallization of certain salts, was first observed over 200 years ago; however, the origin of this luminescence is still not well understood. The observations suggest that the process of crystallization may not be purely classical but also involves an essential electronic structure component. Strong electric field fluctuations may play an important role in this process by providing the necessary driving force for the observed electronic structure changes. The main objective of this work is to provide a basic understanding of the fluctuations in charge, electric potentials, and electric fields for concentrated aqueous NaCl electrolytes. Our charge analysis reveals that the water molecules in the first solvation shell of the ions serve as a sink for electron density originating on Cl(-). We find that the electric fields inside aqueous electrolytes are extremely large (up to several V/Å) and thus may alter the ground and excited electronic states in the condensed phase. Furthermore, our results show that the potential and field distributions are largely independent of concentration. We also find the field component distributions to be Gaussian for the ions and non-Gaussian for the O and H sites (computed in the lab frame of reference), however, these non-Gaussian distributions are readily modeled via an orientationally averaged nonzero mean Gaussian plus a zero mean Gaussian. These calculations and analyses provide the first steps toward understanding the magnitude and fluctuations of charge, electric potentials, and fields in aqueous electrolytes and what role these fields may play in driving charge redistribution/transfer during crystalloluminescence.