We studied the behavior of the reflectivity along the principal Hugoniot of deuterium for shock velocities from 20 to 60 km/s in the warm dense matter regime using molecular dynamics simulations within a Kohn-Sham density-functional formulation. We find that in the wavelength range between 400 and 1000 nm the reflectivity shows a change in form as a function of shock velocity (pressure) around 45 km/s as the medium transforms from a poor to a good conductor, corresponding to concomitant change in the frequency-dependent electrical conductivity. Therefore, the behavior of the reflectivity can serve as an effective experimental probe into the basic nature of an environment under extreme conditions.

• Received 17 January 2012

DOI:https://doi.org/10.1103/PhysRevB.85.233101