X-ray photoabsorption of warm dense matter

Summary form only given, as follows. Time-resolved X-ray photoabsorption enables one to probe the electronic structure of materials at high temperature and near-solid densities. X-rays from the Advanced Light Source synchrotron are focused onto a thin foil sample, dispersed by a flat-field spectrometer and detected by a streak camera. The sample is heated isochorically by a femtosecond laser pulse. A short time after the laser pulse, about 10 ps, a thin aluminum sample is at uniform temperature, about 1 eV, and density according to hydrodynamic simulations. Near-edge photoabsorption spectra at the aluminum L edge have been obtained using 5 X-ray pulses. Silicon samples are also being studied.