Abstract X-ray Absorption Spectroscopy (XAS) is known to be an ideal technique for investigating matter lacking crystalline ordering. This work reports about present methods used for investigating disordered matter, discussing data-analysis and simulations strategies as well as several experimental techniques with applications. The current approach based on the comparison among multiple-scattering simulations associated with the n-body distribution functions and EXAFS (Extended X-ray Absorption Fine Structure) experimental data, including application of Reverse Monte Carlo methods, is discussed. Several studies of amorphous and liquid systems are presented, showing the potential of XAS in answering some important questions related to preferred local symmetries in liquid systems and presence of polymorphism in glasses and liquids. Experiments are presented discussing also the advances related to the performance of high-pressure and high-temperature experiments in disordered systems, highlighting the importance of combining XAS, x-ray diffraction and suitable diagnostics. XAS ability in measuring phase transitions and structure in undercooled metastable liquids is discussed. New possibilities offered by EXAFS measurements of light elements using inelastic scattering (x-ray Raman) are presented discussing the notable example of liquid water. Mention to new time-resolved applications at synchrotrons and free-electron lasers is also given.

中文翻译：

---

无序物质的 X 射线吸收光谱研究

摘要 X 射线吸收光谱 (XAS) 是研究缺乏晶体有序性的物质的理想技术。这项工作报告了目前用于研究无序物质的方法、讨论数据分析和模拟策略以及几种具有应用的实验技术。讨论了基于与 n 体分布函数相关的多重散射模拟和 EXAFS（扩展 X 射线吸收精细结构）实验数据（包括反向蒙特卡罗方法的应用）之间的比较的当前方法。介绍了一些关于无定形和液体系统的研究，显示了 XAS 在回答一些与液体系统中优选的局部对称性和玻璃和液体中多态性存在相关的重要问题方面的潜力。实验还讨论了与无序系统中高压和高温实验性能相关的进展，强调了结合 XAS、X 射线衍射和适当诊断的重要性。讨论了 XAS 测量过冷亚稳态液体相变和结构的能力。EXAFS 使用非弹性散射（X 射线拉曼）测量轻元素提供了新的可能性，讨论了液态水的显着例子。还提到了同步加速器和自由电子激光器的新时间分辨应用。讨论了 XAS 测量过冷亚稳态液体相变和结构的能力。EXAFS 使用非弹性散射（X 射线拉曼）测量轻元素提供了新的可能性，讨论了液态水的显着例子。还提到了同步加速器和自由电子激光器的新时间分辨应用。讨论了 XAS 测量过冷亚稳态液体相变和结构的能力。EXAFS 使用非弹性散射（X 射线拉曼）测量轻元素提供了新的可能性，讨论了液态水的显着例子。还提到了同步加速器和自由电子激光器的新时间分辨应用。