Electronic structure of warm dense matter

The electronic structure of warm dense matter has been investigated using absorption spectroscopy by looking at shifts in the K-edge position of shocked compressed parylene-C and potassium chloride. The Vulcan laser facility was used to drive double sided shocks into the embedded chlorine samples creating a warm dense matter state with compressions greater than four times solid density and temperatures of around 10 eV. This resulted in red-shifts of the K-edge energy on the order of 10 eV. Also measured are differences in the edge energy with increasing density between the two types of chlorine samples, demonstrating how the embedded environment can effect the electronic structure of the plasma under warm dense conditions. The experimental results have been reproduced well by a reformulated version of the Stewart-Pyatt model that takes into consideration dynamical processes by including an additional relaxation energy exchange between the atom and its surrounding plasma when an electron is photo-ionised from the K-shell. In addition to this good agreement with the experimental results is also observed with simulations carried out using density functional theory.