Single-Shot Multi-Kev X-Ray Absorption Spectroscopy Using an Ultrashort Laser Wakefield Accelerator Source

X-ray absorption spectroscopy (XAS) can provide a wealth of information regarding the structure and state of a sample. Techniques such as XANES (X-ray Absorption Near Edge Structure) and EXAFS (Extended X-ray Absorption Fine Structure) provide a simultaneous measurement of the temperature and structure of both the electronic and ionic distributions. Making these measurements using a single ultrashort probe pulse provides a powerful tool for investigating, for example, laboratory-based high energy-density samples. These states are notoriously difficult to probe due to their extreme conditions, transient nature, and often limited shot rate. We present high-resolution single-shot K-edge XAS measurements of cold titanium and copper samples from recent experiments using a laser wakefield accelerator source at the Gemini laser facility 1 . Up to 1.2± 0.2x10 6 photons/eV per shot where generated with a smooth broadband spectrum, and a few femtosecond pulse duration. We demonstrate that this source is capable of single-shot simultaneous measurements of both the electron and ion distributions in matter heated to eV temperatures by comparison with density functional theory simulations. The unique combination of a high-flux, large bandwidth, few femtosecond duration x-ray pulse synchronized to a high-power laser will enable key advances in the study of ultrafast energetic processes such as electron-ion equilibration and non-thermal phase transitions.