Application of ultrafast x-ray lasers in studying the material structure under shock compression

For more than a century, x rays have been an essential tool in physics, chemistry, biology, materials science, and other subjects, considerably expanding our understanding of the fundamental structure of materials. X rays and electrons are among the most useful tools in the scientific toolbox for understanding the properties and functions of materials and molecules because of their capacity to penetrate matter and differentiate the structural changes at the atomic level. This information has a wide range of applications, including the development of innovative materials for electronics and clean energy technologies, as well as more effective pharmaceuticals with fewer side effects. A major new field in x-ray science has been opened by recent developments in ultrafast x-ray sources operating in the femtosecond (fs) to atto-second regimes. These advancements make possible element-specific probing of dynamics of charge particles and electronic configurations of electronic motions at fundamental timescales, sensitive probing of structural dynamics in materials at the atomic and electronic level at fundamental timescales, and efficient new methods for examining the coupling between atomic and electronic structural dynamics to investigate the material properties and functions. The most significant advancement has been the latest discovery of x-ray free-electron lasers (XFELs), of which there are now many new facilities either operational or under development worldwide. In addition, the development of high-order harmonic extreme ultraviolet sources based on lasers that operate in the atto-second regime as well as the tabletop and synchrotron-based laser-plasma x-ray sources that operate in the fs regime complement the achievements of XFEL. The current article provides a comprehensive discussion and future perspectives on the application of ultrafast XFELs to study the structure of matter under shock compression.