发表机构
Stockholm University; Saint Petersburg State University; Deutsches Elektronen-Synchrotron DESY; Technische Universität Bergakademie Freiberg; ESRF – The European Synchrotron（斯德哥尔摩大学; 圣彼得堡国立大学; 德国电子同步加速器中心; 弗莱贝格矿业科技大学; 欧洲同步辐射装置）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究过冷水-甘油溶液的结构演化，采用XPCS、USAXS与WAXS结合的方法，发现液-液相分离先于冰结晶发生，相场模拟验证旋节线分解场景，为区分两过程提供了途径。
AI 中文摘要
理解过冷水-甘油溶液的结构演化对低温保存具有重要意义，但区分液态转变与冰结晶仍极具挑战性。本研究采用X射线光子关联谱（XPCS）结合超小角X射线散射（USAXS）几何构型，以及广角X射线散射（WAXS），对深过冷水-甘油溶液开展研究。该组合技术可同时捕捉过冷液体在淬冷至低温（172 K）时的结构与动力学演化。我们观测到分子尺度上液体结构的不连续变化及微尺度畴的形成，此阶段动力学减慢，呈现超扩散、类弹道弛豫特征。该转变先于冰结晶发生，我们通过WAXS中冰布拉格峰的出现识别冰结晶，实现两个过程的时间分离。相场（Cahn-Hilliard）模拟定性复现了实验观测，表明旋节线分解场景与测得的散射演化一致。这些发现与“液-液相分离先于冰结晶”的场景相符，为解开过冷水体系中两个过程的关联提供了途径。
英文摘要
Understanding the structural evolution of supercooled water-glycerol solutions is important for cryopreservation, yet distinguishing liquid-state transformations from ice crystallization remains challenging. Here, we investigate a deeply supercooled water-glycerol solution by X-ray photon correlation spectroscopy (XPCS) in ultra-small-angle X-ray scattering (USAXS) geometry, combined with wide-angle X-ray scattering (WAXS). This combination simultaneously captures the structural and dynamical evolution of the supercooled liquid upon quenching to cryogenic temperatures (172 K). We observe discontinuous changes in the liquid structure on molecular length scales and formation of microscale domains. The dynamics slow down during this stage and exhibit hyper-diffusive, ballistic-like relaxation. This transformation precedes ice crystallization, which we identify from the emergence of ice Bragg peaks in WAXS, allowing the two processes to be temporally separated. Phase-field (Cahn-Hilliard) simulations qualitatively reproduce the experimental observations and show that a spinodal-decomposition scenario is consistent with the measured scattering evolution. These findings are consistent with a liquid-liquid phase separation scenario preceding ice crystallization and provide a route to disentangle the two processes in supercooled aqueous systems.
CommentsSubmitted to The Journal of Chemical Physics
