Duboisset Julien, Rondepierre Fabien, Brevet Pierre-François
Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, F-13013 Marseille, France.
Institut Lumière Matière, Université de Lyon, UMR 5306 CNRS and Université Claude Bernard Lyon1, F-69622 Villeurbanne, France.
J Phys Chem Lett. 2020 Nov 19;11(22):9869-9875. doi: 10.1021/acs.jpclett.0c02705. Epub 2020 Nov 10.
Long-range orientational correlations in liquids have received recent renewed interest, in particular for the neat water case. These long-range orientational correlations, exceeding several tens of nanometers, originate from the presence of the strong permanent water dipolar moment. However, the exact dependence with the dipolar moment and the role of other local forces like steric hindrance has never been addressed. In this work, we experimentally measure long-range correlations for a set of liquids differing by their molecular weight and dipolar moment, in order to reveal the origin of their long-range organization. Hence, we show that the dipolar moment of a solvent molecule is not the unique feature determining the orientational correlation. Steric hindrance significantly helps to structure the liquids as well. In order to quantify these long-range correlations, we also derive theoretically the polarization resolved second harmonic scattering intensity as a function of the rotational invariants describing the dipolar and octupolar interaction.
液体中的长程取向相关性最近重新引起了人们的兴趣，特别是对于纯水溶液的情况。这些超过几十纳米的长程取向相关性源于强永久水偶极矩的存在。然而，与偶极矩的确切关系以及其他局部力（如空间位阻）的作用从未得到探讨。在这项工作中，我们通过实验测量了一组分子量和偶极矩不同的液体的长程相关性，以揭示它们长程有序排列的起源。因此，我们表明溶剂分子的偶极矩不是决定取向相关性的唯一因素。空间位阻也显著有助于液体形成结构。为了量化这些长程相关性，我们还从理论上推导了偏振分辨二次谐波散射强度作为描述偶极和八极相互作用的旋转不变量的函数。
