Using x-ray-free-electron lasers to generate and probe high-energy-density matter

The world's first hard x-ray free electron laser, the Linac Coherent Light Source (LCLS) has become available, providing 10 to 500 fs x-ray pulses in the 2.5 and 0.15 nm wavelength range and 4 mJ pulse energies. Utilizing this laser, we studied ultrafast processes in warm dense matter, including ionization, energy transfer, and atomic motion. We used the unique high peak-brightness radiation to heat carbon solids isochorically to up to 50 electron volts. We then used the LCLS pulses to probe the state of the material via by Bragg and x-ray Thomson scattering. Elastic Bragg scattering provides ionic properties and structural information about the crystal, while the inelastic Compton and plasmon scattering spectrum reflects the electrical/optical properties, and further provides temperature and density information. In this presentation, we will report on the first experimental results and compare them to model calculations