Studying the long-wavelength dynamics in glass-forming liquids

We propose to study the long-wavelength dynamics in glass-forming liquids using small-angle XPCS at ID10. The dynamics in glass-forming liquids shows a rich behavior depending on the length scale being considered. In particular, the intermediate Q-range between the hydrodynamic limit (Q -> 0) and the structure factor maximum (corresponding to interatomic distances) is largely unexplored and in need of experimental data for a better understanding. The successful operation of EBS should greatly facilitate XPCS measurements in this Q-range where scattering is weak. We propose to measure and compare several different metallic glass formers with various compositions, in order to disentangle the effects of concentration and density fluctuations on the dynamics of glass-forming liquids.

我们提出依托ID10束线的小角X射线光子关联光谱（small-angle XPCS），开展玻璃形成液体的长波长动力学研究。玻璃形成液体的动力学行为随所考察的长度尺度展现出丰富的演化特征。尤为值得关注的是，介于流体力学极限（Q→0）与结构因子峰（对应原子间间距）之间的中间散射矢量Q区间，目前仍鲜有系统性探索，亟需补充实验数据以实现更深入的认知。增强型高亮度同步辐射光源（EBS）的顺利投用，将极大推动该散射强度较弱的波矢区间内的XPCS测量工作。我们拟对多种不同成分的金属玻璃形成合金开展测量并进行对比分析，以期厘清浓度涨落与密度涨落对玻璃形成液体动力学行为的影响机制。