X-ray Heating and Ultrafast Melting

Many approaches to studying high energy density states of matter heat samples directly, whether by optical laser irradiation or charged particle beams. With the development of X-ray Free Electron Lasers, with far higher brilliances than were previously available, sample heating by X-ray irradiation has become possible. This allows ultrafast, volumetric heating, opening up very different states of matter, with uniquely large differences in the electron and ion temperatures. This seminar will present results from the SACLA X-ray Free Electron Laser, in Hyōgo, Japan. A variety of samples were irradiated with a high intensity (~10^19 W/cm2) X-ray pulse, and changes in the diffraction pattern observed. In non-metallic samples, we see disordering within 10s of femtoseconds, while metallic samples appear to respond only thermally, on significantly longer timescales.