Insight into the spatial ordering and dynamics of structural heterogeneity in materials is at the heart of understanding their structure and function. X-ray photon correlation spectroscopy (XPCS) measures the dynamic structure factor $S(Q,t)$ providing information on the spontaneous low-energy dynamics intrinsic to many materials. Combined with in situ and in operando capabilities, XPCS provides unique insight into a variety of scientific areas, including phase separation in binary alloys, aging in metallic glasses, surface dynamics during growth, domain wall dynamics in ferroic complex oxides and charge and spin density wave motion in quantum materials. This review summarizes some recent XPCS work in these areas and discusses scientific opportunities that will be made possible with the many-fold increase in coherent flux provided by the world-wide construction and commissioning of X-ray sources based on multi-bend achromat (MBA) storage ring (SR) lattices and high repetition rate free electron lasers (FELs).

了解材料中结构异质性的空间有序性和动力学是了解它们的结构和功能的核心。X射线光子相关光谱法（XPCS）测量动态结构因子$\mathrm{小号}（问，Ť）$提供有关许多材料固有的自发性低能量动力学的信息。结合就地和操作功能，XPCS提供了对各种科学领域的独特见解，包括二元合金的相分离，金属玻璃的时效，生长过程中的表面动力学，铁性复合氧化物的畴壁动力学以及电荷和自旋密度波量子材料中的运动。这篇综述总结了XPCS在这些领域中的最新工作，并讨论了由于基于多弯曲消色差（MBA）的全球X射线源的建造和调试所提供的相干通量的倍增，科学机遇将得以实现。 ）储存环（SR）晶格和高重复频率的自由电子激光器（FEL）。