Computer prediction of second harmonic generation at interfaces: NaCl aqueous solution in contact with (101) quartz surfaces

IF 5.2 2区化学 Q2 CHEMISTRY, PHYSICAL

Journal of Molecular Liquids Pub Date : 2025-09-25 DOI:10.1016/j.molliq.2025.128539

Nijat Shukurov , Antoine Djeukeng Momo , Zdeněk Futera , Bingxin Chu , Arianna Marchioro , Milan Předota

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引用次数: 0

Abstract

We present a computational approach for processing classical molecular dynamics (CMD) computer simulations of liquids at solid/liquid interfaces to determine the second-order susceptibility

χ^{(2)}

from the hyperpolarizability

β

of individual water molecules parameterized by quantum calculations. We apply the method to microscopically flat surfaces, but the results can also be applied to scattering from spherical particles (second-harmonic scattering, SHS) in colloidal dispersions. Our

χ^{(2)}

values, calculated from molecular trajectories of aqueous NaCl solutions in contact with (101) quartz surfaces, demonstrate the effect of the surface charge density (0 to

- 0.12

C/m²) and salt concentration (0 to 0.8 M) on the second-order nonlinear response. Moreover, we decompose the total signal into contributions from layers at different distances from the interface, allowing us to distinguish the surface-specific contribution from that of the diffuse layer. Analysis of axial profiles of structural (density, dipolar orientation) and electrostatic (charge density, electric field, electric potential) properties allows us to link them with the optical response. The method can also be applied to other solvents and studies of the impact of different types of dissolved ions and molecules on the non-resonant SH signals.

查看原文本刊更多论文

界面二次谐波产生的计算机预测：NaCl水溶液与（101）石英表面接触

我们提出了一种计算方法，用于处理固体/液体界面液体的经典分子动力学（CMD）计算机模拟，以确定由量子计算参数化的单个水分子的超极化率β的二阶磁化率χ(2)。我们将该方法应用于微观平面，但结果也可以应用于胶体分散体中球形颗粒的散射（二次谐波散射，SHS）。我们的χ(2)值是根据接触（101）石英表面的NaCl水溶液的分子轨迹计算得出的，表明表面电荷密度（0 ~ - 0.12 C/m2）和盐浓度（0 ~ 0.8 M）对二阶非线性响应的影响。此外，我们将总信号分解为距离界面不同距离的层的贡献，从而使我们能够将表面特定贡献与漫射层的贡献区分开来。结构（密度，偶极取向）和静电（电荷密度，电场，电势）特性的轴向分布分析使我们能够将它们与光学响应联系起来。该方法也可应用于其他溶剂，研究不同类型的溶解离子和分子对非共振SH信号的影响。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Molecular Liquids 化学-物理：原子、分子和化学物理

CiteScore

10.30

自引率

16.70%

发文量

2597

审稿时长

78 days

期刊介绍： The journal includes papers in the following areas: – Simple organic liquids and mixtures – Ionic liquids – Surfactant solutions (including micelles and vesicles) and liquid interfaces – Colloidal solutions and nanoparticles – Thermotropic and lyotropic liquid crystals – Ferrofluids – Water, aqueous solutions and other hydrogen-bonded liquids – Lubricants, polymer solutions and melts – Molten metals and salts – Phase transitions and critical phenomena in liquids and confined fluids – Self assembly in complex liquids.– Biomolecules in solution The emphasis is on the molecular (or microscopic) understanding of particular liquids or liquid systems, especially concerning structure, dynamics and intermolecular forces. The experimental techniques used may include: – Conventional spectroscopy (mid-IR and far-IR, Raman, NMR, etc.) – Non-linear optics and time resolved spectroscopy (psec, fsec, asec, ISRS, etc.) – Light scattering (Rayleigh, Brillouin, PCS, etc.) – Dielectric relaxation – X-ray and neutron scattering and diffraction. Experimental studies, computer simulations (MD or MC) and analytical theory will be considered for publication; papers just reporting experimental results that do not contribute to the understanding of the fundamentals of molecular and ionic liquids will not be accepted. Only papers of a non-routine nature and advancing the field will be considered for publication.